Patent Publication Number: US-11642223-B2

Title: Shoulder prosthesis components and assemblies

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATIONS 
     Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 C.F.R. § 1.57. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present application relates to apparatuses and methods for reverse and/or anatomic shoulder prostheses. 
     Description of the Related Art 
     Arthroplasty is the standard of care for the treatment of shoulder joint arthritis. A typical anatomical shoulder joint replacement attempts to mimic anatomic conditions. A metallic humeral stem and a humeral head replacement are attached to the humerus of the arm and replace the humeral side of the arthritic shoulder joint. Such humeral head replacement can articulate with the native glenoid socket or with an opposing glenoid resurfacing device. 
     For more severe cases, a reverse reconstruction can be employed. In a reverse reconstruction the kinematics of the shoulder joint are reversed by securing a spherical device (sometimes called a glenoid sphere) to the glenoid and implanting a humeral implant with a cavity capable of receiving the glenoid sphere. 
     In some treatments, the clinician may use a kit that includes many different components and tools for implanting anatomical and reverse anatomical shoulder reconstructions. The use of numerous tools can increase the cost of the treatment procedure, and may unnecessarily complicate the procedure. Accordingly, there remains a continuing need for improved shoulder prosthesis components and assemblies. 
     SUMMARY OF THE INVENTION 
     Improved humeral components, kits, assemblies, and methods are needed to provide more robust implantation of the anchor (whether a stemless anchor or a stemmed anchor) into the humerus. Various embodiments disclosed herein relate to improved stemless humeral anchors having elongate distal fins and that serve a bone filling function. Moreover, it can be desirable to utilize a kit that reduces the number of humeral anchors and/or tools used to implant the anchors. Various embodiments disclosed herein relate to kits and systems that provide a shared tooling interface for stemless and stemmed humeral anchors, such that the clinician can use a shared set of tools for implanting stemless and stemmed anchors, and for performing both anatomical and reverse anatomical reconstructions. 
     In one embodiment, a humeral anchor is disclosed. The humeral anchor can include a distal portion extending proximally from a distal end of the humeral anchor, the distal portion configured to occupy a portion of a metaphysis of a humerus when implanted. The humeral anchor can include a proximal portion extending distally from a proximal end of the humeral anchor. The humeral anchor can include a recess extending distally from the proximal end of the humeral anchor and into the proximal portion. The humeral anchor can include an inner periphery disposed about the recess adjacent to the proximal end of the humeral anchor. The inner periphery can include a concave locking feature disposed in the inner periphery. The inner periphery can include a convex locking feature disposed in the inner periphery, the concave locking feature spaced apart from the convex locking feature. 
     In some embodiments, the concave locking feature can include a first concave locking feature and a second concave locking feature disposed opposite the first concave locking feature. The first concave locking feature and the second concave locking features can be disposed at medial and lateral portions of the humeral anchor respectively. The convex locking feature can include a first convex locking feature and a second convex locking feature disposed opposite the first convex locking feature. The first convex locking feature and the second convex locking features can be disposed at anterior and posterior portions of the humeral anchor respectively. The concave locking feature can be configured to provide an interference fit for an articular body comprising a concave articular surface. The convex locking feature can include an elongate fin projecting toward the recess. The humeral anchor can include a stemless humeral anchor. The distal portion can include a first section and a second section distal the first section, the second section comprising a fin extending distally from the first section. The second section can include a plurality of fins extending distally from the first section. The first section can include a second recess distal the recess. A stem can extend from the distal end of the humeral anchor. 
     In another embodiment, a humeral anchor is disclosed. The humeral anchor can include a distal portion extending proximally from a distal end of the humeral anchor, the distal portion configured to occupy a portion of a metaphysis of a humerus when implanted. The humeral anchor can include a proximal portion extending distally from a proximal end of the humeral anchor and having an outer surface that is enlarged to occupy at least a majority of the volume of a metaphysis of a humerus into which the humeral anchor is to be disposed. The proximal portion can have a lateral side configured to be disposed adjacent to a cortical wall of a lateral portion of a humeral metaphysis and a medial side configured to be spaced apart from a cortical wall of a medial side of the humeral metaphysis. The humeral anchor can include a bone compression surface disposed at the proximal end of the humeral anchor, the bone compression surface being disposed about the medial side of the proximal portion and being configured to extend from the medial side of the proximal portion to the cortical wall of the medial side of the humeral metaphysis when implanted in a humerus. 
     In some embodiments, the bone compression surface can include a flange that extends outward from the proximal end of the proximal portion of the humeral anchor. The flange can include a circular outer periphery having a radius corresponding to a radius of the lateral side of the proximal portion. An annular surface can be disposed at a proximal face of the humeral anchor, the flange comprising a portion of the annular surface of a proximal face. Rotational orientation indicia can be formed on or in the annular surface disposed at the proximal face of the humeral anchor. A recess can extend distally from the proximal end of the humeral anchor and into the proximal portion and an inner periphery disposed about the recess adjacent to the proximal end of the humeral anchor, the inner periphery comprising a locking feature disposed in the inner periphery, the locking features being aligned with the bone compression surface. 
     In another embodiment, a kit for a shoulder prosthesis is disclosed. The kit can include a first stemless humeral anchor comprising a first distal portion configured to occupy a portion of a metaphysis of a humerus when implanted. The first stemless humeral anchor can comprise a first proximal portion extending proximally from a proximal end of the first distal portion to a proximal end of the first humeral anchor. The first stemless humeral anchor can comprise a first recess extending from the proximal end of the first humeral anchor into the first proximal portion. The first stemless humeral anchor can comprise a first distally-extending fin, the first fin extending distally from the first distal portion to a distal end of the first humeral anchor, a first height defined between the proximal and distal ends of the first humeral anchor. The kit can include a second stemless humeral anchor comprising a second distal portion configured to occupy a portion of a metaphysis of a humerus when implanted. The second stemless humeral anchor can comprise a second proximal portion extending proximally from a proximal end of the second distal portion to a proximal end of the second humeral anchor. The second stemless humeral anchor can include a second recess extending from the proximal end of the second humeral anchor into the second proximal portion. The second stemless humeral anchor can include a second distally-extending fin, the second fin extending distally from the second distal portion to a distal end of the second humeral anchor, a second height defined between the proximal and distal ends of the second humeral anchor. A ratio of the second height to the first height can be in a range of 1.15 to 2.5. 
     In some embodiments, the kit can include a first stemmed humeral anchor having an anchor body and a stem extending distally from the anchor body. The kit can include one or more articular components configured to connect to the first and second humeral anchors. The one or more articular components can comprise an anatomic articular component having a rounded, convex surface configured to engage a glenoid surface of the patient. The one or more articular components can include a reverse articular body having a rounded, concave surface. 
     In another embodiment, a humeral anchor is disclosed. The humeral anchor can comprise an interior surface disposed about a first recess between a first end of the humeral anchor and a second location, and disposed about a second recess between the second location and a third location, the first and second recesses having different volumes. The humeral anchor can comprise a distally-extending fin, the fin extending distally from the third location to a second end of the humeral anchor, the fin having a fin height that is at least 10% of a total height of the humeral anchor. 
     In some embodiments, the humeral anchor can include a plurality of distally-extending fins extending distally from the third location to the second end. The plurality of fins can include a first fin extending along an inferior direction of the anchor and a second fin having directional components extending along a superior direction and one of an anterior and posterior direction. The humeral anchor can include an inner periphery disposed about the first recess adjacent to the first end of the humeral anchor. The inner periphery can include a concave locking feature disposed in the inner periphery. The inner periphery can include a convex locking feature disposed in the inner periphery, the concave locking feature spaced apart from the convex locking feature. 
     In another embodiment, a method of implanting a shoulder prosthesis into a patient is disclosed. The shoulder prosthesis can comprise a stemless humeral anchor having an anchor body and a plurality of fins extending distally from the anchor body. The method can include removing a portion of a humerus of the patient to form a cavity in the humerus. The method can include orienting the stemless humeral anchor relative to the humerus such that a first fin of the plurality of fins is oriented along an inferior direction and a second fin of the plurality of fins is oriented to have directional components along a superior direction and one of an anterior and posterior direction. The method can include inserting the stemless humeral anchor into the cavity of the humerus. 
     In some embodiments, the method can include orienting the stemless humeral anchor relative to the humerus such that the second fin is oriented to have directional components along the superior direction and the anterior direction. The method can further comprise orienting the stemless humeral anchor relative to the humerus such that a third fin of the plurality of fins is oriented to have directional components along the superior direction and the posterior direction. The first and second fins can be angled relative to one another by a first angle, wherein the second and third fins are angled relative to one another by a second angle equal to the first angle. The method can include resecting the humerus to form a resection surface prior to removing the portion of the humerus. Removing the portion of the humerus can comprise reaming the humerus to form the cavity. The method can include drilling a second cavity distal to and having a smaller diameter relative to the cavity. The method can include connecting an articular body to the stemless humeral anchor. 
     In another embodiment, a humeral anchor is disclosed. The humeral anchor can include a distal portion extending proximally from a distal end of the humeral anchor, the distal portion extending along a longitudinal axis of the humeral anchor, the distal portion being tapered inwardly along the longitudinal axis toward the distal end of the humeral anchor. The humeral anchor can include a proximal portion extending distally from a proximal end of the humeral anchor. The humeral anchor can include a recess extending distally from the proximal end of the humeral anchor and into the proximal portion. The humeral anchor can include an inner periphery disposed about the recess adjacent to the proximal end of the humeral anchor. The inner periphery can comprise a concave locking feature disposed in the inner periphery. The inner periphery can comprise a convex locking feature disposed in the inner periphery, the concave locking feature spaced apart from the convex locking feature. 
     In some embodiments, the concave locking feature can include a first concave locking feature and a second concave locking feature disposed opposite the first concave locking feature. The first concave locking feature and the second concave locking features can be disposed at medial and lateral portions of the humeral anchor respectively. The convex locking feature can include a first convex locking feature and a second convex locking feature disposed opposite the first convex locking feature. The first convex locking feature and the second convex locking features can be disposed at anterior and posterior portions of the humeral anchor respectively. The concave locking feature can be configured to provide an interference fit for an articular body comprising a concave articular surface. The convex locking feature can comprise an elongate fin projecting toward the recess. 
     In another embodiment, a humeral anchor is disclosed. The humeral anchor can include a distal portion extending proximally from a distal end of the humeral anchor, the distal portion extending along a longitudinal axis of the humeral anchor. The humeral anchor can include a proximal portion extending distally from a proximal end of the humeral anchor and having an outer surface that is enlarged to occupy at least a majority of the volume of a metaphysis of a humerus into which the humeral anchor is to be disposed. The proximal portion can have a lateral side configured to be disposed adjacent to a cortical wall of a lateral portion of a humeral metaphysis us and a medial side configured to be spaced apart from a cortical wall of a medial side of the humeral metaphysis. The humeral anchor can include a bone compression surface disposed adjacent to the proximal end of the humeral anchor, the bone compression surface being disposed about only the medial side of the proximal portion and being configured to extend from the medial side of the proximal portion to the cortical wall of the medial side of the humeral metaphysis when implanted in a humerus. 
     In some embodiments, the bone compression surface can comprise a flange that extends outward from the proximal end of the proximal portion of the humeral anchor. The flange can comprise a circular outer periphery having a radius corresponding to a radius of the lateral side of the proximal portion. An annular surface can be disposed at a proximal face of the humeral anchor, the flange comprising a portion of the annular surface of a proximal face. Rotational orientation indicia can be formed on or in the annular surface disposed at the proximal face of the humeral anchor. A recess can extend distally from the proximal end of the humeral anchor and into the proximal portion and an inner periphery disposed about the recess adjacent to the proximal end of the humeral anchor, the inner periphery comprising a locking feature disposed in the inner periphery, the locking features being aligned with the bone compression surface. 
     In another embodiment, a humeral anchor is disclosed. The humeral anchor can include a proximal portion having an enlarged outer surface extending distally from a proximal end of the humeral anchor. The humeral anchor can include a distal portion extending between the proximal portion and a distal end of the humeral anchor, the distal portion extending along a longitudinal axis of the humeral anchor. The distal portion can include a circular periphery at a first location along the longitudinal axis of the humeral anchor adjacent to the distal end. The distal portion can include an oblong periphery at a second location disposed between the first location and the proximal end of the humeral anchor. The distal portion can comprise an at least partially polygonal periphery at a third location disposed between the second location and the proximal end of the humeral anchor. The distal portion can comprise an anti-rotation fin disposed at an edge of the at least partially polygonal periphery. 
     In some embodiments, one or more circular peripheries are disposed along a length of the humeral anchor from the distal end to the first location. The oblong periphery can comprise a first dimension in an anterior-posterior direction and a second dimension in a medial lateral direction, the second dimension being larger than the first dimension. The at least partially polygonal periphery can comprise a curved convex side configured to be oriented laterally and a generally anterior-posterior oriented side disposed between ends of the convex side. The anti-rotation fin can comprise a projection extending in a medial direction from the generally anterior-posterior oriented side. The at least partially polygonal periphery can be in a cross-section oriented at an angle to a longitudinal axis of the distal portion and parallel to the proximal end of the humeral anchor. The humeral anchor can include a second at least partially polygonal periphery disposed at a fourth location between the third location and the proximal end of the humeral anchor, an anti-rotation fin being disposed at the second at least partially polygonal periphery. The anti-rotation fin can extend continuously from the at least partially polygonal periphery at the third location to the second at least partially polygonal periphery at the fourth location. 
     In another embodiment, a bone anchor inserter is disclosed. The bone anchor inserter can include a first end and a second end opposite the first end. The bone anchor inserter can include an elongate body extending along a longitudinal axis between the first end and the second end. The bone anchor inserter can include a handle disposed between the first end and the second end, the handle having a first configuration and a second configuration. The bone anchor inserter can include a bone anchor interface disposed at the second end, the bone anchor interface having a bone anchor retention configuration corresponding to the first configuration of the handle and a bone anchor release configuration corresponding to the second configuration of the handle. The bone anchor inserter can include a first impaction head coupled with the elongate body and disposed at a first angle to the longitudinal axis thereof. The bone anchor inserter can include a second impaction head coupled with the elongate body and disposed at a second angle to the longitudinal axis thereof. A force applied to the first impaction head can direct an impacting force to a first bone anchor in a direction aligned with a longitudinal axis of the first bone anchor to embed the first bone anchor in the bone. A force applied to the second impaction head can direct an impacting force to a second bone anchor, the impacting force applied to the second impaction head oriented in a direction perpendicular to a resection plane of the bone to embed the second bone anchor in the bone. 
     In some embodiments, the first impaction head can be disposed at an angle to the second impaction head. An angle between 35 degrees and 65 degrees can be disposed between the first impaction head and the second impaction head. The handle can be pivotably coupled with the elongate body, the first configuration and the second configuration provided by pivoting the handle. A spring can be disposed between the handle and the elongate body to facilitate placement and retention of the bone anchor interface in the bone anchor retention configuration. 
     In another embodiments, a bone anchor inserter is disclosed. The bone anchor inserter can include a first end and a second end opposite the first end. The bone anchor inserter can include an elongate body extending between the first end and the second end along a longitudinal axis. The bone anchor inserter can include a bone anchor interface disposed at the second end, the bone anchor interface having a bone anchor retention configuration and a bone anchor release configuration. The bone anchor inserter can include an impaction head coupled with the elongate body and disposed at an end of the elongate body adjacent to the second end and opposite the first end. A force applied to the impaction head can direct an impacting force to a stem portion of a bone anchor, the impacting force applied to the impaction head oriented in a direction aligned with a longitudinal axis of the bone anchor to embed the stem portion of the bone anchor within the medullary canal. 
     In some embodiments, the impaction head can be oriented at an acute angle to the longitudinal axis of the elongate body. 
     In another embodiment, a kit is disclosed. The kit can include a stemless bone anchor comprising a first portion configured to be advanced into a metaphysis portion such that the first portion is disposed between a resection surface and a continuous expanse of bone disposed between the resection surface and a medullary canal of the bone. The stemless bone anchor can comprise a second portion opposite the first portion, the second portion comprising an inserter interface. The bone anchor inserter can include a bone anchor comprising a first portion and a second portion opposite the first portion, the first portion comprising a stem configured to be advanced into a diaphysis portion and into a medullary canal of the bone and a second portion, the second portion comprising an inserter interface. The bone anchor inserter can include an inserter comprising a bone anchor interface, the bone anchor interface configured to be engaged with the inserter interface of the stemless bone anchor or with the inserter interface of the bone anchor comprising the stem. 
     In some embodiments, the inserter can further comprise an impaction head disposed between the bone anchor interface and an end of the inserter opposite to the bone anchor interface, the impaction head configured to transfer an impacting force applied to the impaction head to bone anchor comprising the stem to embed the stem in a medullary canal of a bone. The impaction head can be a first impaction head and further comprising a second impaction head disposed at an angle to the second impaction head. The angle between the first impaction head and the second impaction head can be 45 degrees. The angle between the first impaction head and the second impaction head can be between 35 degrees and 65 degrees. The inserter can comprise a first impaction head and a second impaction head disposed at a first angle to each other. A second inserter can comprise a bone anchor interface, the bone anchor interface configured to be engaged with the inserter interface of the stemless bone anchor or with the inserter interface of the bone anchor comprising the stem, the second inserter comprising a first impaction head and a second impaction head disposed at a second angle relative to each other. Each of the first angle and the second angle can be between 35 degrees and 65 degrees. 
     In another embodiment, a method is disclosed. The method can include providing a first bone anchor comprising a stemless bone engagement portion, a second bone anchor comprising a stem, the first bone anchor and the second bone anchor each comprising an inserter interface, and an inserter comprising a bone anchor interface configured to engage the inserter interface of either the first bone anchor or the second bone anchor. The method can include engaging the bone anchor interface of the inserter with the inserter interface of the first bone anchor. The method can include advancing the first bone anchor into bone matter exposed at a resection of a bone. The method can include engaging the bone anchor interface of the inserter with the inserter interface of the second bone anchor. The method can include advancing the second bone anchor into bone matter at the resection of the bone to position the stem of the second bone anchor in a medullary canal of the bone. 
     In some embodiments, advancing the second bone anchor into bone matter can further comprise applying a force to an impaction head of the inserter to apply a force aligned with the second bone anchor to embed the stem in the bone. The impaction head can be a first impaction head and advancing the first bone anchor into bone matter can further comprise applying a force to a second impaction head of the inserter to apply a force perpendicular to the resection of the bone. Advancing the first bone anchor into bone matter can further comprise applying a force to an impaction head of the inserter to apply a force perpendicular to the resection of the bone. The inserter can be a first inserter. The method can comprise providing a second inserter. The first inserter and the second inserter can each have a stemmed anchor impaction head and a stemless anchor impaction head. The first inserter can have a first angle between the stemmed anchor impaction head and the stemless anchor impaction head thereof. The second inserter can have a second angle between the stemmed anchor impaction head and the stemless anchor impaction head thereof. The second angle can be different from the first angle. The method can comprise selecting one of the first inserter or the second inserter based on an angle at which a resection is formed in the bone. The first angle and the second angle can be between 35 degrees to 65 degrees. 
     In another embodiment, a device for removing bone is disclosed. The device can include a proximal end and a distal end. The device can include a drive shaft at the proximal end of the device, the drive shaft rotatable about a drive shaft axis. The device can include a reamer head rotatable about the drive shaft axis to remove bone. The reamer head can include a distal portion comprising a plurality of radial arms, each of the plurality of radial arms comprising a lateral cutting edge. The reamer head can include a proximal portion comprising a distal facing cutting edge. 
     In some embodiments, each of the plurality of radial arms can comprise a first flat face and a second flat face opposite the first flat face, the first and second flat faces separated by a thickness. A width of each of the first and second flat faces, measured in a radial direction, can be greater than the thickness. Each of the plurality of arms can comprise a proximal section and a distal section, the proximal section projecting radially outward of the distal section. A guide channel can be configured to receive a guide pin, each of the plurality of radial arms extending radially outward from the guide channel. The proximal portion can comprise a depth stop configured to control an insertion depth of the reamer head, the depth stop being proximal of and extending radially outward of the distal facing cutting edge. The distal facing cutting edge can be positioned radially outward of the plurality of radial arms. The distal facing cutting edge can extend circumferentially around the proximal portion of the reamer head. The distal facing cutting edge can comprise a plurality of cutting teeth. The proximal portion of the reamer head can comprise a plurality of apertures in a proximal face of the reamer head. 
     In another embodiment, a device for removing bone is disclosed. The device can include a first end and a second end. The device can include a drive shaft at the first end of the device, the drive shaft rotatable about a drive shaft axis. The device can include a reamer head rotatable about the drive shaft axis to remove bone. The reamer head can include an inner portion comprising a lateral facing cutting edge, the inner portion configured to form a first cavity portion in the bone, a second cavity portion at a greater depth than the first cavity portion, and a stepped portion between the first cavity portion and the second cavity portion. An outer portion can be positioned radially outward of the inner portion, the outer portion comprising a distal facing cutting edge, the outer portion configured to form a recessed surface proximal of and at least partially surrounding the first cavity portion. 
     In some embodiments, a profile of the distal facing cutting edge can be different from a profile of the lateral facing cutting edge. The second cutting edge can comprise a plurality of cutting teeth. A guide channel can be configured to receive a guide pin. The reamer head further can comprise a depth stop configured to control an insertion depth of the reamer head, the depth stop being proximal of and extending radially outward of the distal facing cutting edge. 
     In another embodiment, a method of removing bone is disclosed. The method can include advancing a reamer toward an end of a bone, the reamer comprising a drive shaft and a reaming head. The method can include driving the reamer about a drive axis of the drive shaft. The method can include forming a cavity in the bone with the reaming head. The cavity can comprise a first cavity portion and a second cavity portion extending a greater depth into the bone than the first cavity portion. The cavity can include a stepped portion between the first cavity portion and the second cavity portion. The method can include forming a recessed surface below a resection plane of the bone with the reaming head, the recessed surface at least partially surrounding the first cavity portion. The method can include positioning an anchor structure of an implant in the cavity in the bone. The method can include positioning a collar of the implant on the recessed surface in the bone. 
     In some embodiments, forming the cavity in the bone and forming the recessed surface can occur simultaneously. In some embodiments, forming the cavity in the bone and forming the recessed surface can occur sequentially. After forming the cavity in the bone, the recessed surface can be formed in the bone. Advancing the reamer can comprise advancing the reamer along a guide pin. The method can include forming the recessed surface in the bone until a depth stop contacts the resection plane of the bone. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects and advantages are described below with reference to the drawings, which are intended for illustrative purposes and should in no way be interpreted as limiting the scope of the embodiments. Furthermore, various features of different disclosed embodiments can be combined to form additional embodiments, which are part of this disclosure. In the drawings, like reference characters denote corresponding features consistently throughout similar embodiments. The following is a brief description of each of the drawings. 
         FIG.  1 A  shows an anatomic total shoulder arthroplasty system disposed in the humerus and the glenoid of a shoulder joint, the system including a stemless humeral anchor; 
         FIG.  1 B  shows a reverse total shoulder arthroplasty system in a shoulder joint, the system including a humeral stem anchor; 
         FIG.  2    is a schematic diagram of a shoulder arthroplasty system comprising an arthroplasty kit that can be used in performing anatomic or reverse arthroplasty, in converting from one of anatomic to reverse, or reverse to anatomic arthroplasty, according to various embodiments; 
         FIG.  3    is a side view showing an anatomical articular body connected to a humeral stemless anchor, according to various embodiments. 
         FIG.  3 A  is a side view showing a reverse articular body connected to a humeral stemless anchor, according to various embodiments. 
         FIG.  3 A- 1    is a perspective view of a stemless humeral anchor and a reverse articular assembly from the system of  FIG.  2    prior to inserting the reverse articular assembly and showing engagement features of these components. 
         FIG.  3 B  is a cross-sectional view of the stemless humeral anchor and the reverse articular assembly of  FIG.  3 A  after the reverse articular assembly has been inserted, the section being taken transverse to the direction of insertion of the reverse articular assembly. 
         FIG.  3 C  is a cross-sectional view of the stemless humeral anchor of  FIG.  3 A , the section being taken along the direction of insertion of the reverse articular assembly. 
         FIG.  4 A  is a side view of a stemless humeral anchor, according to various embodiments. 
         FIG.  4 B  is a bottom view of the stemless humeral anchor of  FIG.  4 A , according to an example. 
         FIG.  4 C  is a side view of a stemless humeral anchor, according to another embodiment. 
         FIG.  4 C- 1    is a top view of the stemless humeral anchor of  FIG.  4 C . 
         FIG.  4 C- 2    is a cross-sectional view of another embodiment of the stemless humeral anchor of  FIG.  4 C- 1    with enhanced bone retention structures, with the cross-section taken along section  4 C- 2 - 4 C- 2  in  FIG.  4 C- 1   . 
         FIG.  4 D  is a side view of a humeral anchor, according to another embodiment. 
         FIG.  4 D- 1    is a side view of a humeral anchor, according to another embodiment. 
         FIG.  4 E  is a schematic side view of a humeral anchor having a plurality of anchoring teeth, according to various embodiments, 
         FIG.  4 F  is a schematic side view of a humeral anchor having four fins, according to another embodiment. 
         FIG.  4 F- 1    is a bottom view of the stemless humeral anchor of  FIG.  4 F , according to another example. 
         FIG.  4 G  is a side view of a stemless humeral anchor having a bone-preserving profile, according to another embodiment. 
         FIG.  5    is a side sectional view of an example of a humeral stem that has a distal portion that can extend into the diaphysis of the humerus. 
         FIG.  6 A  is a side view of a humeral stem anchor, according to various embodiments. 
         FIG.  6 B  illustrates a proximal and medial aspect of the humeral stem anchor of  FIG.  6 A . 
         FIG.  6 C  illustrates a distal and lateral aspect of the humeral stem anchor of  FIG.  6 A , which includes a cancellous bone compression member. 
         FIG.  6 D  is a perspective view of a proximal portion of a humeral stem anchor, according to various embodiments. 
         FIG.  6 E  is a side sectional view of the humeral stem anchor of  FIG.  6 D , taken along section  6 E- 6 E of  FIG.  6 D . 
         FIG.  6 F  is a sectional view of the humeral stem anchor of  FIG.  6 E , taken along section  6 F- 6 F. 
         FIG.  6 G  is a sectional view of the humeral stem anchor of  FIG.  6 E , taken along section  6 G- 6 G. 
         FIG.  6 H  is a sectional view of the humeral stem anchor of  FIG.  6 E , taken along section  6 H- 6 H. 
         FIG.  6 I  is a sectional view of the humeral stem anchor of  FIG.  6 E , taken along section  6 I- 6 I. 
         FIG.  6 J  is a sectional view of the humeral stem anchor of  FIG.  6 E , taken along section  6 J- 6 J. 
         FIG.  6 K  is a sectional view of the humeral stem anchor of  FIG.  6 E , taken along section  6 K- 6 K. 
         FIG.  6 L  is a sectional view of the humeral stem anchor of  FIG.  6 E , taken along section  6 L- 6 L. 
         FIG.  6 M  is a side view of a stem humeral anchor having an extra long length, according to another embodiment. 
         FIG.  7    shows two example methods for resecting a humerus, according to various embodiments. 
         FIG.  8    illustrates a protection step in which a protection plate is provided over the resected humerus. 
         FIG.  9    illustrates a method for sizing a humerus before implanting a humeral anchor, according to various embodiments. 
         FIG.  10    illustrates an example method of reaming the resected humerus. 
         FIGS.  10 A- 10 B  illustrate examples of reamers configured to form a space suitable for a stem or stemless humeral anchor. 
         FIG.  11    illustrates an example method of blazing a reamed humerus. 
         FIGS.  11 A- 11 D  illustrate an example of an inserter configured to position a humeral anchor into the humerus. 
         FIG.  12    illustrates an example method of planing the humerus. 
         FIG.  13    illustrates an example method in which a reverse trial implant or an anatomic trial implant is inserted into the humerus. 
         FIG.  14    illustrates an example method in which a stemless humeral implant is implanted into the humerus. 
         FIG.  15    illustrates an example method in which an anatomical articular component is impacted onto the stemless humeral implant. 
         FIG.  16    illustrates an example method in which a reverse articular component is impacted onto the stemless humeral implant. 
         FIG.  17    illustrates an example method in which the humerus is drilled prior to reaming to facilitate preparation of a humerus of a patient with relatively hard bone. 
         FIG.  18    illustrates an example method in which the humerus undergoes a progressive reaming technique, expanding a recess in hard bone. 
         FIG.  19    illustrates an example method in which a portion of the humerus is reamed using a collar reamer to facilitate preparation of a humerus of a patient with relatively soft bone. 
         FIG.  20    illustrates an example method of compacting the humerus, to form a recess appropriately for a patient with relatively soft bone. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     This application is directed in various examples to novel and inventive shoulder implants and tools that can be used to implant them. The shoulder implants can be part of hemi- and total shoulder joint arthroplasty systems (as improvements of the systems illustrated in  FIGS.  1 A and  1 B , discussed below). In some cases the tools can be used with either a stemless anchor or an anchor that has a stem portion (forming an example of a stemmed humeral anchor) configured to extend into a diaphysis portion of a humerus. In some cases the tools can be used with anatomic shoulder configurations (e.g., as improvements to the tools used to arrive at the configuration of  FIG.  1 A ) and/or reverse shoulder configurations (e.g., as improvements to the tools used to arrive at the configuration of  FIG.  1 B ). These implants and tools can be used separately or can be combined in a system or kit that can even be provided in an operating room, allowing for intraoperative adaptation of a pre-operative plan to an enhanced surgical outcome that may only become fully apparent during the surgery, as discussed below. 
     I. Reverse and Anatomic Configurations for Total Shoulder Arthroplasty 
       FIGS.  1 A and  1 B  show two approaches to total shoulder arthroplasty.  FIG.  1 A  shows an anatomic approach in which the humeral head is replaced with an articular body  64  having a convex articular surface  65 . The glenoid of the scapula can be modified with an implant  67  providing a concave surface  68  for articulation of the humeral articular body  64  The humeral articular body  64  is secured to the humerus H using a stemless anchor  4  that is dedicated for and only compatible with the anatomic articular body  64 . 
       FIG.  1 B  shows a reverse approach in which the humerus H is fitted with an articular body  84  having a concave articular surface  85 . The glenoid region of the scapula is fitted with a spherical articular body, commonly called a glenosphere  87  (sometimes called a glenoid sphere). In this case, the concave articular surface  85  is placed on the humerus articulates of the glenosphere  87 , which is fixed relative to the scapula. The reverse articular body  84  is mounted to a tray  89  that is disposed between the reverse humeral articular body  84  and a stem anchor  83  that is surgically implanted in the humerus H. The humerus H is prepared by providing access to the medullary canal of the humerus H. 
     One can see that the anatomic and reverse approaches generally use different hardware to secure the articular components. So, switching from an anatomic to a reverse configuration involves extraction of the stemless anchor  4 . The bone stock that remains after such an extraction may or may not be suitable for supporting a stem anchor  83 . Also, the presence of the tray  89  requires more of the joint space. Thus, the reverse configuration may only be suitable for some patients with large joint space or following more invasive preparation of the humerus and/or the scapula. Fortunately the implants, tools, devices, systems and kits can reduce the need for conversion and revision surgeries which can be sub-optimal for patient outcomes. 
     II. Systems and Kits with Shared Implant Components 
       FIG.  2    is a schematic diagram of a total arthroplasty system comprising an arthroplasty kit  100  that can be used to perform anatomic or reverse arthroplasty, or to convert from one of anatomic to reverse or reverse to anatomic arthroplasty, according to various embodiments. The kit  100  can comprise one or a plurality of stemless humeral anchors  103 , one or a plurality of stemmed humeral anchors  113 , and one or a plurality of articular components  161 . The stemless humeral anchors  103  can have a tapered profile in which a distal portion  105  and a proximal portion  107  of the anchor  104 . The distal portion  105  of the anchors  103  shown in  FIG.  2    can have one or a plurality of fins  109  extending distally. The fins  109  can be configured to secure the anchors  103  into the humerus. 
     As shown in  FIG.  2   , the stemless anchors  103  can be provided in a plurality of sizes to accommodate patients of different sizes, different degrees of bone damage to the humerus, etc. In some embodiments, the lateral size of the stemless anchors  103  may vary so as to fit within different-sized resections of the humerus. For example, the kit  100  can comprise a plurality of stemless anchors  103 A,  103 B,  103 C,  103 D . . .  103   n , with n being the number of different sizes. Although four sizes are illustrated in  FIG.  2    (e.g., n=4, with anchors  103 A- 103 D), in other embodiments, the kit can include any suitable number of anchors. In some embodiments, a length  11  of the stemless anchors  103 A- 103 D may also vary so as to extend into the humerus by a depth that the clinician selects based on the particular patient being treated. Furthermore, and as explained below in connection with  FIG.  4 A , the anchors  103 A- 103 D can have different fin lengths  1   f  of the fins  109  to accommodate different sizes of the humerus. 
     In various embodiments, the fin lengths  1   f  of the anchors  103 A- 103 D can differ substantially so as to beneficially provide a wide range of anchor strengths to the humerus and accommodate patients with different levels of bone damage. In the arrangement of  FIG.  2   , for example, the first anchor  103 A can have the shortest overall length  11  and the shortest overall fin length  1   f . The fourth anchor  103 D can have the longest overall length  11  and the longest overall fin length  1   f . In various embodiments, a ratio of an overall length  11  of one anchor  103  (for example, the largest anchor  103 D) to an overall length  11  of another anchor  103  (for example, the smallest anchor  103 A) in the kit  100  can be in a range of 1.1 to 2.5, in a range of 1.15 to 2.5, in a range of 1.18 to 2.5, in a range of 1.2 to 2.5, in a range of 1.2 to 2, in a range of 1.2 to 1.8, in a range of 1.2 to 1.6, in a range of 1.3 to 1.6, in a range of 1.25 to 1.4, or in a range of 1.25 to 1.35 In some embodiments, the ratio of the overall length  11  of the fourth anchor  103 D to the overall length  11  of the second anchor  103 B can be in a range of 1.1 to 1.3, in a range of 1.15 to 1.25, or in a range of 1.15 to 1.2. In some embodiments, the ratio of the overall length  11  of the fourth anchor  103 D to the overall length  11  of the third anchor  103 C can be in a range of 1 to 1.2, in a range of 1.02 to 1.15, or in a range of 1.05 to 1.15. In some embodiments, the ratio of the overall length  11  of the second anchor  103 B to the overall length  11  of the first anchor  103 A can be in a range of 1 to 1.2, in a range of 1.02 to 1.15, or in a range of 1.05 to 1.15. In some embodiments, the ratio of the overall length  11  of the third anchor  103 C to the overall length  11  of the first anchor  103 A can be in a range of 1.1 to 1.3, or in a range of 1.15 to 1.25. In some embodiments, the ratio of the overall length  11  of the third anchor  103 C to the overall length  11  of the second anchor  103 B can be in a range of 1 to 1.2, in a range of 1.02 to 1.15, or in a range of 1.05 to 1.15. 
     In some embodiments, therefore, the kit  100  can include a plurality of sizes of anchors  103 A- 103 D, e.g., four sizes. In some embodiments, the first anchor  103 A can have a fin length  1   f  in a range of 3 mm to 7 mm, or in a range of 4 mm to 6 mm. The second anchor  103 B can have a fin length  1   f  in a range of 4 mm to 10 mm, in a range of 5 mm to 9 mm, or in a range of 6 mm to 8 mm. The third anchor  103 C can have a fin length  1   f  in a range of 7 mm to 10 mm, or in a range of 8 mm to 9 mm. The fourth anchor  103 D can have a fin length  1   f  in a range of 8 mm to 10 mm. In some embodiments, a ratio of the fin length  1   f  of the fourth anchor  103 D to the fin length  1   f  of the first anchor  103 A can be in a range of 1.5 to 2.5, in a range of 1.6 to 2, or in a range of 1.7 to 1.8. In some embodiments, the ratio of the fin length  1   f  of the fourth anchor  103 D to the fin length  1   f  of the second anchor  103 B can be in a range of 1.4 to 1.2, or in a range of 1.25 to 1.3. In some embodiments, the ratio of the fin length  1   f  of the fourth anchor  103 D to the fin length  1   f  of the third anchor  103 C can be in a range of 1 to 1.25, in a range of 1 to 1.1 or in a range of 1.02 to 1.1. In some embodiments, the ratio of the fin length  1   f  of the second anchor  103 B to the fin length  1   f  of the first anchor  103 A can be in a range of 1.1 to 1.6, in a range of 1.2 to 1.6 or in a range of 1.3 to 1.5. In some embodiments, the ratio of the fin length  1   f  of the third anchor  103 C to the fin length  1   f  of the first anchor  103 A can be in a range of 1.5 to 2, or in a range of 1.6 to 1.8. In some embodiments, the ratio of the fin length  1   f  of the third anchor  103 C to the fin length  1   f  of the second anchor  103 B can be in a range of 1.1 to 1.3, or in a range of 1.15 to 1.25. 
     The kit  100  can also include one or a plurality of stemmed humeral anchors  113 . The kit  100  can include one or more humeral stem anchors  112 , each of which includes a proximal metaphysis portion  120  and an elongate diaphysis portion  116  extending therefrom. The diaphysis portion  116  is sometimes referred to herein as a stem or stem portion. In some embodiments, the kit  100  can also include a trauma or fracture stem anchor  140 , which can be used in patients that have experienced a fracture of the humerus H. The stemmed humeral anchors  113  may be used in patients in which stemless anchors  103  may not be adequately secured to the humerus, for example, in patients that have experienced severe bone loss. The trauma or fracture stem may be used where the humerus has fractured into one or more pieces. As with the stemless anchors  103 , the kit  100  can include stemmed anchors  113  having a plurality of different sizes, e.g., different lateral sizes and/or different lengths  12 . For example, as shown in  FIG.  2   , the stemmed humeral anchors  113  can have respective lengths  12  that are longer than the lengths  11  of the stemless anchors  103 . Beneficially, the inclusion of differently-sized stemmed anchors  113  in the kit  100  can enable the clinician to select the appropriate size for a particular patient to ensure a secure implant of the anchor  113  into the patient, in view of the patient&#39;s bone size and health. In various embodiments, the lengths  12  of the stemmed humeral anchors can be in a range of 55 mm to 175 mm. By contrast, the shorter lengths  11  of the stemless humeral anchors  103  can be in a range of 16 mm to 28 mm. In various embodiments, stemmed humeral anchors  113 ,  140  can be configured to reach into the intramedullary canal of the humerus H for additional anchorage. 
     Beneficially, the kit  100  can comprise one or a plurality of shared humeral components that be used with either the stemless humeral implants  103  or the stemmed humeral implants  113 , depending on which implant  103  or  113  would be more appropriate for a particular patient&#39;s humeral anatomy. For example, the shared humeral components of the kit  100  can comprise a plurality of articular components or assemblies  161  that can be used in conjunction with either the stemless implants  103  or the stemmed implants  113 . As explained herein, both the stemless humeral anchors  103  and the stemmed humeral anchors  113  can include shared engagement features that can be used with the same set of tools and/or articular components. For example, as described herein, the stemless anchors  103  and stemmed anchors  113  can include convex and concave locking features configured to engage with the same set of articular components. 
     For example, the kit  100  can include an anatomic articular component  160  configured to mechanically couple to both the stemless humeral implants  103  and the stemmed humeral implants  113 . The clinician may select the anatomic articular component  160  for procedures in which an anatomic reconstruction is suitable. The anatomic articular component  160  can comprise a coupler  168  and an articular body  164  (anatomical) configured to mechanically engage the coupler  168 . As shown in  FIG.  2   , the articular body  164  for the anatomic articular component  160  can comprise a rounded, convex surface configured to engage a glenoid surface of the patient. The coupler  168  can serve to mechanically connect the anatomical articular body  164  (e.g., a rounded or essentially spherical surface) to either a stemless humeral implant  103  or a stemmed humeral implant  113 , depending on the patient&#39;s humeral bone structure. The articular body  164  and the coupler  168  can comprise a metal, such as cobalt, chrome, or titanium. In some embodiments, the articular body comprises a pyrocarbon layer on at least the articular surface. In various embodiments, the kit  100  can include anatomic articular components  160  having a plurality of sizes. 
     The kit  100  can also include a reverse articular component  180  configured to mechanically couple to both the stemless humeral implants  103  and the stemmed humeral implants  113 . The clinician may select the reverse articular component  180  for procedures in which a reverse anatomic reconstruction is suitable. The reverse articular component  180  can comprise a reverse articular body  184  and a locking device  188  configured to secure the reverse articular component  180  to a stemless humeral implant  103  or a stemmed humeral implant  113 , depending on the clinician&#39;s recommendation during the procedure. As shown, the reverse articular body  184  can comprise a rounded concave surface (e.g., essentially spherical) configured to engage with a glenosphere connected to the glenoid of the patient (not shown but in some cases combined with the kit into a larger surgical kit). In addition, in some embodiments, the kit  100  can include a wear resistant reverse articular component  180 A, which may be generally similar to the reverse articular component  180  but may further be formed to include vitamin E to promote long-term compatibility with the patient&#39;s bone structure. The reverse components  180 ,  180 A can comprise a polymer, including, for example, ultra high molecular weight polyethylene. In various embodiments, the kit  100  can include reverse articular components  180 ,  180 A having a plurality of sizes. 
     During an arthroplasty procedure, the clinician may inspect the bone structure of the humerus and/or the scapula to determine whether the anatomy is suitable for a stemless or stemmed humeral anchor, and whether the anatomy is suitable for an anatomical or reverse anatomical reconstruction. Beneficially, the kit  100  shown in  FIG.  2    can provide the clinician with a total arthroplasty system including components that are compatible with stemless or stemmed anchors, and with anatomical or reverse anatomical constructions. For example, during a procedure, the clinician may observe that the patient has sufficient humeral bone structure so that a stemless anchor  103  may be used to reduce the damage to the patient&#39;s anatomy. The clinician may also elect whether to proceed with an anatomical reconstruction or a reverse construction, and can accordingly select either the anatomical articular component  160  or the reverse articular component  180 ,  180 A. 
     Similarly, if during a shoulder arthroplasty procedure, the clinician determines that the patient&#39;s bone structure is damaged or otherwise more suited to a stemmed anchor  113 , then the clinician can select an appropriately sized stemmed anchor 
       113 . The clinician can further select whether to proceed with an anatomical reconstruction or a reverse construction, and can accordingly select either the anatomical articular component  160  or the reverse articular component  180 ,  180 A. Beneficially, the kit  100  of  FIG.  2    includes interchangeable or interoperable components that can be used in stemmed or stemless anchors, and with anatomical or reverse anatomical reconstructions. Because the shared humeral articular components  161  (e.g., anatomical or reverse anatomical articular bodies) can be used with either the stemless or stemmed anchors  103 ,  113 , the clinician can make, or change, reconstruction decisions during surgery. The kit  100  can accordingly enable the clinician to quickly determine the reconstruction procedure most suitable for a patient and can provide the clinician with the components to be used for that reconstruction procedure. 
     As explained above, for humeral fractures, the kit  100  can also include one or more trauma stems  140 . Beneficially, the trauma stem(s)  140  can include engagement features generally similar to or the same as the engagement features in the stemless anchors  103  and humeral stem anchors  112 , such that the stemless anchors  103 , the humeral stem anchors  112 , and the trauma stem(s)  140  can be used with a common set of shared articular components  161  and tools. Beneficially, therefore, the kit  100  can provide a shared set of implantation tools and a shared set of articular components  161  that can be used with either stemless or stemmed humeral anchors  103 ,  113 , and that can be used for anatomical or reverse anatomical reconstructions. 
     In some embodiments, the coupler  168  can comprise a proximal extension  163 A configured to connect to the articular body  164  and a distal extension  163 B. The distal extension  163 B for the fracture stem  140  can be received within a recess  217  of the fracture stem  140  for anatomical reconstructions. The disc or middle portion  162  disposed between the proximal extension  163 A and the distal extension  163 B can be eliminated since the recess  217  is elevated toward the resection plane. In a modified embodiment, the recess  217  is recessed from (e.g., extends distally from) a distal end of a second recess. In those embodiments, the disc or middle portion  162  provides a spacer function in use in the trauma stem  140 . Additional details of trauma stems may be found throughout International Application No. PCT/US2015/065126, filed Dec. 15, 2015, the entire contents of which are hereby incorporated by reference herein in their entirety and for all purposes. 
     III. Examples of Humeral Anchors 
     As noted above, this application discloses some kits and systems that provide shared components and that may include multiple types of humeral anchors. The humeral anchors can include stemless anchors, anchors with stem portions (examples of stemmed humeral anchors), and fracture anchors that can have stems. 
     A. Stemless Humeral Anchor Examples 
     Some stemless humeral anchor examples disclosed herein includes features for enhanced metaphyseal retention and/or features for enhanced articular component connection or retention. These features can increase the percentage of patients in a patient population that can benefit from a stemless approach, which is generally less invasive than a stemmed approach. 
       FIGS.  3 - 3 C  illustrate an example of a stemless humeral anchor  203 . Unless otherwise noted, the components of  FIGS.  3 - 3 C  may be the same as or generally similar to like-numbered components of  FIG.  2   , with the reference numerals incremented by 100. In  FIGS.  3 - 3 A- 1   , the stemless humeral anchor  203  is shown as being connected to (or prior to being connected to) an articular component  161 , which can comprise the anatomical articular component  160  or the reverse articular component  180 . In  FIG.  3   , the stemless humeral anchor  203  is shown connected to the anatomical articular body  164  of the anatomical articular component  160 . In  FIG.  3 A , the stemless humeral anchor  203  is shown connected to the reverse articular body  184  of the reverse articular component  180 . The articular component  161  can be an articular assembly, e.g., a polymeric articular body and a locking component such as a locking ring. 
     As shown in  FIGS.  3 A- 1 - 3 C , a first recess  231  can extend distally from a proximal end  239  of the humeral anchor  203  and into the proximal portion  207 . The first recess  231  can be sized and shaped to receive a distal or lateral portion of the articular component  161 , including the reverse articular body  184  and a locking device  288 . As shown in  FIG.  3 C , the first recess  231  can be disposed in the proximal portion  207  of the anchor  203 . The proximal portion  207  can be defined at least in part by a first proximal exterior surface  211 . A second recess  232  can extend distally from the first recess  231  into a first section  205 A of the distal portion  205  of the anchor  203 . The second recess  232  can be sized and shaped to receive the distal extension  163 B of the coupler  168  for connecting the anatomic articular component  160  to the stemless humeral anchor  203 . The first and second recesses  231 ,  232  can have different volumes. For example, the volume of the first recess  231  (and/or a diameter or major lateral dimension of the first recess  231 ) can be larger than the volume of the second recess  232  (and/or a diameter or major lateral dimension of the second recess  232 ). Thus, the combined space formed by the recesses  231 ,  232  can be larger toward the proximal end  239  of the anchor  203  and smaller toward a distal end  37  of the anchor  203 , as shown, e.g., in  FIG.  3 C . 
     The first section  205 A of the distal portion  205  can be defined at least in part by a second distal exterior surface  212 , and can be dimensioned to occupy a portion of a metaphysis of the humerus when implanted. A second section  205 B of the distal portion  205  can comprise the one or more fins  209  configured to extend farther into the metaphysis than the first section  205 A to secure the anchor  203  to the humerus. As shown in  FIG.  3 C , the second recess  232  can be tapered inwardly to engage the coupler  168 , e.g., a tapered surface portion of the distal extension  163 B thereof. One or a plurality of blind holes  245  can also extend distally from a distal interior surface  235  of the proximal portion  207  bounding the distal end of the first recess  231  into the second section  205 B of the distal portion  205 . The blind holes  245  can engage a tool that enables insertion of the humeral anchor  203  into the humerus. An example of a tool that can engage the blind holes  245  is discussed below in Section IV(A) and Section IV(B). As shown in  FIGS.  3 A- 1  and  3 C , the blind holes  245  can extend distally at angled inwardly towards the interior second recess  232 . 
     The anchor  203  can include an inner periphery  233  disposed about the first recess  231  adjacent to the proximal end  239  of the humeral anchor  203 . The inner periphery  233  can be a surface portion extending from the distal interior surface  235  to the proximal end  239  of the humeral anchor  203 . The inner periphery  233  can include one or a plurality of concave locking features  243  disposed in the inner periphery  233  and one or a plurality of convex locking features  241  disposed in the inner periphery  233 . As shown in  FIGS.  3 A- 1 - 3 C , in one example where both are provided, the concave locking feature  243  can be circumferentially spaced apart from the convex locking feature  241 . Further, in the embodiment of  FIGS.  3 A- 3 C , the anchor  203  includes a plurality, e.g., two or a pair, of concave locking features  243 A,  243 B spaced apart from one another along the inner periphery  233 . The locking features  243 A,  243 B can be disposed opposite one another across the recess  231  on the inner periphery  233 . In some embodiments, as shown in  FIG.  3 B , a first concave locking feature  243 A can be disposed at a medial portion M of the humeral anchor  203 , and a second concave locking feature  243 B be disposed at a lateral portion L of the humeral anchor  203 . In some examples, a first concave locking feature  243 A can be disposed at an anterior portion of the humeral anchor  203  and a second concave locking feature  243 B be disposed at a posterior portion of the humeral anchor  203 . The first concave locking feature  243 A and the second concave locking feature  243 B be disposed opposite one another on the inner periphery  233 . An angle can be defined between the first and second locking features  243 A,  243 B, e.g., 180 degrees, 120 degrees, 90 degrees, 60 degrees or other angular separation therebetween. More than two locking features  243 A or  243 B can be provided, e.g., three at 120 degree spacing, four at 90 degree spacing, six at 60 degree spacing. The spacing between the locking features  243 A,  243 B can be unequal in some embodiments. 
     The concave locking features  243  can comprise a curved surface extending radially outward relative to the inner periphery  233 . The concave locking features  243 A,  243 B can be sized relative to locking features of the articular component  161  that provides an interference connection between the articular component  161  and the locking features  243 A,  243 B. Such interference fit can include an aspect of the concave locking features  243 A,  243 B being smaller than a corresponding exterior surface of the articular component  161 . 
     A plurality, e.g., two or a pair, of convex locking features  241 A,  241 B can also be disposed opposite one another along the inner periphery  233 . In some embodiments, as shown in  FIG.  3 B , a first convex locking feature  241 A can be disposed at an anterior portion A of the humeral anchor  203 , and a second opposing convex locking feature  241 B be disposed at a posterior portion P of the humeral anchor  203 . The convex locking feature  241  can comprise a projection  247  extending radially inward relative to the inner periphery  233  towards the first recess  231 . The projection  247  can be elongate with a longitudinal direction oriented proximal-distal in the first recess  231 , e.g., parallel to a direction of insertion of the articular component  261 . The projection  247  can extend toward a central portion of the first recess  231  from an adjacent portion of the periphery  233 . Portions of the periphery  231  adjacent to the projection  247  can be concave in structure facing toward the first recess  231  relative to the projection  247 . For example, the convex locking feature  241  can be adjacent to a pair of concave recesses  242  formed in the inner periphery  233 . As with the concave locking features  243 A,  243 B, the convex locking features  241 A,  241 B can be sized relative to corresponding locking features of the articular component  161  that provides an interference connection between the articular component  161  and the convex locking features  241 A,  241 B. Such an interference fit can include an aspect of the convex locking features  241 A,  241 B being smaller than a corresponding exterior surface of the articular component  161 , for example, the projection  247  can extend into and engage a corresponding locking feature of the articular component  161 . 
     A circumferential groove  244  can extend circumferentially along the inner periphery  233 . The groove  244  can comprise a plurality of segments disposed circumferentially between concave locking feature  243 A and convex locking feature  241 A, between concave locking feature  243 A and convex locking feature  241 B, between concave locking feature  243 B and convex locking feature  241 A, and between concave locking feature  243 A and convex locking feature  241 B. The groove  244  can comprise any suitable number of segments, for example, four, six, etc. As explained below, the groove  244  can be sized relative to the locking feature  288  of the articular component  161  to provide a snap or interference fit with the locking feature  288 . In various embodiments, the groove  244  can comprise a distally-facing surface that can secure the locking feature  288  of the articular component  161  to the anchor  203 . 
     The clinician can insert the articular component  161  (e.g., the reverse articular component  180  shown in  FIG.  3 A- 1   ) into the first recess  231  of the stemless humeral anchor  203  to secure the articular component  161  to the anchor  203 . The locking feature  288  of the articular component  161  can comprise convex tabs  252  spaced apart from one another, for example, on opposite sides of the articular component  161 . The locking feature  288  can also comprise concave slots  251  spaced apart from one another. A locking ring  253  can be disposed circumferentially within a groove of the articular component  161 . A distal projection  254  can extend distally from the locking feature  288  to engage the stemless humeral anchor  203  in the second recess  232 . 
     When the clinician inserts the articular component  161  into the first recess  231 , the clinician can align the articular component  161  relative to the first recess  231  such that the convex tabs  252  engage with the corresponding concave locking features  243  of the anchor  203  and such that the concave slots  251  engage with the corresponding convex locking features  241  of the anchor  203 . The tabs  252 , slots  251 , concave locking features  243 , and convex locking features  241  can be dimensioned such that, upon insertion of the articular component  161  into the first recess  231 , an interference or friction fit is formed between the reverse articular component  180  and the humeral anchor  203 . The concave locking features  243  and convex locking feature  241  can serve as anti-rotation features to inhibit relative rotation between the anchor  203  and the articular component  161 . The locking ring  253  can extend into the circumferential groove  244  of the anchor  203 . The locking ring  253  can serve to lock the articular component  180  into the anchor  203  and to prevent the articular component  161  from translating vertically outward from the anchor  203 . 
       FIG.  3 B  shows the connection of the articular component  161  (such as a reverse articular component  180 ) to the anchor  203 . The outer periphery of the articular component  161  can be seen inside the inner periphery  233  of the anchor  203 . As explained above, the tabs  252  can engage the concave locking features  243 A,  243 B of the anchor  203  in an interference fit. Similarly, the concave slots  251  of the articular component  161  can engage the projections  247  of the convex locking features  241 A,  241 B in an interference fit. Although not illustrated in the view of  FIG.  3 B , the locking ring  253  can fit within the groove  244  of the inner periphery  233 . 
     In embodiments where one or a plurality of locking features have different configurations, the rotational position can be more easily confirmed intra-operatively. For example, the tabs  252  can be visually confirmed to be rotationally positioned correctly relative to the concave locking features  243 A,  243 B. By providing two opposite tabs  252 , only two rotational positions can result in securing the articular component  161  to the anchor  203 . In some cases, these two positions provide identical biomechanics of the shoulder joint when assembled. The two positions are rotationally symmetric. In other embodiments the two positions provide two options for biomechanics such that the surgeon can select among two positions of the articular component  180  relative to the anchor  203 . In a first rotation position, a tab  252 A is positioned in a superiorly positioned concave recess  243 A and a tab  252 B is positioned in an inferiorly positioned concave recess  243 B. In a second rotational position, the tab  252 A is positioned in the inferiorly positioned concave recess  243 B and the tab  252 B is positioned in the superiorly positioned concave recess  243 B. 
     In various embodiments, the proximal end  239  of the humeral anchor  203  can comprise a collar or rim  266  configured to be positioned against the humerus. As explained below in connection with the stemmed humeral anchor  1200  of  FIG.  6 C , the rim  266  can comprise a cancellous bone compression member, which can include a bone compression surface. The bone compression surface of the stemless anchor  203  can be generally similar to the bone compression member shown in  FIG.  6 C . For example, the bone compression surface can be disposed adjacent to or at the proximal end  239  of the humeral anchor  203  and can be disposed about a medial side of the proximal portion  203 . As with  FIG.  6 C , the bone compression surface can be disposed about only the medial side, e.g., about a portion of the periphery of the proximal end  239  not including the lateral side of the humeral stem. The bone compression member of the stemless anchor  203  may include features generally similar to those described below in connection with  FIG.  6 C . 
     For example, as with the stemmed anchor  1200  of  FIG.  6   , the cancellous bone compression member of the stemless anchor  203  can be made for a patient in a patient specific manner. For example, in various embodiments, the shoulder of the patient (e.g., the humerus and/or glenoid) can be imaged during pre-operative imaging procedures. The cancellous bone compression member of the stemless anchor  203  can be shaped to specifically match the patient&#39;s anatomy based on the imaging performed before surgery. For example, in various embodiments, the cancellous bone compression member can be manufactured using various types of additive manufacturing techniques such as three-dimensional (3D) printing. The image data representative of the patient&#39;s cancellous bone structure can be transmitted to 3D printing machinery which can manufacture the cancellous bone compression member to substantially match or conform to the patient&#39;s cancellous bone tissue. The member can be shaped to extend at least to an inner wall portion of a cortical bone layer. The member can be shaped to extend beyond an inner wall portion of a cortical bone layer. The member can be shaped to follow the shape of the periphery of the humerus at the resection surface. These configurations can be made patient specific to reduce, minimize or eliminate stress shielding and concomitant bone loss. Accordingly, various embodiments disclosed herein can beneficially provide patient-specific structures to improve the fit of the anchor within the humerus. 
       FIGS.  4 A- 4 G  illustrate various features of the exterior surface of humeral anchors. For example,  FIG.  4 A  is a schematic side view of a stemless humeral anchor  303 . The humeral anchor  303  can be the same as or different from the humeral anchors  103 ,  203  of  FIGS.  2 - 3 C . Unless otherwise noted, the components of  FIG.  4 A  may be the same as or generally similar to like-numbered components of  FIGS.  3 - 3 C , with the reference numerals incremented by 100 relative to the reference numerals of  FIGS.  3 - 3 C . As shown in  FIG.  4 A , the proximal portion  307  of the stemless humeral anchor  303  can include a first proximal exterior surface  311 . A first section  305 A of the distal portion  305  of the stemless humeral anchor  303  can include the second distal exterior surface  312 . The first proximal exterior surface  311  can be wider than the second distal exterior surface  312 . For example, the first proximal exterior surface  311  can be disposed about the first recess  331 . The second distal exterior surface  312  can be disposed about the second recess (for example, the second recess  232  shown in  FIG.  3 C ). In various embodiments, a ratio of a first width of the proximal portion  307  (for example, as measured at opposing locations of the first proximal exterior surface  311 ) to a second width of the first distal section  305 A (for example, as measured at opposing locations of the second distal exterior surface  312 ) can be in a range of 1.2 to 2, in a range of 1.2 to 1.8, in a range of 1.25 to 1.8, in a range of 1.3 to 1.75, in a range of 1.3 to 1.7, or in a range of 1.3 to 1.6. Such ratios of first to second widths can beneficially serve a bone-filling function to secure the anchor  302  to the humerus. 
     In the illustrated embodiment, as explained above, both the first and second surfaces  311 ,  312  can serve a bone filling function, e.g., the respective widths of the first and second surfaces  311 ,  312  can be sufficiently large so as to fill and secure the anchor  302  to the humerus. In some embodiments, the first proximal exterior surface  311  can be tapered inwardly. In other embodiments, the first exterior surface  311  can comprise a straight or generally cylindrical surface. The first exterior surface  311  can form a right cylinder relative to the proximal end  339  of the humeral anchor  303 . In other words the first exterior surface  311  extends perpendicular to a plane that includes the proximal end  339  of the anchor  303 . In other embodiments, the first exterior surface  311  can be tapered inwardly. The surface  311  can be oriented at an angle of 5 degrees from perpendicular from the plane that includes the proximal end  339  of the anchor  303 . The surface  311  can be oriented at an angle between 1 degree and 10 degrees from perpendicular from the plane that includes the proximal end  339  of the anchor  303 . In various embodiments, the second distal surface  312  can comprise a straight or generally cylindrical surface. For example, the surface  312  can also be oriented perpendicular to a plane that includes the proximal end  339  of the anchor  303 . In other embodiments, the second exterior surface  312  can be tapered inwardly. For example, the second surface  312  can be oriented at an angle of 5 degrees from perpendicular from the plane that includes the proximal end  339  of the anchor  303 . The surface  312  can be oriented at an angle between 1 degree and 10 degrees from perpendicular from the plane that includes the proximal end  339  of the anchor  303 . 
     As explained above in connection with  FIGS.  3 - 3 C , the fins  309  of the second distal section  305 B can extend distally from the first distal section  305 A to a distal end of the humeral anchor  303 . The fin length if can be sufficiently long so as to reduce, minimize or eliminate rotation of the anchor  303  within the metaphysis upon application of a load, e.g., a torque, to an articular component coupled with the anchor. In various embodiments, for example, the fin length  1   f  can be at least 10% of the overall first length  11  of the humeral anchor  303 , at least 11% of the overall first length  11  of the humeral anchor  303 , at least 20% of the overall first length  11  of the humeral anchor  303 , at least 24% of the overall first length  11  of the humeral anchor  303 , at least 28% of the overall first length  11  of the humeral anchor  303 , at least 29% of the overall first length  11  of the humeral anchor  303 , at least 30% of the overall first length  11  of the humeral anchor  303 , at least 31% of the overall first length  11  of the humeral anchor  303 , at least 33% of the overall first length  11  of the humeral anchor  303 , or at least 34% of the overall first length  11  of the humeral anchor  303 . In various embodiments, the fin length  1   f  can be in a range of 8% to 40% of the overall first length  11  of the humeral anchor  303 , in a range of 10% to 40% of the overall first length  11  of the humeral anchor  303 , in a range of 11% to 40% of the overall first length  11  of the humeral anchor  303 , in a range of 20% to 25% of the overall first length  11  of the humeral anchor  303 , in a range of 25% to 35% of the overall first length  11  of the humeral anchor  303 , in a range of 20% to 40% of the overall first length  1  of the humeral anchor  303 , in a range of 20% to 35% of the overall first length  1  of the humeral anchor  303 , in a range of 24% to 40% of the overall first length  11  of the humeral anchor  303 , in a range of 30% to 40% of the overall first length  11  of the humeral anchor  303 , in a range of 8% to 35% of the overall first length  11  of the humeral anchor  303 , or in a range of 30% to 35% of the overall first length  11  of the humeral anchor  303 . Moreover, one or a plurality of radial projections  306  can extend radially outward from the humeral anchor  303 . As shown, for example, the radial projections  306  can extend outwardly from the second distal surface  312 . The radial projections  306  can enhance the connection of the humeral anchor  303  to the humerus. The radial projections  306  can be tapered inwardly and distally as shown. 
       FIG.  4 B  is a bottom view of the stemless humeral anchor  303  of  FIG.  4 A . In the embodiment of  FIG.  4 B , the anchor  303  can comprise three (3) fins  309 A,  309 B, and  309 C. As shown in  FIG.  4 B , fin  309 C can be oriented along an inferior direction I. Fin  309 A can be oriented diagonally so as to have respective directional components along an anterior direction A and a superior direction S. Fin  309 B can be oriented diagonally so as to have respective directional components along a posterior direction P and the superior direction S. As shown the fins  309 A- 309 C can be evenly spaced apart, for example, by about 120°. The directions inferior I, superior S, anterior A, and posterior P each corresponding to a direction of a humerus of a patient when any of the anchors  303 ,  403 ,  503 , are applied. During implantation, the clinician can orient the humeral anchor  303  in this manner and can insert the anchor  303  into the humerus with the illustrated orientation. This orientation may beneficially improve the anchoring of the implant to the humerus because the orientation of the anterior-superior and posterior-superior fins have more surface area facing a direction more likely to be subject to a tilt out force. 
       FIGS.  4 C- 4 C- 2    illustrate another example of a stemless humeral anchor  403 , in which a fin structure extends along an entire length of the anchor  403 .  FIG.  4 C  is a side view of the anchor  403 .  FIG.  4 C- 1    is a top view of the anchor  403 .  FIG.  4 C- 2    is a side sectional view of the stemless humeral anchor  403  taken along section  4 C- 2 - 4 C- 2  of  FIG.  4 C- 1   . Unless otherwise noted, the components of  FIGS.  4 C- 4 C- 2    may be the same as or generally similar to like-numbered components of  FIG.  4 A , with the reference numerals incremented by 100 relative to the reference numerals of  FIG.  4 A . For example, as with  FIG.  4 A , the anchor  403  of  FIGS.  4 C- 4 C- 2    includes a distal fin  409  extending from a first distal section  405 A to a distal end of the anchor  403 . Moreover, the anchor  403  includes a radial projection  406 B extending radially outward from the second distal surface  412 . In addition, the anchor  403  can include an additional radial projection  406 A extending radially outward from the first proximal surface  411 . The projections  406 A,  406 B can be tapered inwardly and distally. In the illustrated embodiment, moreover, the projections  406 A,  406 B may be shaped so as to define a continuous surface with one another and with the fin  409 . For example, as shown in  FIGS.  4 C and  4 C- 2   , the fin  409  and the projections  406 A,  406 B may cooperate to define a radially- and distally-extending fin structure having a common outer rib  418 . As shown, the fins  409  and projections  406 A,  406 B can have rounded edges. The radially- and distally-extending fin structure can extend from a collar  438  at the proximal end  439  of the anchor  403  to the distal end of the anchor  403 , e.g., the distal end of the fin  409 . Beneficially, the use of the elongated fin structure of  FIGS.  4 C- 4 C- 2    can improve the securement of the anchor  403  to the humerus. 
       FIG.  4 D  illustrates another example of a stemless humeral anchor  503 . Unless otherwise noted, the components of  FIG.  4 D  may be the same as or generally similar to like numbered components of  FIGS.  4 A- 4 C- 2   , with the reference numerals incremented by 100. In the embodiment of  FIG.  4 D , the first exterior surface  511  and the second exterior surface  512  can comprise cylindrical surfaces with vertical sidewalls, e.g., sidewalls that are perpendicular to the collar  538  at the proximal end  539  of the anchor  503 . A width of the proximal portion  507 , which can be defined at least in part by the first exterior surface  511 , can have a first width. A width of the first distal section  505 A, which can be defined at least in part by the second exterior surface  512 , can have a second width that is less than the first width. In various embodiments, the second width can be less than the first width in a range of about 0.5 mm to about 4 mm, in a range of about 1 mm to about 3 mm, or in a range of about 1.5 mm to about 2.5 mm, for example, by about 2 mm. 
       FIG.  4 D- 1    is a side view of a humeral anchor  603 , according to another embodiment. The humeral anchor  603  may be generally similar to the humeral anchor  503  of  FIG.  4 D . For example, the anchor  603  can have a fin structure that extends from the collar  638  at the proximal end  639  to the distal end of the anchor  603 . Moreover, the proximal portion  607  and the first distal section  605 A can have straight cylindrical profiles. In the embodiment of  FIG.  4 D- 1   , a porous material  649  can be provided on at least a portion of the fin structure. For example, in the illustrated embodiment, the porous material  649  can be provided along the radial projections  606 A,  606 B, in addition to the exterior surfaces  611 ,  612  of the proximal and first distal sections  607 ,  605 A. The porous material  649  can be provided to foster ingrowth of bone tissue into the radial projections  606 A,  606 B. In other embodiments, the porous material  649  can also be provided on the fins  609 . 
       FIG.  4 E  is a schematic side view of a stemless humeral anchor  703 , according to another embodiment. Unless otherwise noted, the components of  FIG.  4 E  may be the same as or generally similar to like-numbered components of  FIG.  4 D- 1   , with the reference numerals incremented by 100 relative to the reference numerals of  FIG.  4 D- 1   . In the embodiment of  FIG.  4 E , a plurality of teeth  719  can be provided on the first proximal surface  711  and/or on the second distal surface  712 . In various embodiments, multiple teeth  719  can be provided on each of the first and second surfaces  711 ,  712 . In other embodiments, teeth  719  may be provided on only one of the first and second surfaces  711 ,  712 . As shown, each of the teeth  719  can comprise a proximally oriented face, surface, or extent. The teeth  719  can assist in securing the anchor  703  to the humerus. In various embodiments, the teeth  719  can comprise a metal.  FIG.  4 E  shows that the teeth  719  can include one or a plurality of arcuate projections disposed around one or both of the surfaces  711 ,  712 . The teeth  719  can include ring-like projections in some examples. The teeth  719  can include proximally larger and distally smaller structures. The teeth  719  can include a plurality of aligned ring-like structures, e.g., two, three, four or more ring-like projections on one and/or both of the surfaces  711 ,  712 . One or more or all of the teeth  719  can present a proximally oriented surface that will engage bone matter and resist allowing the anchor  703  to back out of the humerus under expected operational loads. 
       FIG.  4 F  is a schematic side view of a humeral anchor  803 , according to another embodiment.  FIG.  4 F- 1    is a schematic bottom view of the stemless humeral anchor  803  of  FIG.  4   -F. Unless otherwise noted, the components of  FIGS.  4 F- 4 F- 1    may be the same as or generally similar to like-numbered components of  FIG.  4 E , with the reference numerals incremented by 100 relative to the reference numerals of  FIG.  4 E . Unlike the embodiment of  FIG.  4 E , in  FIGS.  4 F- 4 F- 1   , the anchor  803  includes four (4) fins  809 A,  809 B,  809 C, and  809 D. Fin  809 A can be oriented diagonally relative to the anatomy so as to have respective directional components along the anterior direction A and the superior direction S. Fin  809 B can be oriented can be oriented diagonally relative to the anatomy so as to have respective directional components along the posterior direction P and the superior direction S. Fin  809 C can be oriented diagonally relative to the anatomy so as to have respective directional components along the posterior direction P and the inferior direction I. Fin  809 D can be oriented diagonally relative to the anatomy so as to have respective directional components along the anterior direction A and the inferior direction I. As shown the fins  809 A- 809 D can be evenly spaced apart, for example, by about 90°. The configuration of the anchor  803  is advantageous in providing one-third more surface area of engagement with the cancellous bone of the metaphysis of a humerus to which the anchor  803  is applied. Also, all four fins  809 A- 809 D are positioned to resist a tilt out force in a direction more likely to be subject to such a force. Thus, with only one-third more fins, the tilt out resistance can be roughly doubled compared to the configuration and orientation of the anchor shown in  FIG.  4 B . 
       FIG.  4 G  is a side view of a humeral anchor  903  according to various embodiments. Unless otherwise noted the components shown in  FIG.  4 G  may be the same as or generally similar to like numbered components of  FIGS.  4 A- 4 F- 1   , with the reference numerals incremented by 100 relative to  FIGS.  4 F- 4 F- 1   . In the embodiment of  FIG.  4 G , the first distal section  905 A may be smaller than the bowl-shaped first distal sections  505 A and  605 A of  FIGS.  4 D- 4 D- 1   . The proximal portion  907  and the first distal section  905 A may comprise straight cylindrical profiles with walls that are perpendicular to the collar  938  at the proximal end  939  of the anchor  903 . The width of the proximal portion  907  can be at least 1 mm, at least 1.5 mm, or at least 2 mm larger than the width of the first distal section  905 A. The narrow first distal section  905 A can enhance the area of a fin  909  at the level of the distal section  905 A in direct contact with bone matter when the anchor  903  is implanted. The anchor  903  of  FIG.  4 G  can comprise a bone-preserving stemless anchor in which the distal section  905 A of the distal portion  905  is narrower than the distal portion of other anchors disclosed herein. The narrower distal section  905 A can enable the use of fin(s)  909  having increased surface area. By increasing the surface area of the fin  909  contacting the bone, the anchor  903  can be less susceptible to a lever-out force or other load that could potentially dislodge the anchor  903 . 
     The size of the distal section  905 A can be made sufficiently large enough, however, to receive the distal extension  163 B of the coupler  168 . In some embodiments, the width or size of the distal section  905 A can be made slightly larger than the width of the distal extension  163 B in a plurality of the sizes of anchors  903  in a kit. As explained above, in some kits, multiple sizes of stemless anchors  903  may be provided. In various embodiments, the widths of the proximal portion  907  and the distal portion  905  of the anchors  903  (e.g., the exterior surfaces  911 ,  912  and fin(s)  909 ) in a kit may vary so as to fit within differently-sized bone structures, but the width of the second or distal recess (similar to the second recess  232 ) may be about the same for each sized anchor  903  in the kit (or may vary only slightly). In some embodiments, a width of the second or distal recess for each anchor  903  in the kit may differ by less than 15%, less than 10%, less than 5%, or less than 1% of the width of a particular anchor  903  of the kit. 
     In the embodiment of  FIG.  4 G , a ratio of a first width of the first proximal recess (similar to the first recess  231 ) to a second width of the second distal recess (similar to the second recess  232 ) can be in a range of 2:1 to 3.25:1, in a range of 2.2:1 to 3.1:1, or in a range of 2.25:1 to 3:1. As explained above, in some embodiments, the widths of the second distal recesses of each anchor  903  of a kit may be about the same, or may vary only slightly. The first widths of the first proximal recesses of the anchors  903  of the kit may differ such that a ratio of the first width of the first proximal recess (similar to the first recess  231 ) of the largest anchor  903  in the kit to the first width of the first proximal recess of the smallest anchor  903  in the kit is in a range of 1.2 to 1.5, in a range of 1.25 to 1.45, or in a range of 1.3 to 1.4. 
     B. Examples Humeral Anchors with Stem Portions 
     For some patients it is preferred to provide enhanced or different anchorage of a humeral implant within the humerus H. The bone quality in the metaphysis M may be such that a stemless anchor would not provide adequate tilt out performance or would not be expected to sufficiently integrate with the bone. As such, an anchor with a distal portion adapted to reach to the diaphysis D of the humerus H may be a good choice for a patient. 
       FIG.  5    shows an example of a humeral stem  1190  that has a distal portion that can extend into the diaphysis D of the humerus H. The positioning of the humeral stem  1190  can be challenging. For example, it may be desired that a lateral side of a proximal end of the humeral stem  1190  (upper left side in  FIG.  5   ) abut, engage or touch the cortical bone Co layer. This can provide a predictable performance of the humeral stem  1190  in the humerus H. Meanwhile, the medial side of the proximal end of humeral stem  1190  (upper right side in  FIG.  5   ) may be spaced from the cortical bone Co due to the non-circular shape of the resected humerus H. More particularly, the distance from supero-lateral edge of the resection to the infero-medial edge of the resection may be larger than the diameter of the metaphysis portion of the humeral stem  1190  at the proximal end of the humeral stem  1190 . As such, a portion of the cancellous bone Ca at the arrow A will not be engaged by the humeral stem  1190  and will be exposed following implantation of the humeral stem  1190 . Although the cancellous bone Ca at the arrow A may be somewhat compressed by the method of inserting the humeral stem  1190  (discussed further below), the non-engaged state of the cancellous bone Ca at this location may result in disadvantageous processes such as stress shielding leading to resorption of the bone. 
       FIGS.  6 A- 6 M  illustrate various examples of a humeral stem  1200  that can be implanted in a resected humerus H. The humeral stem  1200  can be provided in the kit  100  as one of the plurality of stemmed humeral anchors  113 . Any one or more of the features of the humeral stem  1200  can be incorporated into the humeral stem  1190 , which can be provided in the kit  100 . 
       FIG.  6 A  shows that the humeral stem  1200  includes a metaphysis portion  1202  and a diaphysis portion  1204 . The metaphysis portion  1202  is configured to be placed in the metaphysis M of a humerus H and the diaphysis portion  1204  is configured to be placed in the diaphysis D of the humerus H (see  FIG.  5   ). The metaphysis portion  1202  has a larger area in any given cross-section thereof than the diaphysis portion  1204 . The metaphysis portion  1202  is generally configured to occupy a large volume of the metaphysis M similar to the construction of the stemless anchors discussed above. In some cases, the metaphysis portion  1202  has an overall volume that is equal to or exceeds that of a corresponding size stemless implant in the kit  100 . The diaphysis portion  1204  may be tapered in way that periphery will match and generally file the shape and volume of an intramedullary canal of the humerus H. At least the metaphysis portion  1202  has a cancellous bone interface  1206 . The cancellous bone interface  1206  can include a portion of the outer surface of the humeral stem  1200  that is disposed and configured to touch the cancellous bone Ca and to provide a desired result between the humeral stem  1200  and the cancellous bone Ca or a function of preserving the cancellous bone Ca. In some cases, the cancellous bone interface  1206  includes a porous zone  1208  that is configured to provide or enhance bone in-growth in the humeral stem  1200 . The porous zone  1208  can be a texture or a surface with pores sized to encourage bone matter to grow therein or thereon. The cancellous bone interface  1206  can include a cancellous bone compression member  1210  that is configured to reduce or minimize the effects of stress shielding. 
       FIG.  6 B  shows a proximal and medial aspect of the humeral stem  1200 . This aspect includes an articular body interface  1212 . The articular body interface  1212  is a portion to which an articular body, such as a reverse should implant articular body can be coupled. As will be discussed in greater detail below, the articular body interface  1212  can include features that receive and engage features of such an articular body, as discussed further below. The articular body interface  1212  can be located at a proximal end of the humeral stem  1200 . The articular body interface  1212  can include indicia for directing a surgeon in orienting an articular body insert. The humeral stem  1200  also can include a tooling interface  1213 . The tooling interface  1213  can be similar to the blind holes  245  discussed above in connection with the stemless humeral anchor  203 . In some cases the kit  100  includes tools that can be used for both humeral stems and stemless anchors, as discussed below in connection with  FIGS.  7 - 20   . For such kits  100  the tooling interface  1213  can be identical between the humeral stem  1200  and a stemless implant as described above in connection with  FIGS.  3 A- 4 G . 
     A good outcome following implantation of the humeral stem  1200  in the humerus H will be the retention of the stem in a fixed position in the humerus H. An anti-rotation member  1214  seen in  FIGS.  6 A and  6 B  can reduce motion of the humeral stem  1200  in the humerus H, in particular rotation about a longitudinal axis  1222  of a distal portion  1216  of the humeral stem  1200 . The anti-rotation member  1214  can be disposed in the metaphysis portion  1202 . The anti-rotation member  1214  can extend along the metaphysis portion  1202  toward the diaphysis portion  1204 .  FIG.  6 A  shows that the humeral stem  1200  can have a porous portion generally corresponding to the metaphysis portion  1202  and a smooth portion extending from a distal end  1218  of the humeral stem  1200  toward the metaphysis portion  1202 . The anti-rotation member  1214  can include a first portion extending into a porous portion and a second portion in the smooth portion. The anti-rotation member  1214  can extend continuously from the porous metaphysis portion  1202  into a transition region between the metaphysis portion  1202  and the diaphysis portion  1204 . 
       FIG.  6 B  shows that the anti-rotation member  1214  can project from anterior and posterior zones of reduced volume. The anterior and posterior zones can be configured as proximally enlarged flutes which can accommodate volumes of preserved humeral bone below the resection plane. The anterior and posterior zones can be seen as concave profiles on a medial half of the body of the humeral stem  1200  from the anti-rotation member  1214  toward the lateral half of the humeral stem  1200 . The anterior and posterior zones preserve humeral bone compared to a configuration where the flutes are not present, e.g., where the humeral stem  1200  is continuously convex in the region of the anti-rotation member  1214 . 
       FIGS.  6 A- 6 J  further show that the humeral stem  1200  can include a distal portion  1216  that extends along the longitudinal axis  1222  proximally from the distal end  1218 . The distal portion  1216  is tapered inwardly along the longitudinal axis  1222  toward the distal end  1218  of the humeral anchor  1200 . The humeral stem  1200  includes a proximal portion  1226 . The proximal portion  1226  extends distally from a proximal end  1230  of the humeral anchor humeral stem  1200 . The humeral stem  1200  includes an outer surface  1234 . The outer surface  1234  in the proximal portion  1226  is enlarged to occupy at least a majority of the volume of a metaphysis of the humerus into which the humeral anchor is to be disposed. The outer surface  1234  in the distal portion  1216  can be slender to fit within an intramedullary canal without substantial preparation thereof. The outer surface  1234  can be porous in part and can be smooth in part. 
     The humeral stem  1200  includes a lateral side  1238 . The lateral side  1238  is configured to be disposed adjacent to a cortical wall of a lateral portion of a humeral metaphysis. As discussed further below a humerus can be prepared by resection and by reaming and broaching to prepare a space therein. In one approach the lateral side  1238  of the humeral stem  1200  is configured to be disposed adjacent to a lateral cortical bone wall or segment, e.g., an inner surface of a cortical bone layer. Such placement provides a consistent anatomic reference in the humerus in some techniques. Such placement allows a medial side  1242  to be consistently spaced relative to a medial cortical wall. For example, the medial side  1242  or a method of implanting the humeral stem  1200  can be configured to cause the medial side  1242  to be spaced apart from the medial cortical wall. Such spacing allows preserves the medial cortical wall such that the humeral stem  1200  is not likely to break through the medial cortical wall when the humeral stem  1200  is applied to the patient. 
       FIGS.  6 A and  6 C  provide additional details of the cancellous bone compression member  1210  in various examples. The cancellous bone compression member  1210  can include a bone compression surface  1250 . The bone compression surface  1250  can be disposed adjacent to or at the proximal end  1230  of the humeral anchor  1200 . In one example, the bone compression surface  1250  is disposed about the medial side  1242  of the proximal portion  1226 . The bone compression surface  1250  can be disposed about only the medial side  1242 , e.g., about a portion of the periphery of the proximal end  1230  not including the lateral side  1238  of the humeral stem  1200 . The cancellous bone compression member  1210  is configured to extend from the medial side  1242  of the proximal portion to the cortical wall of the medial side of the humeral metaphysis when implanted in a humerus.  FIG.  5    shows a gap at the arrow A between the medial side of the humeral stem  1190  and the inside surface or wall of the cortical bone Co. The bone compression surface  1250  can be configured to bridge the gap or space left by the humeral stem  1190 . By closing the gap shown at the arrow A bone loss due to stress shielding can be reduced, minimized or even eliminated. This can result in a more stable, long lasting implant and also can reduce, minimize or even eliminate instances of revision surgery which can be traumatic and in some cases not even possible for aging patients. 
     The bone compression surface  1250  can comprise a distal facing side of a flange  1258 . The flange  1258  can extend outward from the proximal end  1230  of the proximal portion  1226  of the humeral stem  1200 . The shape of the outer periphery of the flange  1258  can be any suitable shape. For example, the flange  1258  can have a circular outer periphery  1266 . The circular outer periphery  1266  can have a radius corresponding to a radius of the lateral side of the proximal portion  1226  of the humeral stem  1200 . The proximal end  1230  of the humeral stem  1200  can have an annular face with a circular shape. A radius of the circular shape can extend to the same lateral position as the lateral side  1238  of the proximal portion  1226  adjacent to the annular face. A radius of the circular shape can extend farther medially than the medial side  1242  of the proximal portion  1226  adjacent to the annular face. This can provide an overhang configuration of the bone compression surface  1250  on the medial side  1242  and less or no bone compression surface on the lateral side  1238 . A result of this configuration is that the width of the bone compression surface  1250  can taper at least at one and in some cases at both opposing ends thereof until the bone compression surface  1250  is not present, e.g., from about 10 o&#39;clock to about 2 o&#39;clock as seen in  FIG.  6 C . In the illustrated embodiment, the bone compression surface  1250  is present in more than one-half of the periphery of the cancellous bone compression member  1210 . The bone compression surface  1250  can be present in less than one-half of the periphery of the cancellous bone compression member  1210 , e.g., only between 8 o&#39;clock and 4 o&#39;clock in one example. The bone compression surface  1250  could be present entirely around the proximal end  1230  with a varying width, e.g., with a lesser width on the lateral side  1238 . 
     In a further example, the configuration of the cancellous bone compression member  1210  can be made for a patient in a patient specific manner. For example, in various embodiments, the shoulder of the patient (e.g., the humerus and/or glenoid) can be imaged during pre-operative imaging procedures. The cancellous bone compression member  1210  can be shaped to specifically match the patient&#39;s anatomy based on the imaging performed before surgery. For example, in various embodiments, the cancellous bone compression member  1210  can be manufactured using various types of additive manufacturing techniques such as three-dimensional (3D) printing. The image data representative of the patient&#39;s cancellous bone structure can be transmitted to 3D printing machinery which can manufacture the cancellous bone compression member  1210  to substantially match or conform to the patient&#39;s cancellous bone tissue. The member  1210  can be shaped to extend at least to an inner wall portion of a cortical bone layer. The member  1210  can be shaped to extend beyond an inner wall portion of a cortical bone layer. The member  1210  can be shaped to follow the shape of the periphery of the humerus at the resection surface. These configurations can be made patient specific to reduce, minimize or eliminate stress shielding and concomitant bone loss. Accordingly, various embodiments disclosed herein can beneficially provide patient-specific structures to improve the fit of the anchor within the humerus. 
       FIG.  6 B  shows that the humeral stem  1200  can have an annular surface  1274  disposed at a proximal face  1278  of the humeral anchor. The flange  1258  can comprise a portion of the annular surface  1274  of the proximal face  1278 . In some cases, the flange  1258  includes the bone compression surface  1250  on one side and the annular surface  1274  disposed on the opposite side thereof. The annular surface  1274  can include indicia helpful in orienting an articular component or assembly relative to the humerus of the patient. The annular surface  1274  can include rotational orientation indicia  1282  formed on or in the annular surface  1274  disposed at the proximal face  1278  of the humeral anchor  1200 . In the illustrated embodiment, the rotational orientation indicia  1282  are numbers in the form of a clock face to indicate twelve discrete rotational positions. While this form of the rotational orientation indicia  1282  is intuitive, the indicia can be fewer or more numbers, letters, colors or other indicia or combination of indicia. In some cases, an articular assembly or component to be coupled with the humeral stem  1200  is asymmetric such that the rotational position thereof relative to the humeral stem  1200  changes the bio-mechanics of the assembly. The indicia on the annular surface  1274  can guide the surgeon on placing the articular assembly or component, as discussed further below. In brief, the indicia on the humeral stem  1200  (whether a trial implant or a final implant) can be used during a trial for a group of articular components or assemblies to indicate a desired position. Then, when the final implant is initially placed in the opened joint space the indicated orientation can be replicated prior to permanent connection of the final articular component or assembly with the humeral stem  1200 . 
       FIGS.  6 D-F  show details of the proximal portion  1226 , in particular features for connecting an articular component or articular assembly therewith. The humeral stem  1200  includes a recess  1286  that extends distally from the proximal end  1230  of the humeral stem  1200  and into the proximal portion  1226 . The recess  1286  can be surrounded by an inner periphery  1290  disposed about the recess  1286 . The inner periphery  1290  can be disposed adjacent to the proximal end  1230  of the humeral anchor  1200 . The inner periphery  1290  can be a circular wall facing toward the center of the recess  1286 . The inner periphery  1290  can include one or more features to engage an articular component, such as a reverse polymer insert or an anatomic articular assembly. The inner periphery  1290  can include a locking feature  1294  disposed in the inner periphery  1290 . The locking feature  1294 , e.g., a concave locking feature  1296 A, is aligned with the bone compression surface  1250 . The locking feature  1294  can have a structure similar to locking features discussed above in connection with the stemless humeral anchor  203  in  FIGS.  3 A- 3 C . In one embodiment, the locking feature  1294  comprises a concave locking feature  1296  disposed in the inner periphery  1290 . The concave locking feature  1296  can be configured to provide an interference fit for or with an articular body, such as a reverse shoulder implant articular body. The concave locking feature  1296  can include a first concave locking feature  1296 A and a second concave locking feature  1296 B. The second concave locking feature  1296 B is disposed opposite the first concave locking feature  1296 A. The first concave locking feature  1296 A and the second concave locking features  1296 B are disposed at medial and lateral portions of the humeral stem  1200  respectively in one embodiment. 
     The locking feature  1294  can include a convex locking feature  1298  disposed in the inner periphery  1290 . The concave locking feature  1298  can be spaced apart from the convex locking feature  1296 . In one embodiment, the convex locking feature  1298  includes a first convex locking feature  1298 A and a second convex locking feature  1298 B disposed opposite the first convex locking feature  1298 A, e.g., at anterior and posterior positions. The convex locking feature  1298  can include an elongate fin  1299  projecting toward the recess  12986 . The elongate fin  1299  can be configured to engage a periphery of an articular component, as discussed further below. 
     The profile of the humeral stem  1200  can be configured for a combination of snug fit in the diaphysis D of a humerus H and for enhanced engagement with bone in a metaphysis M of the humerus H. The distal portion  1216 , e.g., the diaphysis portion  1204  can include a circular periphery  1300  at a first location  1304  along the longitudinal axis  1222  of the humeral anchor  1200  adjacent to the distal end  1218 , as shown in  FIG.  6 I . The first location  1304  can be disposed along a length  1308 . The length  1308  can have one or more circular peripheries disposed along the length  1308 , e.g., from the distal end  1218  to or beyond the first location  1304 . 
     The profile of the humeral stem  1200  can change from circular at or adjacent to the distal end  1218  to an oblong periphery  1316  at a second location  1320  disposed between the first location  1304  and the proximal end  1230  of the humeral stem  1200 , as shown in  FIG.  6 J . The oblong periphery  1316  can include a first dimension  1324  in an anterior-posterior direction and a second dimension  1328  in a medial lateral direction. The second dimension  1328  is larger than the first dimension  1324 . In one configuration, the oblong profile at the second location  1320  can provide a circular periphery, e.g., with the same radius or a larger radius than the radius at the first location  1304  at a lateral side of the humeral stem  1200  and a second curved profile on the medial side of the humeral stem  1200 . For example, the second curved profile can be of a smaller radius of curvature or can be a non-circular shape such as oval or ellipse so that the medial side of the humeral stem  1200  occupies more space medially when disposed in the humerus H than does the lateral side of the circular curvature. The second location  1320  can be proximal of the first location  1304 . 
       FIGS.  6 E and  6 L  show that further proximal of the second location  1320 , an at least partially polygonal periphery  1332  can be provided at a third location  1336 . The third location  1336  can be disposed between the second location  1320  and the proximal end  1230  of the humeral anchor  1200 . The at least partially polygonal periphery  1332  can be disposed in a cross-section oriented at an angle  1338  to the longitudinal axis  1222  of the distal portion  1216  and parallel to the proximal end  1230  of the humeral anchor  1200 . The sides of the at least partially polygonal periphery  1332  can include a portion  1332 A with a smaller medial-lateral dimension from a widest anterior-posterior dimension to a lateral side of the periphery  1332  and a portion  1332 B with a larger medial-lateral dimension from a widest anterior-posterior dimension to a medial side of the periphery  1332 . Thus the humeral stem  1200  can extend farther and fill more volume in the medial direction at the third location  1336  than in the lateral dimension. This is consistent with the approach to align the lateral side of the humeral stem  1200  with a projection of the intramedullary canal and to have the medial side project medially to fill a more complex space defined between a lateral cortical bone wall and a medial cortical bone wall. The position of the recess  1286  is seen to be shifted medially of the widest part of the at least partially polygonal periphery  1332 . 
       FIGS.  6 E and  6 K  show that between the third location  1336  and the second location  1320  there can be a second at least partially polygonal periphery  1354 . The periphery  1354  can be disposed at a fourth location  1358  between the second location  1320  and the proximal end  1230  of the humeral anchor  1200 . The second at least partially polygonal periphery  1354  can include a curved convex side configured to be oriented laterally. The second at least partially polygonal periphery  1354  can include a more anterior-posterior oriented side  1342  disposed between ends of the portion  1332 B. Between the fourth location  1358  and the second location  1320  the humeral stem  1200  can transition from a configuration in which the lateral portion thereof has a smaller curvature, e.g., is more curved, and the medial portion thereof has a larger curvature, e.g., is flatter than the lateral portion, (see  FIG.  6 K ) to a configuration in which the lateral portion thereof has a larger curvature, e.g., is flatter, and the medial portion thereof has a larger curvature, e.g., is more curved than the lateral portion (see  FIG.  6 L ). This transition can be mostly a result in a change in curvature on the medial side reflecting a higher volume of bone to fill on the medial side when the stem is maintained straight or superior-inferior, e.g., along a direction corresponding to a projection of the lateral inner cortical wall of the intramedullary canal. 
     An anti-rotation fin  1370  can be disposed along one or more sides of the humeral stem  1200 . In one embodiment, the anti-rotation fin  1370  is disposed along a medial side of the humeral stem  1200 . The anti-rotation fin  1370  can be found in the at least partially polygonal periphery  1332  adjacent to the proximal end  1230  in one embodiment. The anti-rotation fin  1370  can be found in the second at least partially polygonal periphery  1354  in one embodiment. In one embodiment, the anti-rotation fin  1370  includes a projection  1378  that can extend in a medial direction from the generally anterior-posterior oriented side or portion of the second at least partially polygonal periphery  1354 . The anti-rotation fin  1370  can extend continuously from the at least partially polygonal periphery  1338  at the third location  1336  to the second at least partially polygonal periphery  1354  at the fourth location  1358 . The anti-rotation fin  1370  can emerge as the humeral stem  1200  transitions from a generally round profile in the length  1308  extending proximally from the distal end  1218  to a medially extended configuration, e.g., to a at least partially polygonal periphery between the first location  1304  and the proximal end  1230 . 
     The anti-rotation fin  1370  is important in maintaining the stability of the humeral stem  1200  in the humerus H. Stability of the humeral stem  1200  is important to prevent dislocation of the implant, which if severe can result in revision surgery, which is a sub-optimal outcome for patients. Even where revision surgery is not required, movement of the humeral stem  1200  can change the biomechanics of the shoulder joint post-surgically. As discussed above, in some combinations an articular component is coupled with the humeral stem  1200  in a rotational position that provides prescribed biomechanics. Rotation of the humeral stem  1200  relative to the humerus H changes the angles between the arm and the scapula, which shifts the biomechanics from that which was prescribed. This can result in sub-optimal arm motion, which can lead to fatigue, injury, damage to the scapula, e.g., avoidable scapular notching, and in an extreme case the need for unwanted revision surgery. 
       FIG.  6 M  is a side view of a humeral stem anchor  1400  having an extended distal portion providing a length L. As with the embodiments of  FIGS.  6 A- 6 L , the anchor  1400  can comprise a proximal portion  1426  and a distal portion  1416 . The distal portion  1416  can comprise an elongate stem  1404  extending from the proximal portion  1426 . As explained above, the proximal portion  1426  can comprise shared locking or engagements features with the stemless and stemmed humeral anchors described above, such that the anchor  1400  can be used with anatomical articular components and reverse articular components. The anchor  1400  of  FIG.  6 M  can have a length L which may be suitable for larger patients or for patients with higher degrees of bone damage or intraoperative fractures. In various embodiments, the length L of the anchor  1400  of  FIG.  6 M  can be in a range of 120 mm to 200 mm, in a range of 130 mm to 180 mm, or in a range of 140 mm to 160 mm. Table 1 below illustrates example lengths for standard stem lengths, long stem lengths, and extra-long stem lengths. 
     IV. Shoulder Arthroplasty Methods and Instrumentation 
     The humeral anchors described above can be implanted following methods discussed below in connection with  FIGS.  7 - 21   . These methods can advantageously employ certain tools and instruments that can be shared among the stemless anchors and the anchors with stems. This provides advantages in reducing the training required to complete a surgical procedure. 
     A. Methods of Implanting Humeral Anchors 
       FIGS.  7 - 16    illustrate a method of preparing a humerus H to receive implant components and assemblies disclosed herein. The method can be used with bone of typical hardness and bone quality. 
     A resection step  1500  is performed in an initial part of the method. The resection step  1500  involves applying an intramedullary cutting block assembly  1504  to the humerus H. The resection step  1500  can include an intramedullary rod  1506  that can be advanced into a proximal end of the humerus H, e.g., through a lateral portion of an articular surface of the humerus H. The intramedullary rod  1506  can have a depth stop  1508  disposed at a proximal end thereof. The depth stop  1508  can be configured to limit the advancement of the intramedullary rod  1506  to a selected extent. The intramedullary cutting block assembly  1504  can also have a handle extending proximally from the depth stop  1508 . The handle can have one or more markings and apertures to aid in the process of placing the intramedullary cutting block assembly  1504 , e.g., aligning the assembly with the humerus H. The intramedullary cutting block assembly  1504  can include a cross-arm  1512  that extends laterally from the handle. The cross-arm  1512  can be positioned rotationally about a longitudinal axis of the intramedullary rod  1506 . The intramedullary cutting block assembly  1504  also can include a boom  1516  that extends therefrom to hole a cutting block  1520  in a proper position. For example, the cutting block  1520  can be suspended at an anatomic neck of the humerus H. In some procedures, it is desired to resect the humerus H at the anatomic neck to separate the articular surface of the humerus H from the rest of the humerus. The separation of the articular surface from the rest of the humerus H creates a resection surface seen, for example, in  FIG.  8   . 
     In some cases, a surgeon may prefer not to insert the intramedullary rod  1506  into the humerus H and may prefer to use an extramedullary cutting block assembly  1524 . The extramedullary cutting block assembly  1524  includes a cutting block  1520 A that is similar to the cutting block  1520 . The cutting block  1520 A is supported from below, e.g., with a mounting block member that can be pinned to an external cortical wall surface of the diaphysis of the humerus H. The extramedullary cutting block assembly  1524  has an advantage in that there is no rod passing through the plane of the resection. The intramedullary cutting block assembly  1504  has an advantage in that there is no need to drill any holes in any part of the humerus H that will remain following the surgery. 
       FIG.  8    shows that following resection, an optional protect step  1540  can be performed. In the protect step  1540  the resected surface that was formed in the resection step  1500  can be protected while other aspects of the surgery are on-going. It is important to protect the newly exposed cancellous bone Ca because this bone is to be formed in later parts of the method to have a recess having an inner profile that matches the outer or exterior and distal surface of any of the anchors (e.g., the stemless anchor or the metaphysis portion of the stemmed anchors). The protect step  1540  can be performed by applying a protect tool  1542  to the resected surface to cover the cancellous bone Ca. The protect tool  1542  can include a protect plate  1544 . The protect plate  1544  can have one or a plurality, e.g., two spikes  1548  extending from a bone facing (distal or medial) side of the protect plate  1544 . The spikes  1548  can be sharp enough at their distal end to allow the spikes  1548  to be pressed into the cancellous bone Ca. The protect plate  1544  can include one or a plurality of, e.g., two, handling apertures  1552  disposed therein. The handling apertures  1552  can extend entirely through the protect plate  1544  in one embodiment. The handling apertures  1552  can be gripped by a tool, such as would be similar to the scissors tool shown in  FIG.  13   . Once the protect step  1540  is complete, other aspects of the method can follow. 
       FIG.  9    shows a sizing step  1572  that can be subsequently performed. The protect tool  1542  can optionally be removed prior to the sizing step  1572 . In the sizing step  1572  a handle and sizer assembly  1576  is placed against the resected humerus at the exposed cancellous bone Ca. The handle and sizer assembly  1576  can enable a determination of which size of the stemless humeral anchor  103  (or other anchor as disclosed or claimed herein) should be used for the particular patient. For example, the handle and sizer assembly  1576  can have a number  1 ,  2 ,  3 , or  4  on a face thereof that corresponds to four similarly labeled or numbered sizes. The handle and sizer assembly  1576  preferably have an aperture formed therein for placement of a guide pin  1580 . The guide pin  1580  can be advanced through the aperture in the handle and sizer assembly  1576  and into the cancellous bone Ca at the resection surface and thereafter sufficiently deep into the humerus H to be stable for subsequent procedures. 
       FIG.  9   , lower image, shows another example of a handle and sizer assembly  1576 A. The handle and sizer assembly  1576 A includes a head sizer  1584  and a handle  1588 . The head sizer  1584  can have the same form as an anatomical articular body, e.g., with a convex surface facing away from the resection and a planar surface facing the resection. The head sizer  1584  provides a very clear visual confirmation of how an anatomic head would sit on the resection surface. The handle  1588  can include a projection  1590  that can be advanced into a keyed opening in the head sizer  1584 . The connection between the projection  1590  and the keyed aperture can be a snug fit so that simple hand force can be used to insert the handle  1588  into the head sizer  1584  and also remove the head sizer  1584  from the handle  1588 . The snug fit can provide a retention force that is sufficient to prevent the head sizer  1584  from falling off the handle  1588  so that the surgeon can use the handle  1588  to place the head sizer  1584  on the resected surface and remove the head sizer  1584  from that surface without more complex tools like graspers. The handle  1588  can have a concave side periphery that can be shaped to at least partially receive the convex curvature of the surgeon&#39;s fingers making the handle  1588  comfortable and easy to grip. The handle  1588  can have a pin aperture  1592  formed therethrough. The pin aperture  1592  can have a length from a proximal side of the handle  1588  to a distal side thereof through the projection  1590 . The length can be sufficient to accurately guide the guide pin  1580  into the humerus H through the cancellous bone Ca exposed at the resection. 
     After the pin has been placed the handle and sizer assembly  1576 ,  1576 A can be removed over the proximal end of pin leaving the pin in place. 
       FIG.  10    shows a reaming step  1600  that can follow the resection step  1500 . The reaming step  1600  optionally is performed over the guide pin  1580  so it can also follow the sizing step  1572  or another step in which a pin is placed in some examples After the reamer is advanced toward the bone, the reaming step  1600  can be used to form a recess or cavity C in the cancellous bone Ca of the humerus H that is exposed by the resection step  1500 . The reaming step  1600  can produce a stepped internal recess or cavity C in the metaphysis of the humerus H shaped to receive a humeral anchor portion, e.g., the stemless anchor  103  or a metaphysis portion of a stemmed anchor. The cavity C may include a first or proximal cavity portion and a second or distal cavity portion extending to a greater depth into the bone than the first cavity portion. The distal portion of the cavity may have a reduced diameter compared to the proximal portion. The cavity C may also include a stepped portion between the first portion and the second portion of the cavity. The recess can be rotationally symmetric in some examples, such that a reamer assembly including a reaming head  1604  and a driver shaft  1608  can be used to form the recess. The reaming head  1604  may also form a recessed surface R below the resection plane P of the bone. The recessed surface may be proximal of and at least partially surround the cavity C. The recessed surface R and the cavity C may be formed simultaneously (e.g., using reaming head  1800 ) or formed sequentially (e.g., using reaming heads  1850 A, B). The reaming head  1604  can be configured to be removably attached to the driver shaft  1608  to enable selection of one of a plurality of size of reaming head  1604  to be used with a common driver shaft  1608 . The size of the reaming head  1604  corresponds to the size determined in the sizing step  1572  in some examples. One or both of the reaming head  1604  and the driver shaft  1608  are cannulated to enable the direction of reaming to be controlled by the orientation of the guide pin  1580 . 
       FIGS.  10 A- 10 B  illustrate example reaming heads that may be used in the reaming step  1600 . 
       FIG.  10 A  illustrates a reaming head  1800  having a first or proximal end  1802  and a second or distal end  1804 . The reaming head  1800  includes a drive shaft  1822  at the first end  1802 . The drive shaft  1822  is configured to be removably attached to the driving mechanism. The driving mechanism is configured to rotate the reamer head  1800  about a drive shaft axis X to remove bone. The reaming head  1800  may also include an indicator  1808  positioned near the first end  1802 . The indicator  1808  may provide an indication of size. Different sized reamers may correspond to different sized anchor. The indicator may be a color indicator, numeral indicator, or other indicator. 
     The reamer head  1800  includes a proximal portion  1810  and a distal portion  1814 . The proximal portion  1810  includes a proximal face  1824  of the reaming head  1800 . The proximal face  1824  includes one or more apertures  1826  extending therethrough and visible by the surgeon during the procedure so the surgeon may visualize the bone region being reamed. The apertures  1826  enable bone material to be evacuated from the reamer during reaming. The apertures  1826  may also reduce the total weight of the reaming head  1800 . The proximal portion  1810  may include a depth stop  1836  configured to control an insertion depth of the reamer head  1800 . 
     The proximal portion  1810  includes a distal facing cutting edge  1812 . The distal facing cutting edge  1812  include a plurality of teeth extending circumferentially around the proximal portion  1810  of the reaming head  1800 . The distal facing cutting edge  1812  is configured to form a recessed surface R with respect to the resection plane P (see  FIG.  10   ). The depth stop  1836  may project radially outward of the distal facing cutting edge  1812  such that the depth stop may be seated on the resection plane P when the distal facing cutting edge  1812  forms the recessed surface R. 
     The distal facing cutting edge  1812  defines an inner periphery  1830  and an outer periphery  1828 . A thickness of the recessed surface R corresponds to a thickness of the distal facing cutting edge  1812  measured between the inner periphery  1820  and the outer periphery  1828 . The distal facing cutting edge  1812  does not remove any material interior to the inner periphery  1820 . When the anchor is implanted, the proximal end of the anchor (e.g., proximal end  239  of anchor  203 ) is configured to be seated on the recessed surface R formed by the distal facing cutting edge  1812 . 
     The distal portion  1814  of the reaming head  1800  extends distally from the proximal portion  1810  of the reaming head  1800 . The entire distal portion  1814  may be within the inner periphery  1820  of the proximal portion  1800 . The distal portion  1814  forms the cavity C extending distally from the recessed surface R (see  FIG.  10   ). The cavity C is also positioned radially inward of the recessed surface R. 
     As shown in  FIG.  10 A , the distal portion  1814  includes a plurality of radial arms  1818  extending radially outward from a central region of the reaming head  1800 . The plurality of radial arms  1818  may be circumferentially spaced apart from each other. Each radial arm  1818  is defined by a first flat face  1832  and a second flat face  1834  opposite the first flat face  1832 . The first flat face  1832  and the second flat face  1834  are separated by a thickness. A width of each of the flat faces  1832 ,  1834 , measured in a radial direction, is greater than the thickness of each arm  1818 . The thickness of each radial arm  1818  forms a lateral cutting edge  1820 . The lateral cutting edge  1820  has a different profile than the distal cutting edge  1812 . For example, the distal cutting edge  1812  may include a plurality of teeth or a serrated edge, while lateral cutting edge  1820  forms a blade edge. 
     The distal portion  1814  may be configured to form the two-stage cavity C. As explained above, the cavity C may include a proximal portion and a distal portion extending at a greater depth than the proximal portion. The two-stage cavity C is formed by the shape of the lateral cutting edges  1820 . Each lateral cutting edge  1820  includes a proximal section defined by a first cutting edge  1820   a . The first cutting edge  1820   a  may be parallel to or angled with respect to the drive shaft axis X. The first cutting edge  1820   a  forms the proximal portion of the cavity C. 
     The lateral cutting edge  1820  includes a distal section defined by a second cutting edge  1820   b . The second cutting edge  1820   b  terminates at a sharped end at the second end  1804  of the reamer head  1800 . The second cutting edge  1820   b  is positioned radially inward of the first cutting edge  1820   a . The second cutting edge  1820   b  may be parallel to or angled with respect to the drive shaft X. The second cutting edge  1820  may be parallel to or angled with respect to the first cutting edge  1820   a . The second cutting edge  1820   b  forms the distal portion of the cavity C. 
     The first cutting edge  1820   a  may be separated from the second cutting edge  1820   b  by a stepped portion  1820   c . The stepped portion  1820   c  projects inward from the first cutting edge  1820   a  and toward the second cutting edge  1820   b . The transition between the first cutting edge  1820   a  and the stepped portion  1820   c  may form a rounded corner or a sharp corner. The transition between the stepped portion  1820   c  and the second cutting edge  1820   b  may form a rounded corner or a sharp corner. The stepped portion  1820   c  may form an annular ledge between the proximal portion of the cavity and the distal portion of the cavity. 
     The reaming head  1800  may include a guide channel  1816  configured to receive a guide pin. The guide channel  1816  extends through the second end  1804  of the reaming head and is centrally located with respect to the radial arms  1818 . 
       FIG.  10 B  illustrates another reaming head system configured to form the cavity C shown in  FIG.  10    but in a two-part form. The reaming head system includes a first reaming head  1850 A and a second reaming head  1850 B. The first reaming head  1850 A and the second head reaming head  1850 B may include any of the features of the reaming head  1800 . Each of the first reaming head  1850 A and the second reaming head  1850 B is configured to be removably attached to the drive mechanism. The drive mechanism is configured to rotate the reaming heads  1850 A,  1850 B about the drive shaft axis X to remove bone. Each reaming head  1850 A,  1850 B may be driven about a guide pin to enable the direction of reaming to be controlled by the orientation of the guide pin. 
     The first reaming head  1850 A is configured to form the recessed surface R and the proximal portion of cavity C (see  FIG.  10   ). As shown in  FIG.  10 B , the first reaming head  1850 A includes a proximal portion  1860  and a distal portion  1864 . In use, the first reaming head  1850 A may be used first to form the recessed surface R and the proximal portion of the cavity C. Thereafter, the second reaming head  1850 B may be used to form distal portion of the cavity C and the stepped portion between the proximal portion and the distal portion of the cavity C. 
     The proximal portion  1860  includes a proximal face  1874 . The proximal face  1874  may include one or more apertures  1876  extending therethrough and visible by the surgeon during the procedure. The proximal portion  1860  may include a depth stop  1886  configured to control an insertion depth of the reamer head  1850 A. The proximal portion  1860  also includes a distal facing cutting edge  1862  configured form the recessed surface R with respect to the resection plane P (see  FIG.  10   ). The distal facing cutting edge  1862  may have a similar profile to the distal facing cutting edge  1812 . 
     The distal portion  1864  of the first reaming head  1850 A may be configured to form the proximal portion of the cavity C. The distal portion  1864  extends distally from the proximal portion  1860 . The entire distal portion  1864  may be within the inner periphery of the proximal portion  1860 . As shown in  FIG.  10 B , the distal portion  1864  includes a plurality of radial arms  1868  extending radially outward from a central region of the reaming head  1850 A. The plurality of radial arms  1868  may be circumferentially spaced apart from each other. Each radial arm  1868  forms a lateral cutting edge  1870   a . The lateral cutting edge  1870   a  may be parallel to or angled with respect to the drive shaft axis X. Each radial arm  1868  may also include a distal edge  1870   b  extending radially inward from the lateral cutting edge  1870   a . The distal edge  1870   b  may be planar or angled with respect to a transverse axis perpendicular to the drive shaft axis X. 
     The second reaming head  1850 B includes a proximal portion  1861  and a distal portion  1865 . The proximal portion  1861  includes a distal facing cutting edge  1863 . The distal facing cutting edge  1863  includes a plurality of teeth configured to form an annular ledge between the proximal portion of the cavity C and the distal portion of the cavity C (see  FIG.  10 A ). The distal facing cutting edge  1863  includes an inner periphery and an outer periphery. A diameter of the outer periphery of the distal facing cutting edge  1863  may be no greater than a diameter of the distal portion  1864  of the reaming head  1850 A. 
     The distal portion  1865  may be configured to form the distal portion of the cavity C. The distal portion  1865  extends distally from the proximal portion  1861 . The entire distal portion  1865  may be within the inner periphery of the proximal portion  1861 . The distal portion  1865  of the second reaming head  1850 B may have a reduced diameter compared to the distal portion  1864  of the first reaming head  1850 A. As shown in  FIG.  10 B , the distal portion  1865  includes a plurality of radial arms  1869  extending radially outward from a central region of the reaming head  1850 B. The plurality of radial arms  1869  may be circumferentially spaced apart from each other. Each radial arm  1869  forms a first lateral cutting edge  1871   b , which may be parallel to or angled with respect to the drive shaft axis X. Each radial arm  1869  may also include a distal edge  1871   b  extending radially inward from the laterally cutting edge  1871   b . The distal edge  1871   b  may be planar or angled with respect to a transverse axis perpendicular to the drive shaft axis X. 
       FIG.  11    shows an optional blazing step  1900 . The blazing step  1900  can follow the reaming step  1600  in order to more precisely form the recess formed in the reaming step  1600 . For example, it is desired that the humeral anchors disclosed herein (e.g., the stemless anchor  103  or humeral stem  1200 ) be placed in a controlled manner such that a collar or annular member (e.g., the bone compression surface  1250 ) sits flush on a prepared portion of the cancellous bone at or below the resection surface, and such that fin(s) (e.g., fins  309 ) can be easily implanted into the humerus. If the shape of the recess is only somewhat close to that of the outer surface of the anchor, and/or if the shape of the recess does not accommodate the outer surface of the fins, the anchor may not sit flush on the humerus. Moreover, without a pathway along which to insert the fin(s), it can be challenging to securely implant the fins(s) into the humerus. The blazing step  1900  uses a blazer  1904  and a stem impactor-inserter  1908  to compress the cancellous bone exposed in the reaming step  1600  so that the shape of the wall around the recess in the humerus H matches the shape of the anchor exterior wall in the metaphysis portion thereof. Moreover, the blazer  1904  can form pathways or channels into which the fin(s) can be inserted. The blazer  1904  can also serve as a body into which a trial anchor is placed. 
     The blazer  1904  can be very similar to the anchor that it is intended to prepare the recess in the humerus H to receive. It can have the same exterior surface of the anchor, for example. The blazer  1904  also can have the same tooling interface so that the stem impactor-inserter  1908  can be used for the blazing step  1900  and for impacting the anchor into the humerus H, as discussed below in connection with  FIG.  14   . The stem impactor-inserter  1908  is described in greater detail below, but in general the stem impactor-inserter  1908  can have one or a plurality of impaction heads. When provided with a plurality of impaction heads, the stem impactor-inserter  1908  can allow a single tool to be used for the blazing step  1900  regardless of whether the surgeon prefers a stemless or a stemmed implant. Reduction in the number of tools to be provided to the surgeon creates efficiencies and economies as well as reducing waste and cost in the provision of this health-care service, as described in greater detail below. 
     Following the blazing step  1900 , a planing step  2100  can optionally be performed. The planing step  2100  can improve the shape of the remaining resection surface formed in the resection step  1500 , e.g., the portion of the resection between the anchor recess and the cortical bone forming the outer wall of the humerus H at the resection. The planing step  2100  can remove any high points on the resection surface that might interfere with the placement of the articular body in the humeral anchor, as discussed below. The planing step  2100  incorporates a planer  2104 . The planer  2104  is configured to mate with the blazer  1904  and to be mounted to the driver shaft  1608 . Outwardly extending arms with distally extending teeth can be rotated about the blazer  1904  at the level of or just below the level of the resection formed in the resection step  1500 . Such rotation can bring the remaining periphery of the resection into a more planar form without high points that could obstruct the connection of an articular body to the anchor. 
       FIG.  13    shows that after the humerus H has been prepared, the method can continue with a trial step  2150 . The trial step  2150  can employ a trial anchor  2154  which can be placed using the stem impactor-inserter  1908 , as discussed above. The trial anchor  2154  can have more easily disengaged connections with a trial head assembly  2158  (for an anatomical reconstruction) or a trial insert assembly  2162  (for a reverse construction) than would be the case in a final implant. The trial step  2150  can enable a surgeon to choose or confirm a size to be used in the final implant. To the extent an implant can be adjusted by an eccentric coupler or connection feature, the trial step  2150  can allow the surgeon to find the proper level of eccentricity. An eccentric coupler  168  can be used to center the center of rotation of the resection or to provide an eccentric position therefrom. The level of eccentricity can be noted with reference to indicia formed on a proximal surface of the anchor (whether the humeral stem  1200  or the stemless anchor  103 ,  203 ,  303 ,  503 ). Once the final implant size, configuration, and/or orientation have been confirmed the method can proceed to the implantation of the final implant. 
       FIG.  14    shows the stem impactor-inserter  1908  coupled with the stemless anchor  103 . As noted in the figure the stem impactor-inserter  1908  can be coupled with any of the other stemless anchors  203 ,  303 ,  503 . Further the stem impactor-inserter  1908  can be coupled with the humeral stem  1200  as indicated by the surgeon. For example, the use of the common instrumentation enables the surgeon to determine during the procedure that the stemless anchor  103  is not appropriate and then to quickly switch to the humeral stem  1200  following any additional preparation of the humerus H that would make the humerus ready for the humeral stem  1200 . 
     In the case of the stemless anchor  103 , the stem impactor-inserter  1908  can grip the anchor in the recess thereof by engaging the tooling interfaces, e.g., the blind holes  245 . Thereafter, the anchor  103  can be moved into the recess formed in the humerus H and pressed against the prepared surface. Thereafter, an impactor, e.g., a mallet, can be used to apply a load to the impaction head at the proximal end of the stem impactor-inserter  1908  and along the longitudinal axis thereof. The load can thus be directed transverse to, e.g., generally perpendicular to the plane of the resection surface that is formed in the resection step  1500 . 
     In the case of the humeral stem  1200 , the stem impactor-inserter  1908  can grip the anchor in the recess thereof by engaging the tooling interface  1213 , which can comprise these same configuration blind holes as are found in the stemless anchor  103 . The distal end  1218  of the humeral stem  1200  can be inserted through the formed recess in the resection surface and further inserted into the intramedullary canal. Once the diaphysis portion  1204  is in the diaphysis of the humerus H and the metaphysis portion  1202  is in the metaphysis of the humerus, an impaction load can be applied to the stem impactor-inserter  1908 . In particular, an impactor, e.g., a mallet, can strike the impaction head that is disposed adjacent to the distal end of the stem impactor-inserter  1908  driving the humeral stem  1200  into firm engagement with the humerus H generally along the axis of the diaphysis portion  1204  of the humeral stem  1200 . 
     Thus the inserting step  2180  can be achieved for a stemless implant such as the anchor  103  and for a stemmed implant such as the humeral stem  1200  using a same impactor instrument, e.g., the stem impactor-inserter  1908 . 
       FIG.  15    shows an impacting step  2200  that follows the inserting step  2180 . The impacting step  2200  involves impacting an anatomic assembly into the stemless anchor  103  (or another stemless anchor  203 ,  303 ,  503 ). As discussed above, the kit  100  includes shared implant components. As such, the impacting step  2200  can be the same for the humeral stem  1200  as for the stemless anchors  103 . The impacting step  2200  can involve placing the coupler  168  adjacent to the anchor  103 . The coupler  168  can be a centered coupler or an eccentric coupler. An eccentric coupler can have a feature that provides a visual cue as to rotational position of the coupler  168  relative to the anchor  103 . To the extent the trial step  2150  indicated a preferred eccentric rotational position the same position can be re-created in the impacting step  2200 . In particular, the visual cues can be used to rotationally position the coupler  168  and determined in the trial step  2150 . The anatomic articular body  164  can then be placed on the coupler  168  and the anatomic articular body  164  and the coupler  168  can be impacted together onto the anchor  103 . The same steps can be performed with the humeral stem  1200 , aligning the coupler  168  with indicial on a proximal face of the humeral stem  1200 . An impacting load can be applied by a mallet or other tool to the head impactor  2204 . 
       FIG.  16    shows an impacting step  2250  that is similar to the impacting step  2200  except the impacting step  2250  is being used for a reverse articular body  180 . The reverse articular body  180  can be aligned with the stemless anchor  103  (or in a modified example with the humeral stem  1200 ). In some cases, the reverse articular body  180  can be asymmetric such that rotating the reverse articular body  180  can result in a change in the location of the center of the articular surface of the reverse articular body  180 . If the trial step  2150  indicated that a specific rotational position is desired for the reverse articular body  180 , then the surgeon will rotate the reverse articular body  180  to that position before applying an impaction load to the reverse insert impactor  2254 . The reverse insert impactor  2254  can be identical to the head impactor  2204  other than a distal surface of the reverse insert impactor  2254  has a convex shape and the distal end of the head impactor  2204  has a concave shape. 
     Although a typical patient can benefit from the methods described in connection with  FIGS.  7 - 16   ,  FIGS.  17 - 20    illustrate techniques for other patients.  FIGS.  17 - 18    show one approach to a patient with harder than normal bone matter. The method can follow the resection step  1500  and sizing step  1572  with a drilling step  2300 . The drilling step  2300  can benefit from the placement of the guide pin  1580 . A drill head  2304  can be advanced over the guide pin  1580 . The drill head  2304  can have a smaller and more rigid profile than the reaming head  1604 . The drill head  2304  can form a starter hole  2308  in the cancellous bone distal of the resection formed in the resection step  1500 . The starter hole  2308  can be centered on the guide pin  1580  and can have a volume that is less than the final volume to be prepared, e.g., about 10-25 percent of the volume to be ultimately prepared. Following the preparation of the starter hole  2308 , a larger hole closer to the final size can be formed in a progressive reaming step  2350 . The progressive reaming step  2350  can employ an initial reamer  2354  that has a reaming head that is smaller than the reaming head  1604 . The initial reamer  2354  can be more rigid than the reaming head  1604  due to its smaller size. Also, the resistance of the bone can be less if the initial reamer  2354  is tasked with removing less bone volume than the reaming head  1604 . The progressive reaming step  2350  can employ multiple intermediate reamers that are sized between the size of the initial reamer  2354  and the reaming head  1604  to gradually increase the size of the recess distal to the resection until the recess is properly sized for the steps following the reaming step  1600  in the process flow above. 
       FIGS.  19 - 20    shows an example of treating a patient with softer than normal bone. In a collar reaming step  2400  a surgeon can form an annular channel  2412  in the resected humerus H. The annular channel  2412  can be in the location and in the size of the outermost reamed area that would be formed in the reaming step  1600 . The surface formed in the collar reaming step  2400  is generally configured to mate with the bone compression surface  1250  or with the collar of the stemless anchors  103 ,  203 ,  303 ,  503 . A collar reamer  2404  can be provided to form the annular channel  2412 . The collar reamer  2404  can be similar to the reaming head  1604  but can omit the inner and distal cutting features, while retaining the annular reaming teeth  2408 . As a result, the collar reamer  2404  leaves an area of the resection surface located radially inward of the annular channel  2412  generally unaffected or unreamed. After the annular channel  2412  has been prepared a compacting step  2420  can be performed. The compacting step  2420  can be similar to the blazing step  1900  in that the process involves an axial pressing of a compactor  2422  into the cancellous bone inward of the annular channel  2412 . The compactor  2422  can include a depth stop  2424  configured to abut the annular channel  2412  when the compactor  2422  is fully inserted. The depth stop  2424  can include tabs or flanges at opposite sides of the periphery of the proximal end of the compactor  2422 . The depth stop  2424  can extend entirely around the periphery of the proximal end of the compactor  2422  in some examples. The compactor  2422  can have a compacting profile  2428  projecting distally of the depth stop  2424  to a distal end of the compactor  2422 . The compacting profile  2428  can create a compacted recess close in volume to the recess resulting from the reaming step  1600 , e.g., slightly smaller than the blazer  1904  to allow the blazing step  1900  to complete the forming of the recess for receiving the trial anchor  2154  in the process flow above. In another example, the compacting profile  2428  is generally the same as the profile of the blazer  1904  such that the compacting step  2420  can be considered to combine the preparation of the inner area accomplished by the resection step  1500  with the blazing step  1900  into a single step of compacting. The soft bone patient method can continue with the trial step  2150  and the rest of the steps set forth above. 
     B. Dual Use Surgical Instruments 
     As discussed above, one advantage of various kits and systems disclosed herein is that multiple different types of humeral anchors can be implanted using shared instrumentation. Examples of shared instrumentation are discussed below. 
     1. Stem and Stemless Impactor-Inserter 
     As discussed above, a bone anchor, stemmed and/or stemless, may include one or more interfacing features, such as blind holes, configured to engage a tool and enable insertion of the bone anchor (e.g., stemless or stemmed humeral anchor) into the bone.  FIGS.  11 A- 11 D  illustrate an inserter  2500  configured to position a bone anchor, stemmed and/or stemless, into the bone. As discussed in more detail below, the inserter  2500  is configured to receive impaction forces, for example from a mallet, to properly insert the bone anchor into the bone. The proximal surface of the bone anchor takes most of the impaction force via direct contact with a distal surface  2503  of inserter  2500 . 
     The inserter  2500  may include an elongate body  2505 . The elongate body  2505  may generally extend from a first or proximal end  2502  of the inserter  2500  to a second or distal end  2504  of the inserter  2500 . The elongate body  2505  may include an interfacing feature  2514  at the second end  2504  of the inserter  2500 . The interfacing feature  2514  may be configured engage the inserter interface of a bone anchor. For example, the interfacing feature  2514  may be a stationary peg that is fixed with respect to the remainder of the inserter  2500  and does not move (see  FIG.  11 B ). 
     The inserter  2500  may also include a moveable assembly  2506  (see  FIG.  11 D ) coupled with the elongate body  2505 . The moveable assembly  2506  may include a handle  2508  disposed between the first end  2502  and the second end  2504  of the inserter  2500 . The handle  2508  may be coupled, for example pivotably coupled, with the elongate body  2505  at pivot location  2518 . 
     As shown in  FIG.  11 D , the moveable assembly  2506  may also include a bone anchor interface  2510  disposed at the second end  2504  of the inserter  2500 . The bone anchor interface  2510  may be coupled, for example pivotably coupled, with the elongate body  2505  at pivot location  2519 . The bone anchor interface  2510  may include an interfacing feature  2512  configured to engage the inserter interface of a bone anchor. For example, the interfacing feature  2512  may be a peg configured to interface with a blind hole on the bone anchor. The converging angle of the interfacing feature  2512  with respect to the interfacing feature  2514  draws the bone anchor against the distal surface  2503  of the inserter  2500 , which also serves to better distribute impaction forces across a larger surface area of the proximal surface of the bone anchor. 
     The handle  2508  may be directly or indirectly coupled to the bone anchor interface  2510 . For example, the handle  2508  may be indirectly coupled to the bone anchor interface  2510  by a spring linkage  2516 . The spring linkage  2516  may have an arcuate portion and a spring gap  2520 . The spring linkage  2516  may be indirectly coupled to the elongate body  2505  by the handle  2508  and/or the bone anchor interface  2510  without a direct connection between the spring linkage  2516  and the elongate body  2505 . 
     The handle  2508  is configured to move the bone anchor interface  2510  between a first configuration and a second configuration. A proximal end of the handle  2508  is free to move relative to the elongate body  2505 . The transition between the first configuration and the second configuration may include rotation and/or translation of the interfacing feature  2512  with respect to elongate body  2505 . For example, actuating (e.g., pivoting) the handle  2508  toward the elongate body  2505  may move the bone anchor interface  2510  from the first configuration to the second configuration, while releasing the handle  2508  may move the bone anchor interface  2510  back to the first configuration. In the second configuration, the interfacing feature  2512  is rotated and at least partially retracted with respect to a distal surface  2503  of the inserter  2500 . In this position, the surgeon may engage the inserter interface of the bone anchor. While the interfacing feature  2512  engages the inserter interface of the bone anchor, the handle  2508  may be released (e.g., away from the elongate body  2505 ) so as to apply a gripping force to the bone anchor. In the first configuration, the spring linkage  2516  has been compressed (e.g. the spring gap  2520  has been slightly closed), and provides a spring force which helps to hold the interfacing feature  2512  closed against the bone anchor. 
     Inserter  2500  may include at least one impaction head  2522 ,  2524  configured to receive impaction forces from, for example, a mallet. For example, the inserter  2500  may include a first impaction head  2522  and a second impaction head  2524 . The first impaction head  2522  and the second impaction head  2524  may be disposed at different longitudinal positions along the elongate body  2505 . For example, the second impaction head  2524  may be disposed at the first end  2502  of the inserter  2500 , while the first impaction head  2522  may be positioned closer to the second end  2504  of the inserter  2500 . 
     The first impaction head  2522  may be coupled with the elongate body  2505  and disposed at a first angle relative to the longitudinal axis of the elongate body  2505 . When a force is applied to the first impaction head  2522 , the impacting force is directed to the stemmed and/or stemless bone anchor in a direction aligned with a longitudinal axis of the bone anchor to embed the bone anchor in the bone. The second impaction head  2524  may be coupled with the elongate body  2505  and disposed at a second angle, different than the first angle, relative to the longitudinal axis of the elongate body  2505 . When a force is applied to the second impaction head  2524 , the impacting force is directed to the stemmed and/or stemless bone anchor in a direction perpendicular to a resection plane of the bone in which the bone anchor will be embedded. For example, the first impaction head  2522  may be used to insert a stemmed bone anchor and the second impaction head  2524  may be used to insert a stemless bone anchor. In another example, both the first impaction head  2522  and the second impaction head  2524  may be used to embed a stem portion in the bone. As another example, the inserter  2500  may only include the first impaction head  2522 . 
     The first impaction head  2522  may be disposed at an angle relative to the second impaction head  2524  and/or the longitudinal axis L of the elongate body  2505 . The first impaction head  2522  may be disposed at an acute angle relative to the second impaction head  2524 , for example between about 35 degrees and about 65 degrees to accommodate stemmed bone anchors having an inclination angle between 125 degrees and about 155 degrees. In one example, the first impaction head  2522  may be disposed at a 45 degree angle relative to the second impaction head  2524 . 
     The inserter  2500  may also be configured to receive a retroversion rod. For example, the retroversion rod may be inserted into one of the openings  2526 . Each opening may position the retroversion rod at a different angle, corresponding to the desired angle of resection, and allow the surgeon to evaluate the version. If the proximal bone resection was not accurate or for other reasons dictated by surgeon judgment, the surgeon can modify the resection plane. 
     The inserter  2500  may form part of a kit including a stemless bone anchor and/or a stemmed bone anchor. The stemless and/or stemmed bone anchor may include any of the features of the implants described above. The bone anchor interface  2510  may be configured to engage the inserter interface of the stemless bone anchor and/or the inserter interface of the stemmed bone anchor. 
     The kit may include a first inserter and a second inserter. Each of the first inserter and the second inserter may include any of the features described above with respect to the inserter  2500 . In the first inserter, the first impaction head and the second impaction head may be disposed at a first angle relative to each other. In the second inserter, the first impaction head and the second impaction head may be disposed at a second angle relative to each other. The second angle may be different from the first angle. One of the first inserter and the second inserter may be selected based on the angle at which the resection is formed in the bone. 
     In use, the same inserter  2500  may engage the inserter interface of a first, stemless bone anchor or the inserter interface of a second, stemmed bone anchor. The stemless and/or stemmed bone anchor may include any of the features of the implants described above. For example, the inserter  2500  may engage the inserter interface of the stemless bone anchor and advance the stemless bone anchor into bone matter exposed at a resection of a bone. When advancing the stemless bone anchor, a force may be applied to the second impaction head  2524  of the inserter  2500  to apply a force perpendicular to the resection plane of the bone. 
     The same inserter  2500  may engage the inserter interface of the stemmed bone anchor and advance the stemmed bone anchor to position the stem of the bone anchor in a medullary canal of the bone. When advancing the stemmed bone anchor, a force may be applied to the first impaction head  2522  of the inserter  2500  to apply a force aligned with a longitudinal axis of the stemmed bone anchor to embed the stem in the bone. 
     2. Reamer for Preparation of Humerus for Stem and Stemless Anchors 
     As discussed above, the kit  100  can include stemless humeral anchors and humeral anchors with stems. Proximal or metaphyseal portions of these anchors can have the same or similar structures. For example, the proximal end  239  of the humeral anchor  203  can have an overhanging surface opposite the proximal face of the anchor. The overhanging surface can rest on resected bone, e.g., on cancellous bone of the humerus. Similarly, the bone compression surface  1250  of the humeral anchor  1200  can be provided to overhang the same bone surface or portion. The shared design concepts can advantageously use a shared reamer or a collection of reamers having at least one shared design feature. 
     As noted above, the reamer head  1800  can have an outer periphery with a distal facing cutting edge configured to form the recessed surface R. The recessed surface R can be formed inward of the cortical wall, as discussed above. The recessed surface R can be configured to receive the overhanging surface of the anchor  203  or the anchor  1200  or another one of the anchors disclosed herein. Additional features of the reamer  1800  and a reamer including the reamer hea 1850 A are discussed above. 
     Other reamers that can be used for either stem or stemless humeral anchor preparation are also described herein. For example, the initial reamer  2354  can be used in a progressive reaming method for either stem or stemless preparation. The reamer  2354  can be succeeded by larger reamers and/or by tools for accessing and preparing a humeral intramedullary canal. The reamer  2354  can form the recessed surface R. Also, the collar reamer  2404  can be used to prepare a humerus with soft bone for either a stemless or a stemmed anchor. The collar reamer  2404  can prepare the recessed surface, which can come before providing access to the intramedullary canal through relatively soft bone. 
     Because the kit  100  includes reamers and other instruments that can be used with more than one type of humeral anchor, e.g., with a stemmed and a stemless anchor, the kit is less complex and also less costly than a kit requiring specialized reamers and instruments for each of the stemmed and stemless anchors. Also, given that tools are sometimes discarded after a surgery rather than reused, this approach reduces waste and inefficiencies in the provision of the surgery to the patient. This provides multiple advantages given the cost of such procedures. 
     Terminology 
     Although certain embodiments have been described herein, the implants and methods described herein can interchangeably use any articular component, as the context may dictate. 
     As used herein, the relative terms “proximal” and “distal” shall be defined from the perspective of the implant. Thus, proximal refers to the direction of the articular component and distal refers to the direction of an anchor component, such as a stem of a humeral anchor or a thread or porous surface or other anchoring structure of a stemless anchor when the implant is assembled. 
     Conditional language, such as “can,” “could,” “might,” or “may,” unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements, and/or steps. Thus, such conditional language is not generally intended to imply that features, elements, and/or steps are in any way required for one or more embodiments. 
     The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. In addition, the articles “a,” “an,” and “the” as used in this application and the appended claims are to be construed to mean “one or more” or “at least one” unless specified otherwise. 
     The ranges disclosed herein also encompass any and all overlap, sub-ranges, and combinations thereof. Language such as “up to,” “at least,” “greater than,” “less than,” “between,” and the like includes the number recited. Numbers preceded by a term such as “about” or “approximately” include the recited numbers and should be interpreted based on the circumstances (e.g., as accurate as reasonably possible under the circumstances, for example ±5%, ±10%, ±15%, etc.). For example, “about 1” includes “1.” Phrases preceded by a term such as “substantially,” “generally,” and the like include the recited phrase and should be interpreted based on the circumstances (e.g., as much as reasonably possible under the circumstances). For example, “substantially spherical” includes “spherical.” Unless stated otherwise, all measurements are at standard conditions including temperature and pressure. 
     As used herein, a phrase referring to “at least one of” a list of items refers to any combination of those items, including single members. As an example, “at least one of: A, B, or C” is intended to cover: A, B, C, A and B, A and C, B and C, and A, B, and C. Conjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is otherwise understood with the context as used in general to convey that an item, term, etc. may be at least one of X, Y or Z. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y and at least one of Z to each be present. 
     Although certain embodiments and examples have been described herein, it should be emphasized that many variations and modifications may be made to the humeral head assembly shown and described in the present disclosure, the elements of which are to be understood as being differently combined and/or modified to form still further embodiments or acceptable examples. All such modifications and variations are intended to be included herein within the scope of this disclosure. A wide variety of designs and approaches are possible. No feature, structure, or step disclosed herein is essential or indispensable. 
     Some embodiments have been described in connection with the accompanying drawings. However, it should be understood that the figures are not drawn to scale. Distances, angles, etc. are merely illustrative and do not necessarily bear an exact relationship to actual dimensions and layout of the devices illustrated. Components can be added, removed, and/or rearranged. Further, the disclosure herein of any particular feature, aspect, method, property, characteristic, quality, attribute, element, or the like in connection with various embodiments can be used in all other embodiments set forth herein. Additionally, it will be recognized that any methods described herein may be practiced using any device suitable for performing the recited steps. 
     For purposes of this disclosure, certain aspects, advantages, and novel features are described herein. It is to be understood that not necessarily all such advantages may be achieved in accordance with any particular embodiment. Thus, for example, those skilled in the art will recognize that the disclosure may be embodied or carried out in a manner that achieves one advantage or a group of advantages as taught herein without necessarily achieving other advantages as may be taught or suggested herein. 
     Moreover, while illustrative embodiments have been described herein, it will be understood by those skilled in the art that the scope of the inventions extends beyond the specifically disclosed embodiments to any and all embodiments having equivalent elements, modifications, omissions, combinations or sub-combinations of the specific features and aspects of the embodiments (e.g., of aspects across various embodiments), adaptations and/or alterations, and uses of the inventions as would be appreciated by those in the art based on the present disclosure. The limitations in the claims are to be interpreted broadly based on the language employed in the claims and not limited to the examples described in the present specification or during the prosecution of the application, which examples are to be construed as non-exclusive. Further, the actions of the disclosed processes and methods may be modified in any manner, including by reordering actions and/or inserting additional actions and/or deleting actions. It is intended, therefore, that the specification and examples be considered as illustrative only, with a true scope and spirit being indicated by the claims and their full scope of equivalents. 
     Any methods disclosed herein need not be performed in the order recited. The methods disclosed herein include certain actions taken by a practitioner; however, they can also include any third-party instruction of those actions, either expressly or by implication. For example, actions such as “coupling a glenoid guide with the glenoid rim” include “instructing coupling of a glenoid guide with a glenoid rim.”