Patent Description:
In cases of severe glenoid wear, it can be difficult to return the joint to near neutral version using a standard implant. In these instances, the surgeon has to compromise by putting in the component at a non-ideal version angel, removing significant amount of native bone to gain complete backside coverage of the glenoid base, or bone grafting to support the backside of the glenoid implant.

Recently, glenoid implants with augments have been developed as options for these cases with severe glenoid wear. For anatomic shoulder arthroplasty, augmented glenoid implants can include various stepped or contoured bone-contacting surfaces. However, many of these designs still require removal of a significant amount of bone.

Examples of glenoid implants are described in <CIT> et al. , <CIT>et al. , <CIT>et al. , and <CIT>et al.

Document <CIT> discloses an exemplary ream guide.

The present inventors have recognized, among other things, that a problem to be solved can include the need to reduce the amount of bone removed when implanting glenoid implants. Furthermore, the present inventors have recognized that another problem to be solved can include the need to simplify bone preparation techniques when installing glenoid implants.

The present subject matter can help provide a solution to this problem, such as by providing augmented implants with angled, sloped and partially sloped bone-contacting surfaces, and instruments and guides for implanting such augmented implants, in patient-specific and non-patient specific embodiments. Only ream guides according to claim <NUM> are protected by the appended claims.

A glenoid implant can comprise a body comprising: an articular surface configured to mate with or receive another component configured to mate with a complimentary component; and a scapula-engaging surface opposite the articular surface, the scapula engaging surface including first and second portions angled relative to each other; and a fixation feature extending from the scapula-engaging surface.

A method for implanting a scapular baseplate in a shoulder arthroplasty is described herein although it does not fall within the scope of the claims. Said method can comprise: inserting a guide pin into a glenoid of the scapula using a guide instrument; preparing a first portion of the glenoid to form a planar bone surface using the guide pin; forming a first bore into the glenoid located approximately at the guide pin; forming a second bore into the glenoid offset from the first bore; inserting an augment ream guide into the first bore and the second bore; and preparing a second portion of the glenoid to form an angled bone surface relative to the planar bone surface using the augment ream guide.

A ream guide for a shoulder arthroplasty procedure can comprise: a base having a first surface and a second surface; a bone peg extending perpendicularly from the first surface; an alignment peg extending from the first surface spaced from the bone peg; and a guide peg extending from the second surface opposite the bone peg at an oblique angle to the bone peg.

The following figures show different examples of guides, implants and instruments. Only the guide of <FIG> fall within the scope of the invention as claimed.

<FIG> is a cross-sectional view of prior art anatomic shoulder implant <NUM> comprising implanted glenoid implant <NUM> and implanted humeral implant <NUM>. Glenoid implant <NUM> can include glenoid <NUM> and humeral implant <NUM> can include humeral head <NUM>. Glenoid implant <NUM> can be secured to glenoid G of scapula S using center post <NUM> and peripheral post <NUM>. Humeral implant <NUM> can be secured to humerus H using any suitable means, such as center post <NUM> and fasteners 26A and 26B. Glenoid G of scapula S can typically be reamed to provide a single surface to engage bone surface <NUM> of glenoid implant <NUM>. As can be seen, glenoid implant <NUM> can be typically of substantially uniform thickness and bone surface <NUM> typically can comprise a single smooth surface, other than the portions associated with center post <NUM> and peripheral post <NUM>. These geometric features of glenoid implant <NUM> can sometimes unavoidably result in some amount of healthy bone being removed.

<FIG> is a cross-sectional view of prior art reverse shoulder implant <NUM> comprising implanted humeral tray <NUM> and implanted glenosphere baseplate <NUM>. Humeral tray <NUM> can include polyethylene (PE) liner <NUM> and glenosphere baseplate <NUM> can include glenosphere <NUM>. Humeral tray <NUM> can be secured to humerus H using any suitable means, such as center post <NUM> and stem <NUM>. Glenosphere baseplate <NUM> can be secured to glenoid G of scapula S using center post <NUM> and fasteners 46A - 46C. Baseplate <NUM> can be secured by other means, such as through the use of four peripheral screws and a center post. Glenoid G of scapula S can typically be reamed to provide a single surface to engage bone surface <NUM> of glenosphere baseplate <NUM>. As can be seen, glenosphere baseplate <NUM> can be typically of substantially uniform thickness and bone surface <NUM> typically can comprise a single smooth surface, other than the portions associated with center post <NUM> and fasteners 46A - 46C. These geometric features of glenosphere baseplate <NUM> can sometimes unavoidably result in some amount of healthy bone being removed.

<FIG> is a perspective view of reverse shoulder implant <NUM> including augmented baseplate <NUM> having angled bone surface <NUM>. Baseplate <NUM> can also include stem <NUM>, mate face <NUM> and bores 58A - 58E (56D shown in <FIG>) for receiving fixation fasteners 60A - 60E. Angled bone surface <NUM> can include parallel surface 54A and oblique surface 54B. Implant <NUM> can also include glenosphere <NUM>, which can include stem <NUM>. Parallel surface 54A can be parallel to mate face <NUM>, as well as distal surface <NUM> of stem <NUM>. In various embodiments, baseplate <NUM> can be made of a porous material, such as a highly porous metal, Trabecular Metal ®, or tantalum.

<FIG> is a perspective view of the augmented baseplate <NUM> of <FIG> implanted on scapula S. Glenoid G of scapula S can be prepared to mate with parallel surface 54A and oblique surface 54B, such as by reaming of glenoid G to form obliquely oriented planar bone surfaces. Oblique surface 54B can be located in any orientation of glenoid G. For example, oblique surface 54B can be located at superior, inferior, posterior or anterior portions on glenoid G, or at any intermediate orientation. The methods, instruments and tools described herein, particularly with reference to <FIG>, facilitate implantation of augmented baseplate <NUM> onto scapula S in such a manner so as to minimize bone removal and subsequently align augmented baseplate so that surfaces 54A and 54B mate flush with prepared surfaces of glenoid G.

<FIG> is a perspective view of standard (i.e. non-patient-specific) glenoid guide instrument <NUM> being used to insert guide pin <NUM> into glenoid G of scapula S. Instrument <NUM> can include pin placement guide <NUM> and glenoid guide handle <NUM>.

The appropriate pin placement guide <NUM> can be selected based on the degree of glenoid erosion. For example, oblique surface 54B of augmented baseplate <NUM> (<FIG>) can be angled relative to parallel surface 54A at an angle of <NUM>°, <NUM>° or <NUM>°. Thus, pin placement guide <NUM> can be made to substantially align guide pin <NUM> with to the central axis of the vault of glenoid G for <NUM>°, <NUM>°, or <NUM>° baseplates. However a <NUM> degree inferior tilt can be built into placement guide <NUM>. The appropriate pin placement guide <NUM> is selected to align guide pin <NUM>, which can be a Steinman pin, in the desired version and inclination. Glenoid guide handle <NUM> can be attached to the appropriate augment pin placement guide <NUM> (<NUM>°, <NUM>°, or <NUM>°). In one example, a <NUM> Steinmann pin is used as guide pin <NUM> and is inserted into glenoid G at the desired angle and position, ensuring pin <NUM> engages or perforates the medial cortical wall. A completely secure guide pin is desired to ensure the subsequent used reamer has a stable cannula over which to ream.

When guide pin <NUM> is placed correctly within guide <NUM>, guide pin <NUM> can lie flush with inferior groove <NUM>. Pin placement guide <NUM> can be centered over the inferior portion of glenoid G. However, in glenoid deformity cases and situations with poor bone quality, guide pin <NUM> can be placed into the best possible bone stock.

<FIG> is a perspective view of patient-specific glenoid guide instrument <NUM> being used to insert guide pin <NUM> into glenoid G of scapula S. Patient-specific glenoid guide instrument <NUM> can include base <NUM>, anatomic guide sleeve <NUM> and reverse guide sleeve <NUM>. Base <NUM> can include patient-specific bone surface <NUM>. At least a portion of the scapula-engaging bone surface <NUM> is configured to mirror and conform to a surface of scapula S of a specific patient based on a three-dimensional (3D) model of scapula S. In one embodiment, patient-specific glenoid guide instrument <NUM> can comprise a Signature guide tool commercially available from Zimmer Biomet. One or more examples of a Signature guide tool are described in <CIT>et al.

<FIG> is a perspective view of face reamer <NUM> being advanced along guide pin <NUM> of <FIG> to partially ream glenoid G of scapula S. Face reamer <NUM> includes cannulated shaft <NUM> and reamer head <NUM>.

First, the non-deficient half or portion of the native surfaces of glenoid G can be prepared, before the deficient, or damaged half of portion of the surfaces of glenoid G are prepared. Cannulated shaft <NUM> of face reamer <NUM> can be positioned over guide pion <NUM> and rotated to remove bone from glenoid G. In one example, bone can be reamed on at least <NUM> percent of the face of glenoid G. Due to the <NUM> degree inferior tilt of guide pin <NUM>, inferior ridge R may be evident with bone also prepared opposite of the glenoid erosion.

<FIG> is a close up view of partially reamed scapula S of <FIG> with guide pin <NUM> inserted therein. After face reamer <NUM> is removed, guide pin <NUM> remains seated within glenoid G. Face reamer <NUM> can produce central bore <NUM> and first reamed surface <NUM>. Central bore <NUM> can be centered around guide pin <NUM> and first reamed surface <NUM> can include edge E that extends across central bore <NUM> at the level of guide pin <NUM>.

<FIG> is a perspective view of augment sizer <NUM> being advanced along guide pin <NUM> of <FIG> to measure the size of partially reamed scapula S. <FIG> is a side cross-sectional view of augment sizer <NUM> of <FIG> correctly seated with properly reamed glenoid G. Augment sizer <NUM> can include shaft <NUM>, finger <NUM> and base <NUM>, and can come in different sizes (<NUM>°, <NUM>° and/or <NUM>°) for the different sized baseplates <NUM>.

It is desirable that glenoid G be reamed to at least fifty percent to ensure glenoid G is prepared to fully support parallel face 54A of augment baseplate <NUM>. Reaming beyond fifty percent can remove additional bone which is not necessary for augment preparation. As discussed below, in one example, using augment sizer <NUM> before reaming, a line can be drawn at the fifty percent line on the face of glenoid G (which can coincide with edge E), such as with a blue marker or bovie, and reaming is performed until the line disappears to ensure glenoid G is reamed to the desired precision level.

Augment sizer <NUM> can be used to measure and ensure at least fifty percent of the face of glenoid G has been reamed. After fifty percent of the face of glenoid G is reamed, a central channel of shaft <NUM> can be slid onto guide pin <NUM> until finger <NUM> engages the partially reamed scapula S.

After the glenoid face has been reamed at least <NUM> percent, the different sized augment sizers <NUM> (<NUM>°, <NUM>° and/or <NUM>°) can be used to determine which size augment baseplate <NUM>. First the <NUM>° augment sizer can be placed on the fifty percent reamed glenoid G. First, it can be evaluate whether or not the <NUM>° finger <NUM> touches the non-reamed (defect) portion of the face of glenoid G or sits proud. If the <NUM>° augment sizer finger <NUM> sits proud, off the face of the defect, then glenoid G can be re-evaluated with the <NUM>° augment sizer. If the <NUM>° augment sizer finger <NUM> touches the defect yet sits proud, off the face of the fifty percent reamed surface, this is the size of augmented baseplate <NUM> that can or should be chosen. This algorithm can be continued until the optimal augment is found. There may be circumstances where the defect is in between sizes, and the surgeon can make a judgment call as to either go to a taller augment, reaming the defect side, or to go to a shorter augment, reaming the high side of glenoid G. Once fifty percent of the face of glenoid G is reamed, face reamer <NUM> can be removed from guide pin <NUM>.

As mentioned, augment sizer <NUM> can also be used to determine which size (<NUM>°, <NUM>° or <NUM>°) augmented baseplate <NUM> should be used before scapula is reamed. Augment sizer <NUM> can come in three sizes (<NUM>°, <NUM>° or <NUM>°) to correspond the differently sized augmented baseplates <NUM>. Augment sizer <NUM> can be positioned over guide pin <NUM> to engage the face of glenoid G. Augment sizer <NUM> can be dialed (e.g. rotated on guide pin <NUM>) to position finger <NUM> in the appropriated direction to allow the maximum defect to be removed and augmented baseplate <NUM> will lie in the desired orientation. The correctly sized augment sizer will have both finger <NUM> and base <NUM> engage glenoid G. As mentioned, a bovie or surgical marker can be used to mark the fifty percent line on the face of glenoid G, as this will be used in the subsequent step to determine sufficient ream depth, just described.

<FIG> is a perspective view of alignment peg drill guide <NUM> being advanced along guide pin <NUM> of <FIG> in order to drill an alignment hole in the partially reamed scapula using drill bit <NUM>. Alignment peg drill guide <NUM> can comprise handle shaft <NUM>, baseplate <NUM>, half-circle etch <NUM>, windows <NUM> and guide hole <NUM>. <FIG> is a close up view of the partially reamed scapula S of <FIG> including alignment hole <NUM> produced using drill guide <NUM> of <FIG>.

Base plate <NUM> can be positioned on glenoid G with the half-circle etch <NUM> in the exact location where the augment is desired. In one example, at least a portion of the scapula-engaging surface of base plate <NUM> can be configured to mirror and conform to a surface of scapula S of a specific patient based on a three-dimensional (3D) model of scapula S. Windows <NUM> can be referenced and centered on edge E of the fifty percent reamed glenoid. Once properly oriented, drill bit <NUM> can be inserted into guide hole <NUM> in baseplate <NUM> and glenoid G can be drilled to form a hole for receiving an alignment finger of an inserter (discussed below). In one example, guide hole <NUM> and drill bit <NUM> can be sized to produce a <NUM> hole. Drill bit <NUM> can be advanced until the drill depth is achieved by a shoulder on drill bit <NUM> bottoming out on baseplate <NUM>. In other embodiments, an etch can be provided on drill bet <NUM> to indicate the desired drill depth. Drilling of a <NUM> alignment hole can help facilitate orientation of augmented baseplate <NUM> during insertion. Drill guide <NUM> can then be removed from guide pin <NUM> and guide pin <NUM> can be removed from glenoid G.

<FIG> is an exploded view of augment ream guide <NUM>, fixation fastener <NUM> and driver instrument <NUM>. <FIG> is a perspective view of augment ream guide <NUM> seated on partially reamed scapula S with driver instrument <NUM> inserted into augment ream guide <NUM>. <FIG> is a side view of augment ream guide <NUM>, which can include bone peg <NUM>, guide peg <NUM>, base <NUM> and alignment post <NUM>. Glenoid G can include alignment hole <NUM> produced by drill bit <NUM> in the previous step.

Bone peg <NUM> can extend substantially perpendicularly from the bottom surface of base <NUM>, while guide peg <NUM> can extend at an oblique angle to bone peg <NUM>. Substantially perpendicular can include the central axis of bone peg <NUM> being disposed ninety degrees to the bottom surface of base <NUM>, as well as the central axis being within five degrees of perpendicular. Substantial perpendicularity of bone peg <NUM> can facilitate easy insertion of augment ream guide <NUM> into central bore <NUM>.

Guide pin <NUM> can be removed. The appropriately sized (<NUM>°, <NUM>° of <NUM>°) augment ream guide <NUM> can be placed on the prepared glenoid G taking care to align alignment hole <NUM> with alignment post <NUM> on ream guide <NUM>. Next, bone peg <NUM> can be inserted into central bore <NUM> in glenoid G, and fixation fastener <NUM> can be inserted into guide peg <NUM> until it is fully seated within augment ream guide <NUM>. Fixation fastener <NUM> can be inserted using a hex driver under hand power. Etch line <NUM> on drive instrument <NUM> can align with etch line <NUM> on ream guide <NUM> when completely seated. Fixation fastener <NUM> can be engineered with the same pitch as fixation fastener 60E (<FIG>) to help ensure every thread of fixation fastener 60E will engage undisturbed bone. Fixation fastener <NUM> can provide fixation of ream guide <NUM> during reaming for augmented baseplate <NUM>.

<FIG> is a perspective view of augment reamer <NUM> being advanced along augment ream guide <NUM> (shown in phantom) of <FIG> to further ream the partially reamed scapula S. <FIG> is a close up view of completely reamed scapula S of <FIG> including central bore <NUM>, first reamed surface <NUM>, alignment hole <NUM> and second reamed surface <NUM>.

The appropriately sized (<NUM>°, <NUM>° or <NUM>°) augment reamer <NUM> can be placed over guide peg <NUM> of augment ream guide <NUM>. Reamer <NUM> can include notch <NUM> that extends into shaft <NUM> head <NUM>. In particular, a portion of the circumference of shaft <NUM> can be cut away at the end of shaft <NUM> that engages head <NUM>, and head <NUM> can include a similarly located notch that extends into the circumference of head <NUM> at the same circumferential location as the cut away portion of shaft <NUM>. The notch in head <NUM> can extend to the center of head <NUM> so that head <NUM> has a U shape. Configured as such, reamer <NUM> can be slipped over guide peg <NUM> without the axes of shaft <NUM> and guide peg <NUM> being coaxial. Thus, reamer <NUM> can be advanced normal to the face of glenoid G. Thus, reamer <NUM> can enter more directly into an incision in the patient and avoid surrounding tissues.

Reamer <NUM> can be fully captured on ream guide peg <NUM> before beginning to ream, such as by contacting reamer head <NUM> against glenoid G. Reamer shaft <NUM> can be rotated to remove bone. If necessary, glenoid osteophytes can be removed to allow proper seating of reamer <NUM>. Reaming can continue to advance reamer head <NUM> until a shoulder within reamer shaft <NUM> bottoms out on ream guide peg <NUM> and the appropriate amount of bone has been prepared to accept the selected size of augmented baseplate <NUM>. Ream guide <NUM> can be designed to allow minimal reaming of the bone necessary to seat augmented baseplate <NUM>. Next, fixation fastener <NUM> (<FIG>) can be removed and augment ream guide <NUM> can also be removed. Glenoid G can subsequently can include second reamed surface <NUM> opposite first reamed surface <NUM>. First and second reamed surfaces <NUM> and <NUM> can adjoin at edge E. Thus, in one example, glenoid G can now accept augmented baseplate <NUM>. In particular, parallel surface 54A can abut first reamed surface <NUM> and oblique surface 54B can abut second reamed surface <NUM>.

<FIG> is an exploded view of augmented baseplate impactor <NUM> and augmented baseplate <NUM>. Augmented baseplate impactor <NUM> can include alignment post <NUM>, which can be used to align augmented baseplate <NUM> with alignment hole <NUM>. <FIG> is a perspective view of impact face <NUM> of augmented baseplate impactor <NUM> showing alignment post <NUM>, center post <NUM> and peripheral post <NUM>.

Augmented baseplate <NUM> can be placed onto impact face <NUM> of baseplate impactor <NUM>. For example, central post <NUM> can be inserted into bore 58E in baseplate <NUM>, while peripheral post <NUM> is inserted into bore 58A. Alignment post <NUM> can extend through bore 58C to be inserted into alignment hole <NUM>. Additionally, proper orientation of impactor <NUM> can determined by aligning the augment of baseplate <NUM> (e.g. oblique surface 54B) with a corresponding "augment" label on inserter <NUM>. When alignment post <NUM> is in the correct orientation, half-circle etch <NUM> on inserter <NUM> can align with second reamed surface <NUM>.

Once aligned, augmented baseplate <NUM> can be impacted into glenoid G and remove augmented baseplate impactor <NUM>. Parallel and oblique surfaces 54A, 54B of augmented baseplate <NUM> can or should be fully seated on first and second reamed surfaces <NUM>, <NUM>, respectively on the face of glenoid G. Fasteners 60A -60E can be used to secure baseplate <NUM> to scapula S, and glenosphere <NUM> can be attached to baseplate <NUM> via stem <NUM>.

Visual confirmation can be attained by checking for gaps between the reamed surface of glenoid G and baseplate <NUM> at bores 58A - 58D. A small nerve hook can be used to aid in confirming complete seating of baseplate <NUM>. Due to the <NUM> degree inferior to superior orientation for the baseplate preparation, baseplate <NUM> may be partially or fully counter-sunk inferiorly. Guide pin <NUM> can be reinserted before impacting baseplate <NUM> if cannulated insertion is desired.

<FIG> is a perspective view of augmented baseplate <NUM> for an anatomic shoulder implant having angled bone surface <NUM> with fixation posts 204A - 204C. Baseplate <NUM> can also include articular surface <NUM>, which can be configured to directly engage a humeral head. Angled bone surface <NUM> can include crenellations or corrugations <NUM> that can be used to engage bone and promote bone growth. Angled bone surface <NUM> can include parallel surface 210A, which can be parallel to glenoid surface <NUM>, and oblique surface 210B, which can be angled at an oblique angle relative to parallel surface 210A.

Glenoid G of scapula S can be prepared to mate with parallel surface 210A and oblique surface 210B, such as by reaming of glenoid G to form obliquely oriented planar bone surfaces. Oblique surface 210B can be located in different orientations on glenoid G, depending on the particular implant and particular patient. The methods, instruments and tools described herein, particularly with reference to <FIG>, facilitate implantation of augmented baseplate <NUM> onto scapula S in such a manner so as to minimize bone removal and subsequently align augmented baseplate so that surfaces 210A and 210B mate flush with prepared surfaces of glenoid G.

<FIG> is a schematic view of patient-specific glenoid guide <NUM> engaging glenoid G of a scapula to install guide pin <NUM> substantially parallel to the central axis of the vault of glenoid G. In the depicted example, glenoid G is classified as a Walch B2 glenoid, e.g., a retroverted glenoid with posterior rim erosion, or a biconcave wear pattern with an alpha angle. Patient-specific glenoid guide <NUM> can be placed onto the face of glenoid G. Guide pin <NUM> can be inserted through glenoid guide <NUM> into the glenoid vault of glenoid G.

<FIG> is a schematic view of depth stop <NUM> installed around guide pin <NUM> of <FIG>. In one example, depth stop <NUM> can be patient-specific in that the length of depth stop <NUM> can be sized to allow a reamer to ream glenoid G to a depth based on a specific patient's bone defects. Depth stop <NUM> can include a central bore <NUM> to receive guide pin <NUM>. The outer diameter of depth stop <NUM> can be sized to receive a socket of a corresponding reamer.

<FIG> is a schematic view of reamer <NUM> installed around guide pin <NUM> and depth stop <NUM> of <FIG>. Reamer <NUM> can be a standard face reamer that includes socket <NUM> for receiving depth stop <NUM>. Reamer <NUM> can be advanced until end wall <NUM> of socket <NUM> engages the proximal surface of depth stop <NUM>. Reamer <NUM> can form first prepared surface <NUM> on glenoid G.

<FIG> is a schematic view of boss and post reamer <NUM> installed around guide pin <NUM> of <FIG>. Post reamer <NUM> can include central portion <NUM>, which can be configured as a reamer, drill or a rasp to remove bone from glenoid G. In particular, central portion <NUM> can be stepped to provide bore <NUM> having various diameters within scapula S. In particular, central portion <NUM> can be stepped to provide progressively smaller diameter bore segments within scapula S the deeper bore <NUM> goes into the bone. Central portion <NUM> can be shaped to mate with the shape of fixation post 204A of augmented baseplate <NUM>.

<FIG> is a schematic view of peripheral post guide <NUM> installed around guide pin <NUM> of <FIG>. Post guide <NUM> includes sockets 232A and 232B for receiving drill or reamer <NUM>, as well as socket <NUM> for receiving guide pin <NUM>. Sockets 232A and 232B are positioned relative to guide pin <NUM> in order to place bores 238A and 238B relative to bore <NUM> in locations to correspond to posts 204A - 204C on baseplate <NUM>. Thus, after post reamer <NUM> is removed from guide pin <NUM>, socket <NUM> of peripheral post guide <NUM> can be slipped around guide pin <NUM> and reamer <NUM> can be used to make bores 238A and 238B using sockets 232A and 232B, respectively. Drill <NUM> can include stop <NUM> to ensure that bores 238A and 238B are reamed to the depth of posts 204B and 204C. Bores 238A and 238B can be shaped to mate with the shape of fixation posts 204B and 204C, respectively.

<FIG> is a schematic view of patient-specific angled ream guide <NUM> installed with compression screw <NUM> that follows the path of the guide pin of <FIG>. Guide pin <NUM> can be removed and angled ream guide <NUM> can be inserted into bore <NUM>. Compression screw <NUM> can be inserted into ream guide <NUM> and threaded into scapula S along the path of guide pin <NUM> to stabilize ream guide <NUM> for reaming. Angled ream guide <NUM> can be configured similarly to ream guide <NUM> of <FIG>. Ream guide <NUM> can include bone post <NUM> that is shaped to at least partially fill bore <NUM> and that includes a central bore for receiving compression screw <NUM>. Guide post <NUM> can extend from bone post <NUM> at angle α, which can correspond to the angle between surfaces 210A and 210B of augmented baseplate <NUM>. Alignment post <NUM> can be connected to ream guide <NUM> to orient guide post <NUM> in the correct direction. Alignment post <NUM> can have the shape of 204C and bone post <NUM> can have the shape of post 204A.

<FIG> is a schematic view of reamer <NUM> installed around guide post <NUM> of angled ream guide <NUM> of <FIG>. Reamer head <NUM> includes socket <NUM> to receive guidepost <NUM>. Using shaft <NUM>, reamer head <NUM> can be rotated to form second prepared surface <NUM> on glenoid G. Guide post <NUM> can act as a depth stop to limit advancement or reamer <NUM>. Reamer <NUM> thereby produces second prepared surface <NUM> at angle α relative to first prepared surface <NUM> so that prepared surfaces <NUM> and <NUM> mate with surfaces 210A and 210B, respectively of baseplate <NUM>.

<FIG> is a perspective view of augmented glenoid implant <NUM> having slanted bone surface <NUM>. Glenoid implant <NUM> can also include surface <NUM>, center post <NUM>, and peripheral posts 310A and 310B. Slanted bone surface <NUM> can form first thickness t1 with surface <NUM> at a first end and second thickness t2 with surface <NUM> at a second end.

Glenoid G of scapula S can be prepared to mate with slanted bone surface <NUM>, such as by partially reaming of glenoid G at an angle to remove damaged bone. Slanted bone surface <NUM> of augmented baseplate <NUM> can then partially mate flush with the surface of glenoid G reamed at an angle and partially mate flush with a naturally angled, undreamed surface of glenoid G. Alternatively, substantially all of glenoid G can be reamed at the desired angle to mate with slanted bone surface <NUM>. The methods, instruments and tools described herein, particularly with reference to <FIG>, facilitate implantation of augmented baseplate <NUM> onto scapula S in such a manner so as to minimize bone removal and subsequently align augmented baseplate <NUM> so that slanted bone surface <NUM> mates flush with the prepared surface of glenoid G.

<FIG> is a schematic view of a patient-specific glenoid guide <NUM> engaging glenoid G of scapula S to install guide pin <NUM> at angle β. In the depicted example, glenoid G is classified as a Walch B1 glenoid, e.g., a glenoid having a narrow posterior joint space, subchondral sclerosis and osteophytes or a sloped wear pattern with a beta angle. Patient-specific glenoid guide <NUM> is placed onto the face of glenoid G. Guide pin <NUM> is inserted through glenoid guide <NUM> into the glenoid vault of glenoid G. Glenoid guide <NUM> mates with glenoid G to align guide pin <NUM> at angle β, which can be the pathologic angle of glenoid G. Angle β can be predetermined from a surgical plan to allow a reamer to engage a high side of glenoid G having bone damage.

<FIG> is a schematic view of depth stop <NUM> surrounding guide pin <NUM> of <FIG>. In one example, depth stop <NUM> can be patient-specific in that the length of depth stop <NUM> can be sized to allow a reamer to ream glenoid G to a depth based on a specific patient's bone defects. Depth stop <NUM> can include central bore <NUM> to receive guide pin <NUM>. The outer diameter of depth stop <NUM> can be sized to receive a socket of a corresponding reamer.

<FIG> is a schematic view of reamer <NUM> being advanced onto guide pin <NUM> of <FIG> to surround depth stop <NUM> and at least partially ream glenoid G. Reamer <NUM> can be a standard face reamer that includes socket <NUM> for receiving depth stop <NUM>. Reamer <NUM> can be advanced until end wall <NUM> of socket <NUM> engages the proximal surface of depth stop <NUM>. Reamer <NUM> can form prepared surface <NUM> on glenoid G. The high side of the glenoid G can be reamed to remove damaged bone in glenoid G.

<FIG> is a schematic view of a patient-specific drill guide <NUM> mated to partially reamed glenoid G of <FIG> to form central post bore <NUM> in conjunction with drill or reamer <NUM>. Drill guide <NUM> can include base <NUM>, which can be patient-specific to mate with partially reamed glenoid G, and cup <NUM>, which can be shaped to receive reamer <NUM> and positioned to align central post bore <NUM> in scapula S. Base <NUM> is shaped to align central post bore <NUM> along the anatomic axis of scapula S while accounting for the fact that base <NUM> can be slanted and non-perpendicular to the anatomic axis. Base <NUM> can register on a periphery of glenoid G and a portion of the reamed face of glenoid G. Drill guide <NUM> can also include handle shaft <NUM> that can allow a surgeon to position and steady base <NUM> for performing reaming. Reamer <NUM> can be a standard boss reamer.

<FIG> is a schematic view of a patient-specific peripheral post reamer guide <NUM> being advanced into reamed central post bore <NUM> of <FIG> to form peripheral bores 342A and 342B in conjunction with drill or reamer <NUM>. Reamer guide <NUM> can include center peg <NUM> that can be shaped to mate with central post bore <NUM> to align peripheral bores 348A and 348B with respect to glenoid G. Reamer <NUM> can be a standard reamer. Alternatively, a drill may be used. Patient-specific peripheral post reamer guide <NUM> can allow for reaming of peripheral bores 342A and 342B without the need for inserting additional guide pins into glenoid G.

<FIG> is a schematic view of the augmented baseplate <NUM> of FIG. 19A mounted onto partially reamed glenoid G so that slanted bone face <NUM> and fixation posts <NUM>, 310A and 310B mate with prepared glenoid G. Before augmented baseplate <NUM> is implanted, preparation of glenoid G can be performed with a patient-specific glenoid trial having a full augment (not shown). After confirmation of the reaming of glenoid G, posts <NUM>, 310A and 310B of augmented baseplate <NUM> can be inserted into bores <NUM>, 342A and 342B, respectively, of scapula S. A standard impactor can be used to insert augmented baseplate <NUM> and bone cement can also be used in bores <NUM>, 342A and 342B. In one example, augmented baseplate <NUM> will start at an anterior side of glenoid G and angle or slope to the posterior side, as opposed to the procedure described with reference to <FIG> where the angle or slope starts at the midline of glenoid G.

The methods, implants and tools described herein are advantageous over previous systems. For example, the patient-specific augment reamer guides can allow for precise reaming of a glenoid with minimal bone removal, and can allow for accurate fitting with patient-specific implants. The patient-specific guides can allow for placement of guide pins, such as Steinmann Pins, at the angle of pathologic glenoid for face reaming, or to place guide pins along the main axis of the glenoid vault. The patient-specific guides can allow for reaming of glenoid bosses (e.g., with standard reamers) and can be made so as to not require placement of a second pin in the glenoid. The patient-specific augmented implants can be made for various types of glenoid deficiencies, such as B1, B2 or other glenoid classification (anatomic or reverse).

Claim 1:
A ream guide (<NUM>) for a shoulder arthroplasty procedure, the ream guide comprising:
a base (<NUM>) having a first surface and a second surface;
a bone peg (<NUM>) extending substantially perpendicularly from the first surface;
an alignment peg (<NUM>) extending from the first surface spaced from the bone peg; and
a guide peg (<NUM>) extending from the second surface opposite the bone peg (<NUM>) at an oblique angle to the bone peg (<NUM>)
wherein the guide peg (<NUM>) includes an aperture in a side of the guide peg (<NUM>), positioned so as to allow an instrument to extend through the guide peg (<NUM>) in a direction transverse to an axis of the guide peg (<NUM>) and into the bone peg (<NUM>), when inserted into the aperture.