Abstract:
Disclosed herein are systems and methods for shaping bone voids during revision procedures of total knee replacements. The systems disclosed herein generally include a cannulated reamer assembly, a reaming guide assembly, a guide tube assembly, a trial stem assembly, and an optional insertion/removal tool. Metaphyseal reconstruction devices can be used to fill the bone voids in conjunction with the systems and methods disclosed herein.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims the benefit of the filing date of U.S. Provisional Patent Application No. 61/568,808, filed Dec. 9, 2011, the disclosure of which is hereby incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to surgical instruments for preparing a bone to receive a joint prosthesis system, and in particular relates to fully guided surgical reaming instruments for use in total knee replacement revision procedures. 
     BACKGROUND OF THE INVENTION 
     Joint replacement surgery is a common orthopedic procedure for joint such as the shoulder, hip, knee, ankle and wrist. Prior to implanting prosthetic components in a joint of a patient, a surgeon generally has to resect at least a portion of the patient&#39;s native bone in order to create a recess or cavity for receiving at least a portion of the prosthetic components being implanted. During the process of resecting bone, a surgeon generally only resects the amount of bone that is needed in order to implant the prosthetic components in the joint replacement surgery properly. Once native bone is resected from a joint, it generally can no longer be used in the joint. Thus, the surgeon attempts to maintain as much native structural integrity of the joint as he or she can during the resection process. 
     When prosthetic components fail for any one of a variety of reasons, a revision procedure is often necessary. An issue generally encountered by surgeons replacing joints during a revision procedure is the loss of native bone near the joint being replaced. Defects in a bone adjacent a joint, such as the hip or knee, may occur due to wear and arthritis of the joint, congenital deformity, and following the removal of a failed prosthetic component. When the failed prosthetic component or components are removed from the joint during a revision procedure, it is common for there to have been further native bone loss in the area adjacent the original implant position of the prosthetic component or components. This bone loss is typically due to movement of the component or components after implantation or even degeneration or further degeneration of the bone, which can form bone voids that have unpredictable and non-uniform shapes. 
     When bone voids are observed in either the proximal tibia or distal femur, or both, it is standard surgical practice to fill those voids as part of the surgical procedure. The preferred practice is to fill those voids with weight bearing void fillers, typically made of an implant-grade metal such as titanium. These void fillers may be referred to as metaphyseal reconstruction devices (MRD). The name MRD more accurately reflects functions such as weight bearing that these devices provide. 
     Because the bone voids are typically irregular in shape, preparation of the bone void area is typically required prior to implantation of the MRD. This preparation (typically by reaming, broaching or milling) ensures there is sufficient room in the bone cavity for the MRD. An accurate fit between the shaped bone cavity and the MRD is important for establishing joint line, and allowing for weight bearing and bone remodeling during the recovery process. 
     Different methods are commonly used to attempt to prepare the bone void area to create an accurate fit between the shaped bone cavity and the MRD. One method is to ream along the intramedullary (IM) axis, followed by broaching. Another method is to ream on the IM axis, followed by freehand burr or rongeur bone removal, which may also be followed by broaching. Problems with these methods include that reaming is performed on the IM axis only, so that void areas at a distance from the IM axis, which commonly occur, can only be resected using manual methods. Moreover, broaching generally has at least two problems. First, a manual operation can be time consuming, particularly in cases of sclerotic bone, which exposes the patient to an increased risk of infection and a longer recovery. Second, in the case of large bone voids, broaching generally needs to be performed in a multi-step process because attempting to remove high volumes of bone in a single broaching step generally requires high impact forces to the bone. Also, freehand bone removal, either powered or unpowered, such as by burr or rongeur, often does not produce accurate cavity shapes to receive predefined prosthetic components. A typical result is that areas remain where the outer walls of the MRD do not contact the cavity, which may lead to undesirable stress distribution and possible loss of bone regrowth. Also typical is the time consuming requirement of iterative bone removal, with multiple checks against the MRD, to obtain a correct fit. 
     Thus, there is a need for a surgical reaming instrument that creates accurate bone cavity geometries in minimal time and that minimizes the necessity for freehand bone removal. There is also a need for enabling surgeons to create bone cavities with a fully guided system. 
     BRIEF SUMMARY OF THE INVENTION 
     According to one aspect of the present invention, a surgical system for preparing a bone. The surgical system comprises a reaming guide assembly, which includes a trial stem having a proximal end and a longitudinal axis. The trial stem is configured to fit into an intramedullary canal in the bone. The reaming guide assembly also comprises a guide tube assembly, which has a distal end portion and a guide tube that is angled with respect to the distal end portion, wherein the distal end portion of the guide tube is coupled to the proximal end of the trial stem such that a longitudinal axis of the guide tube is angled with respect to the longitudinal axis of the trial stem. The surgical system further comprises a cannulated reamer assembly for shaping a bone cavity. The cannulated reamer assembly has a proximal end, a reaming head coupled at a distal end and a cannulation extending through the reaming head and distal end thereof, wherein a longitudinal axis of the cannulated reamer assembly is angled with respect to the longitudinal axis of the trial stem when at least a portion of the guide tube is housed within the cannulation of the cannulated reamer assembly. 
     In one embodiment, the proximal end of the cannulated reamer assembly is configured to engage a torque applying device, for example a drill or manual device. 
     According to another embodiment, the cannulated reamer assembly further comprises a quick connect mechanism, which has a ball detent engaged to a distal end of a reamer shaft. The ball detent selectively engages a notch in a proximally protruding extension of the reaming head in order to couple the reamer shaft to the reamer head. 
     According to another aspect of the present invention, the reaming guide assembly further comprises a handle assembly for manipulating the reaming guide assembly. The handle assembly is coupled to the proximal end of the trial stem such that a surgeon can manipulate the reaming guide assembly while the trial stem is located in the intramedullary canal. 
     Yet another aspect of the current invention the surgical system further comprises an insertion/removal tool for efficient removal of the reaming guide assembly from the bone canal. The insertion/removal tool has a distal end configured for selective engagement to the proximal end of the trial stem. 
     In one embodiment, the guide tube assembly and the handle assembly are fixed with respect to each other and are rotatably mounted to the proximal end of the trial stem such that a surgeon may rotate the guide tube assembly and the handle assembly about the longitudinal axis of the trial stem while the guide tube assembly and the handle assembly partially reside within a central pocket in the bone. 
     According to another aspect of the current invention, the surgical system further comprises a tibial implant for implantation into the reamed bone void created by the reaming guide and cannulated reamer assemblies. The tibial implant is shaped to match contours of the bone cavity and has a central opening defined therethrough, wherein the central opening is configured to permit the passage of the trial stem or a stem boss of a tibial baseplate into the intramedullary canal. 
     The shape of the tibial implant may be realized in the form of at least two outer surfaces being blended tapered conical surfaces that substantially match the contours of the bone cavity. 
     In one embodiment, the tibial implant further comprises a proximal surface, a lateral wall, a medial wall and a fin clearance for positional adjustment of the tibial baseplate. The fin clearance defines a groove that extends from the lateral wall through the medial wall and extends through the proximal surface. 
     According to another embodiment of the present invention, the surgical system further comprises a femoral implant for implantation into the bone cavity. The femoral implant is shaped to match contours of the bone cavity and having a central opening defined therethrough, wherein the central opening is configured to permit the passage of a femoral stem into the intrameduallry canal. 
     The shape of the femoral implant may be realized in the form of at least two outer surfaces being tapered conical surfaces that substantially match the contours of the bone cavity. 
     In one embodiment, the femoral implant further comprises a posterior wall, an anterior wall and a first and second clearance space, wherein the first clearance space defines a recess in the posterior wall shaped to accommodate a femoral cam box, and the second clearance space defines a cut in anterior wall shaped to accommodate an anterior chamfer of a femoral implant. 
     Another aspect of the present invention is a surgical method for preparing bone. The method comprises placing a reaming guide assembly at least partially into an already formed intramedullary canal and an already formed central pocket. The central pocket is in fluid communication with the intramedullary canal. The reaming guide assembly comprises a trial stem and guide tube assembly. The trial stem has a proximal end configured to be received in the intramedullary canal, and the guide tube assembly has a distal end portion coupled to the proximal end of the trial stem and a guide tube angled with respect to the distal end portion. The guide tube assembly at least partially resides in the central pocket when the trial stem is fully seated in the intraumeddulary canal. The method further comprises coupling a cannulated reamer assembly to the guide tube assembly such that the proximal end of the guide tube assembly is housed within a cannulation of the cannulated reamer assembly, and the reaming head contacts bone at a first position. Further, there is a step of driving the cannulated reamer to a predetermined depth into the bone, thereby forming a first bone cavity adjacent to the central pocket. 
     In one embodiment, the reaming guide assembly further comprises a handle assembly. The handle assembly being fixed at the proximal end of the trial stem such that the handle assembly at least partially resides in the central pocket when the trial stem is fully seated in the intramedullary canal. 
     A further aspect of the method comprises the step of manipulating the handle assembly, thereby placing the reaming guide assembly in an optimum angular position. 
     In yet another embodiment, the guide tube assembly and the handle assembly are fixed with respect to each other and are rotatably mounted to the proximal end of the trial stem. 
     According to an additional aspect of the method, the method further comprises the step of rotating the handle assembly and guide tube assembly to a second position while partially residing within the central pocket. 
     In one embodiment, the method includes a step of reaming bone at the second position with the cannulated reamer assembly placed over the guide tube assembly, thereby forming a second bone cavity adjacent to the central pocket. 
     According to another embodiment, is a method for preparing bone to receive a revision prosthesis, which comprises the step of reaming bone generally along an intramedullary canal with an intramedullary reamer having a proximal end. Another step of the method is placing a cannulated reamer assembly having a reaming head over the proximal end of the intramedullary reamer such that the reaming head contacts bone. Further, the method includes driving the cannulated reamer into bone to a predetermined depth, thereby forming a central bone pocket. The method further comprising removing the intramedullary reamer and cannulated reamer assembly from the intramedullary canal and central bone pocket. Additionally, there is a step of placing a reaming guide assembly at least partially into the intramedullary canal and central bone pocket. The reaming guide assembly comprises a trial stem, a guide tube assembly, and a handle assembly. The trial stem has a proximal end and is configured to fit into the intramedullary canal. Further, the guide tube assembly has a proximal end and distal end that is rotatably fixed to the proximal end of the trial stem at an oblique angle such that the guide tube assembly at least partially resides in the central bone pocket when the trial stem is fully seated in the intramedullary canal. The handle assembly is fixed at the proximal end of the trial stem such that the handle assembly at least partially resides in the central bone pocket when the trial stem is fully seated in the intramedullary canal. Also included is the step of placing the cannulated reamer assembly over the proximal end of the guide tube assembly such that the reaming head contacts bone at a first position. The method further comprises the step of driving the cannulated reamer into bone to a predetermined depth, thereby forming a first bone cavity adjacent to the central bone pocket. 
     In one embodiment, the method further comprises the step of rotating the handle assembly and guide tube assembly with respect to the trial stem while partially residing within the central pocket to a second position. 
     According to another aspect of the invention, the method further comprises the step of reaming bone at the second position with the cannulated reamer assembly placed over the guide tube assembly, thereby forming a second bone cavity adjacent to the central pocket. 
    
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         FIG. 1A  shows an assembled perspective view of one embodiment of a surgical reaming instrument of the present invention. 
         FIG. 1B  shows a partially exploded perspective view of the surgical reaming instrument shown in  FIG. 1A  with a trial stem separated therefrom. 
         FIG. 2A  shows an exploded perspective view of a reaming guide the surgical reaming instrument shown in  FIG. 1A . 
         FIG. 2B  shows a partially assembled perspective view of a spring detent of the reaming guide shown in  FIG. 2A  with a spring detent thereof being visible. 
         FIG. 2C  shows an assembled perspective view of the reaming guide shown in  FIG. 2A . 
         FIG. 3A  shows a side view of a reaming guide assembly and a guide tube assembly. 
         FIG. 3B  shows a cross section view of the reaming guide assembly and the guide tube assembly taken along line  3 B- 3 B of  FIG. 3A . 
         FIG. 3C  shows an enlarged view of an attachment mechanism shown in  FIG. 3B . 
         FIG. 4A  shows a side view of a reaming guide assembly and a guide tube assembly with a locking rod. 
         FIG. 4B  shows a cross section view of the reaming guide assembly and the guide tube assembly with locking rod taken along line  4 B- 4 B of  FIG. 4A . 
         FIG. 5A  shows an exploded perspective view of a handle assembly of one embodiment of the surgical reaming instrument of the present invention. 
         FIG. 5B  shows a side view of the handle assembly of  FIG. 5A . 
         FIG. 5C  shows a cross section view of the handle assembly taken along line  5 C- 5 C of  FIG. 5B . 
         FIG. 5D  shows a perspective view of a handle assembly detached from a guide body assembly and guide tube assembly. 
         FIG. 6A  shows an exploded perspective view of an insertion/removal tool for use with a surgical reaming instrument. 
         FIG. 6B  shows a perspective view of an assembled insertion/removal tool for use with a surgical reaming instrument. 
         FIG. 6C  shows a perspective view of an insertion/removal tool connected to a surgical reaming instrument. 
         FIG. 6D  shows a side view of an insertion/removal tool connected to a surgical reaming instrument. 
         FIG. 6E  shows a cross section view of an insertion/removal tool connected to a surgical reaming instrument taken along line  6 E- 6 E of  FIG. 6D . 
         FIG. 7A  shows a side view of a cannulated reamer assembly. 
         FIG. 7B  shows a cross section view of a cannulated reamer assembly taken along line  7 B- 7 B of  FIG. 7A . 
         FIG. 7C  shows an exploded perspective view of one embodiment of a cannulated reamer assembly of the present invention. 
         FIG. 7D  shows an assembled perspective view of the cannulated reamer assembly of  FIG. 7C . 
         FIG. 8A  shows a perspective view of a preparatory reaming step in a tibial bone. 
         FIG. 8B  shows a side view of a preparatory reaming step in a tibial bone. 
         FIG. 8C  shows a cross section view of the preparatory reaming step in a tibial bone taken along line  8 C- 8 C of  FIG. 8B . 
         FIG. 9A  shows a perspective view of a first reaming step in a tibial bone using a cannulated reamer assembly. 
         FIG. 9B  shows a side view of a tibial bone after a first reaming step has been completed. 
         FIG. 9C  shows a cross section view of a tibial bone after a first reaming step has been completed with a cannulated reaming assembly taken along line  9 C- 9 C of  FIG. 9B . 
         FIG. 10A  shows a perspective view of a surgical reaming instrument and tibial bone being prepared for a second reaming step. 
         FIG. 10B  shows a perspective view of a surgical reaming instrument and tibial bone after the second reaming step has been completed. 
         FIG. 10C  shows a side view of a surgical reaming instrument and tibial bone after the second reaming step has been completed. 
         FIG. 10D  shows a cross section view of a surgical reaming instrument and tibial bone after the second reaming step has been completed taken along line  10 D- 10 D of  FIG. 10C . 
         FIG. 11A  shows a side view of a tibial bone after the second reaming step has been completed. 
         FIG. 11B  shows a cross section view of a tibial bone after the second reaming step has been completed taken along line  11 B- 11 B of  FIG. 11A . 
         FIG. 11C  shows a side view of a tibial bone after the third reaming step has been completed. 
         FIG. 11D  shows a cross section view of a tibial bone after the third reaming step has been completed taken along lien  11 -D- 11 D of  FIG. 11C . 
         FIG. 11E  shows a top view of a tibial bone after the third reaming step has been completed. 
         FIGS. 12A-D  show different views of one embodiment of a tibial metaphyseal reconstruction device of the present invention. 
         FIG. 13A  shows a perspective view of the tibial metaphyseal reconstruction device shown in  FIGS. 12A-D  prior to implantation into a tibial bone. 
         FIG. 13B  shows a side view of the tibial bone after a metaphyseal reconstruction device has been implanted. 
         FIG. 13C  shows a cross section view of the tibial bone after a metaphyseal reconstruction device has been implanted, taken along line  13 C- 13 C of  FIG. 13B . 
         FIGS. 14A-D  show different views of one embodiment of a femoral metaphyseal reconstruction device of the present invention. 
         FIG. 14E  shows a perspective view of the femoral metaphyseal reconstruction device shown in  FIGS. 14A-D  prior to attachment to a femoral implant. 
         FIG. 14F  shows a perspective view of the femoral metaphyseal reconstruction device after attachment to a femoral implant. 
     
    
    
     DETAILED DESCRIPTION 
     As used herein, when referring to the surgical reaming instrument of the present invention, the term “proximal” means closer to the surgeon or in a direction toward the surgeon and the term “distal” means more distant from the surgeon or in a direction away from the surgeon. The term “anterior” means towards the front part of the body or the face and the term “posterior” means towards the back of the body. The term “medial” means toward the midline of the body and the term “lateral” means away from the midline of the body. 
       FIG. 1A  shows a surgical reaming instrument  10 . The surgical reaming instrument  10  generally includes a reaming guide assembly  100 , a guide tube assembly  200 , a handle assembly  300 , and a trial stem  400 , each of which will be described in further detail below.  FIG. 1B  shows the surgical reaming instrument  10  with the trial stem  400  removed from the reaming guide assembly  100 . 
       FIGS. 2A-C  show the reaming guide assembly  100  in detail.  FIG. 2A  shows an exploded view of the components of the reaming guide assembly  100 . Reaming guide assembly  100  generally includes a reaming guide  102 , a reaming guide collar  104 , and a spring detent  116 . The reaming guide  102  includes a handle receiving portion  118  and a guide tube receiving portion  124 . Reaming guide  102  further includes a distally projecting extension  106 , which is configured to fit within a hollow proximal portion of the reaming guide collar  104 . When the distally projecting extension  106  is within the hollow proximal portion of the reaming guide collar  104 , collar apertures  114  align with a notch  108  in the distally projecting extension  106 . This allows for reaming guide locking pins  112  to be placed through collar apertures  114  and sit within the notch  108  in the distally projecting extension  106 . When the locking pins  112  are in place, the reaming guide  102  and the reaming guide collar  104  are restricted from moving distally or proximally with respect to each other. 
       FIG. 2B  shows a detailed view of spring detent  116  located between partially assembled reaming guide  102  and reaming guide collar  104 . Referring to  FIGS. 2A-B , spring detent  116  includes ridges  128  and a protrusion  126 . Spring detent  116  is generally horseshoe shaped and surrounds a portion of the distally projecting extension  106  proximal to the notch  108  when the distally projecting extension  106  is within the reaming guide collar  104 . The spring detent protrusion  126  fits into one of apertures  130 ,  132  on the underside of the reaming guide  102 . Additionally, each ridge  128  in the spring detent  116  sits within a respective collar notch  110  in the reaming guide collar  104 . When a surgeon or other operating room personnel inserts the reaming guide  102  into the reaming guide collar  104 , the spring detent protrusion  126  preferably engages the aperture  130 , for instance, and both the spring detent  116  and reaming guide  102  can be rotated until the ridges  128  engage their respective collar notches  110 . When the ridges  128  engage the collar notches  110 , this engagement can be felt and feedback is provided to ensure that the reaming guide  102  is in a position such that locking pin aperture  132  is aligned with another of the collar notches  110 .  FIG. 2C  shows the reaming guide assembly  100  when reaming guide  102 , reaming guide collar  104  and spring detent  116  are all assembled. 
       FIGS. 3A-C  show detailed views of the guide tube assembly  200  together with the reaming guide assembly  100 .  FIG. 3A  shows a side view of the reaming assembly  100  and the guide tube assembly  200 , along with section origin  3 B. 
       FIG. 3B  shows a cross section of the reaming guide assembly  100  and guide tube assembly  200  along section origin  3 B.  FIG. 3C  shows an enlarged view of circular section D from  FIG. 3B . Referring to  FIGS. 3B-C , a locking pin  204  is seated partially within the guide tube receiving portion  124  and further through one of locking pin apertures  130 ,  132 . The locking pin  204  is surrounded by a coil spring  206  dimensioned such that the head of locking pin  204  cannot pass through coil spring  206 , and coil spring  206  cannot pass through locking pin aperture  132 . The coil spring  206  and locking pin  204  are further dimensioned so that when the head of locking pin  204  is resting on the coil spring  206  with no additional force applied, the distal end of the locking pin  204  does not enter any portion of a collar notch  110 . Although in  FIGS. 3B-C  there is no force being applied to the locking pin  204  other than the weight of the locking pin  204  itself, the locking pin  204  is shown in the locked position for purposes of illustration (i.e. the distal end of the locking pin  204  is within a collar notch  110 ). The locking pin  204 , when in the locked position, prevents relative rotation between the reaming guide  102  and the reaming guide collar  104  since the locking pin  204  rests in one of collar notches  110  of reaming guide collar  104 . 
     Guide tube receiving portion  124  of the reaming guide  102  may include one or more rinse holes  209  to improve the ability to clean the surgical reaming instrument  10 . Once the locking pin  204  is seated within the guide tube receiving portion  124  and further through locking pin aperture  132 , a guide tube  202  may be inserted into the guide tube receiving portion  124 . The guide tube  202  may be permanently fixed within the guide tube receiving portion  124 , for example, by welding. As will be explained in more detail below, guide tube  202  is used to act as a guide for a cannulated reamer assembly  600  when reaming a bone. 
       FIGS. 4A-4B  show detailed views of the guide tube assembly  200  and the reaming guide assembly  100  with locking rod  208  inserted into guide tube  202 .  FIG. 4A  shows a side view of the reaming assembly  100  and the guide tube assembly  200 , along with section origin  4 B.  FIG. 4B  shows a cross section of the reaming guide assembly  100  and guide tube assembly  200  along section origin  4 B. Locking rod  208  is inserted into guide tube  202  and can be fixed, for example, by threading the locking rod  208  into corresponding threads on the inside of guide tube  202 . When the locking rod  208  is fully or nearly fully inserted into the guide tube  202 , a proximal portion of the locking rod  208  clears the guide tube  202  and provides a handle  210  for the surgeon to manipulate reaming guide  102 . By rotating the locking rod handle  210 , and thus the locking rod  208 , the distal end of the locking rod  208  makes contact with, and applies force to, the head of the locking pin  204 . This rotation can be continued until the locking pin  204  is fully driven into a collar notch  110 . Once fully driven into the collar notch  110 , the system is in the locked position and the reaming guide  102  is prevented from rotating relative to the reaming guide collar  104 . 
       FIG. 5A  shows an exploded view of the handle assembly  300 .  FIG. 5B  shows a side view of the handle assembly  300  with section origin  5 C.  FIG. 5C  shows a cross section of the handle assembly  300  along section origin  5 C.  FIG. 5D  shows the handle assembly  300  fully assembled and exploded from the remainder of the surgical reaming instrument  10 . Referring now to  FIGS. 5A-D , handle assembly  300  generally includes a handle  302 , to allow the surgeon to grip the surgical reaming instrument  10 , and an attachment screw  304 , to attach the handle assembly  300  to the reaming guide  102 . Alignment pins  303  are inserted into their respective flanking apertures  122  of the handle receiving portion  118  of the reaming guide  102 . These alignment pins  303  align the screw aperture  306  of the handle assembly  300  with the center aperture  120  of the handle receiving portion  118  of the reaming guide  102 . Once aligned, the surgeon can insert the attachment screw  304  into the screw aperture  306  and further into the center aperture  120  by gripping and rotating the screw handle  308  so that the attachment screw  304  threads fully through the screw aperture  306 . Once the attachment screw  306  is fully inserted into the screw aperture  306 , the screw collar  315  sits distal to the retaining pin aperture  312 . At this point, the surgeon can insert the screw retaining pin  310  into the retaining pin aperture  312  such that the screw retaining pin  310  sits proximal the screw collar  314 . This ensures that the attachment screw  304  is locked into place and cannot exit the screw aperture  306 . 
       FIG. 6A  shows an exploded view of an optional insertion/removal tool  500 .  FIG. 6B  shows a view of the assembled insertion/removal tool  500 . The insertion/removal tool  500  is optionally used to insert or remove the surgical reaming instrument  10 . Referring to  FIGS. 6A-B , an insertion/removal tool  500  generally includes a tool body  502  and a locking lever  504 . Tool body  502  includes a slot  518  into which the locking lever  504  is installed. Locking lever  504  includes an aperture  516  that aligns with pivot pin apertures  514  on each side of the tool body  502 . Pivot pin  506  can be inserted through locking lever aperture  516  and both pivot pin apertures  514  on the tool body  502 . The pivot pin  506  allows the locking lever  504  to pivot about the pivot pin  506 . Additionally, the proximal end of the body slot  518  includes a preload spring  508 . The preload spring  508  contacts the locking lever actuator  520 . When the locking lever actuator  520  is pressed, the preload spring  508  compresses and the locking lever  504  pivots about pivot pin  506 , ultimately causing the lever hook  510  to move away form the body  502  of the insertion/removal tool  500 . The end of the tool  512  may optionally be configured to match a universal instrument handle. 
       FIG. 6C  shows the insertion/removal tool  500  assembled with the reaming guide assembly  100 , the guide tube assembly  200 , and the handle assembly  300 .  FIG. 6D  shows a side view of the illustration in  FIG. 6C  along with section origin  6 E.  FIG. 6E  shows a cross section view of the illustration in  FIG. 6D  along section origin  6 E. Referring to  FIGS. 6C-E , the insertion/removal tool  500  can be slid distally toward the guide body receiving portion  124  of the reaming guide assembly  100  until the lever hook  510  snaps into a hook receiving portion  150  of the guide body receiving portion  124  of the reaming guide assembly  100 . The preload spring  508  provides enough force on the proximal end of the locking lever  504  to keep the insertion/removal tool  500  engaged with the reaming guide assembly  100 . If a surgeon, for instance, desires to detach the insertion/removal tool  500  from the reaming guide assembly  100 , he simply applies pressure to the locking lever actuator  520  such that the locking lever  504  pivots about pivot pin  506  and the lever hook  510  disengaged from the reaming guide assembly  100 . 
       FIG. 7A  shows a side view of a cannulated reamer assembly  600  with section origin  7 B. Cannulated reamer assembly  600  generally includes reaming head  602  and reamer shaft assembly  604 . Reamer shaft assembly includes quick connect mechanism  606 , shaft handle  607  and drill attachment end  608 . The surgeon can grip the quick connect mechanism  606  and insert the reaming head  602  into the distal end of the reamer shaft assembly  604  to connect the reaming head  602  to the reamer shaft assembly  604 . To disconnect the reaming head  602  from the reamer shaft assembly  604 , the surgeon can grip the shaft handle  607  and pull the reamer shaft assembly  604  proximally away from the reaming head  602 . The reamer shaft assembly  604  further includes a drill attachment end  608  on the proximal end of the reamer shaft assembly  604 . The drill attachment end  608  can be attached to a drill, such as an electric or pneumatic drill, in order to drive the cannulated reamer assembly  600 . Reaming head  602  may include a depth indicator  605 , such as a groove in the reaming head  602 , that gives feedback to the surgeon, such as visual feedback, to notify the surgeon that the reaming head  602  has traveled a predetermined distance. Reaming head  602  can also contain a tapered distal end  603 . 
       FIG. 7B  shows a cross section of the cannulated reamer assembly  600  along the section origin  7 B. Reaming head  602  and reamer shaft assembly  604  both include cannulations  612  that allow the cannulated reamer assembly  600  to slide over a rod, such as the guide tube  202  of the guide tube assembly  200  or over the rod of a traditional intramedullary (IM) reamer. The reaming head  602  also includes a counterbore  610  to allow the reaming head  602  to clear the guide tube receiving portion  124  of the reaming guide assembly  100 . Additionally, the reamer shaft assembly  604  may include a viewing port  614  located at the proximal end of the cannulation  612  to give the surgeon visual feedback regarding whether or not the cannulated reamer assembly  600  has “bottomed out.” Essentially, as long as the rod over which the cannulated reamer assembly  600  is placed cannot be seen through the view port  614 , there is no danger of “bottoming out.” Once the rod can be seen through the view port  614 , the surgeon, for instance, can view whether the cannulated reamer assembly  600  is close to travelling the full distance of which it is capable before the rod makes contact with the proximal closed end of the cannulation  612  of the reamer shaft assembly  604 .  FIG. 7C  shows an exploded view of the cannulated reamer assembly  604  with the reaming head  602  separated from the reamer shaft assembly  604 .  FIG. 7D  shows the cannulated reamer assembly  604  fully assembled. 
     An example of one method of use of the invention will now be described. Referring now to  FIGS. 8A-C , the beginning of one method of a revision procedure is shown. For example, in a revision procedure of a total knee replacement surgery, the initial step is to ream the bone  700  generally along the IM canal. Although the IM reamer  704  is illustrated here as distally reaming the tibia beginning at the tibial plateau  702 , this is merely an example. The IM reamer  704  could also proximally ream the femur beginning at the distal end of the femur in substantially the same manner.  FIG. 8B  shows the initial step along with section origin  14 C, and  FIG. 8C  shows a cross section of the initial step along section origin  14 C. As can be seen, the IM reamer  704  enters through the initial bone void  706  that was originally created during a previous knee replacement surgery, for example. 
       FIG. 9A  shows the first step following the initial tibial or femoral IM canal preparation. The IM reamer  704  used to initially prepare the IM canal is left in place and the cannulation  612  of the cannulated reaming assembly  600  is placed over the proximal end of the IM reamer  704 . The surgeon then reams over the stem of the IM reamer  704  using the cannulated reaming assembly  600 . The reaming head  602  is driven distally into the tibial bone until the surgeon, optionally using the depth indicator  605  as a guide, determines that the proper depth has been reached based on the dimensions of a MRD to be implanted into the bone.  FIG. 9B  shows a side view of the bone  700  after this reaming step has been performed, along with section origin  9 C.  FIG. 9C  shows a cross section of the bone following this reaming step along section origin  9 C. As can be seen, one void space in the bone  700  is the generally cylindrical preparatory IM reaming void  708  created by the initial preparation step with the IM reamer  704 . A central pocket  710  created in the initial reaming step corresponds in shape to the tapered distal end  603  of the reaming head  602 . 
       FIG. 10A  shows the reaming guide setup for the second reaming step. The cannulated reaming assembly  600  first is removed from the IM reamer  704 . Then, the fully assembled reaming guide assembly  100 , guide tube assembly  200 , handle assembly  300 , and optional insertion/removal tool  500  are placed near bone  700 .  FIG. 10B  shows the surgical reaming instrument  10  inserted in the central pocket  710  in the bone after the second reaming step has been completed.  FIG. 10C  shows a side view of  FIG. 10B  along with section origin  10 D.  FIG. 10D  shows a cross section of  FIG. 10C  along section origin  10 D. Once inserted, as seen in  FIG. 10D , the reaming guide  102  makes contact with a portion of the bone  700  surrounding central pocket  710 . The cannulated reaming assembly  600  is then preferably inserted over the guide tube  202  of the guide tube assembly  200 . The surgeon may use the handle  302  of the handle assembly  300  for optimum angular positioning of the reaming guide  102 . The reaming head  602  of the reaming assembly  600  is then driven, either manually or with a drill, distally along the guide tube  202  to ream the bone  700 . The reaming guide assembly  100  acts as a depth stop to ensure that reaming head  602  can only travel a predetermined distance. Although the counterbore  610  of the reaming head  602  will pass over the guide tube receiving portion  124  of the reaming guide assembly  100 , the remainder of the reaming guide assembly  100  will act as a stop for the distal end of the reaming head  602 . 
       FIG. 11A  shows a side view of the bone  700  after the second reaming step is completed, along with section origin  11 B.  FIG. 11B  shows a cross section of the bone  700  along section origin  11 B. In addition to the central pocket  710 , a medial reaming void  712  preferably exists along the path taken by the reaming head  602  in the second reaming step. If necessary, depending on the size and the shape of the bone void, a third reaming step can be undertaken. With the surgical reaming instrument  10  in the bone void, the reaming head  602  is moved proximally along the guide tube  202  until it clears the bone  700 . The locking rod handle  210  of the locking rod  208  is preferably rotated to release the force on the locking pin  204 . The coil spring  206  will cause the locking pin  204  to move proximally and clear that collar notch  110 . Once the locking pin  204  clears the collar notch  110 , the system is in what may be referred to as an unlocked position and the reaming guide  102  can rotate in relation to the reaming guide collar  104 . One in the unlocked position, the surgeon can use the handle  302  to rotate the reaming guide  102  into the desired position for a further reaming step. Angular stops may be provided in the handle  302  so that angular rotation between reaming steps can be accurately controlled. Once in place, the locking rod  208  is manipulated to force the locking pin  204  back into the locking position so that the third reaming step can be performed. The third reaming step is preferably completed in substantially the same manner as the second reaming step, with the only difference being the portion of the bone  700  being reamed.  FIG. 11C  shows a side view of the bone  700  after the third reaming step has been performed, along with section origin  11 D.  FIG. 11D  shows a cross section of the bone  700  along section origin  11 D after the third reaming step has been performed. As can be seen, in addition to central pocket  710  and medial reaming void  712 , there is now a lateral reaming void  714  created as a result of the third reaming step.  FIG. 11E  shows a top view of bone  700  after the third reaming step. The IM axis  720  corresponds to the center of the central pocket  710  and preparatory IM reaming void  708 . The medial reaming axis  722  corresponds to the center of the medial reaming void  712 , and the lateral reaming axis  724  corresponds to the center of the lateral reaming void  714 . When the reaming is complete, the bone  700  is ready to receive a void filler prosthetic component, such as an MRD, for example. In certain embodiments, the three aforementioned reaming steps do not have to be performed in any particular order, and in other embodiments, not all three of the reaming steps are performed. 
       FIGS. 12A-D  show different views of a MRD. In this illustrative embodiment, the MRD is a tibial MRD  800 . The tibial MRD  800  is placed within the one or more reaming voids  710 ,  712  and  714  in the bone  700 . The tibial MRD  800  includes a central opening  802  to allow insertion of a trial stem  400 , in this case a tibial stem. The central opening  802  also allows for insertion of the stem boss of a tibial baseplate (not shown), the tibial baseplate being engaged to the proximal side of the tibial MRD  800 . The tibial MRD  800  can also include fin clearances  804  to permit rotation and position adjustment of the tibial baseplate. The outer surfaces  806  of the tibial MRD  800  are configured to match the dimensions of surfaces of the bone  700  created by a particular cannulated reamer assembly  600 . In this illustrative embodiment, outer surfaces  806  include three blended tapered conical surfaces that match the surface in the bone  700  created by the three reaming steps described above. 
       FIG. 13A  shows the tibial MRD  800  prior to insertion into the void in the bone  700  consisting of the central pocket  710 , the medial reaming void  712  and the lateral reaming void  714 .  FIG. 13B  shows a side view of the bone  700  with the tibial MRD  800  inserted, along with section origin  13 C.  FIG. 13C  shows a cross section along section origin  13 C of the bone  700  with tibial MRD  800  inserted. 
       FIGS. 14A-D  show, respectively, superior, isometric, anterior, and lateral views of an MRD. In this illustrative embodiment, the MRD is a femoral MRD  900 . The femoral MRD  900  is generally similar to the tibial MRD  800 , with the main difference being that the femoral MRD  900  is inserted into the bone void created by a reaming process on the distal end of the femur. The femoral MRD  900  includes a central opening  902  to allow for passage of a femoral stem. The femoral MRD  900  also can include tapered conical surfaces  904  to correspond to the particular shape of the bone voids created in the reaming process. Additionally, the femoral MRD  900  can include a first clearance space  906  for a femoral cam box, if needed, and a second clearance space  908  for the anterior chamfer of a femoral implant.  FIGS. 14E and 14F  show the femoral MRD  900  before and after attachment to the femoral implant  910 , respectively. In this illustration, the femoral stem is omitted from the femoral stem attachment site  912  for clarity. The present invention can be used for multiple types of MRD implantation. For example, cemented MRDs can be used within the scope of this invention, in which there is a gap between the MRD and the balance of the implant construct, which is filled with bone cement during the procedure. Additionally, locked MRDs can be used within the scope of this invention, in which a mechanical connection, such as a taper lock, is made between the MRD and the balance of the implant construct. 
     There are many benefits of performing a revision procedure with the surgical reaming instrument of the present invention. For example, all bone removal steps may be fully guided without the need for any freehand bone removal. Additionally, the present invention provides a surgeon with the option of performing a guided ream of the bone either by hand or by using a powered source, such as a drill. Further, the instruments generally anatomically match typical bone voids observed in surgery. For example, the prepared cavity can be wider in the medial/lateral direction than in the anterior/posterior direction. Another related benefit is that the instrument has the capability to prepare asymmetric cavities, such as larger cavities on the medial side than the lateral side, which is often seen in cases of tibial bone voids. Importantly, because of the precision of control allowed when using this instrument, the shape of the cavity can be precisely controlled which allows for stock MRDs to accurately fit into the bone void without dependence on the technique of the particular surgeon performing the surgery. Related to this is that the symmetric, geometrically defined shape of the MRD simplifies the setup and machining of void fillers. Yet another benefit of an embodiment of this invention is that it allows a cannulated reamer set to consist of differently sized modular reaming heads and a single shaft to fit all reaming head sizes. This results in a reduced cost and size of the instrument set. The MRDs described herein can be made of any biocompatible material such as polymer and stainless steel, for example. 
     Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention.