Surgical reaming instrument for shaping a bone cavity

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.

The invention claimed is: 
     
       1. A surgical system for preparing bone comprising:
 a reaming guide assembly including:
 a trial stem having a proximal end and a longitudinal axis, the trial stem configured to fit into an intramedullary canal in the bone, and 
 a guide tube assembly having a guide tube 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; and 
   a cannulated reamer assembly for shaping a bone cavity, the cannulated reamer assembly having 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, and   wherein the cannulated reamer assembly is both rotatable about and slidable along the guide tube during operation.   
     
     
       2. The surgical system of  claim 1 , wherein the proximal end of the cannulated reamer assembly is configured to engage a torque applying device. 
     
     
       3. The surgical system of  claim 1 , wherein the cannulated reamer assembly further comprises a quick connect mechanism having a ball detent engaged to a distal end of a reamer shaft, the ball detent selectively engaging a notch in a proximally protruding extension of the reaming head in order to couple the reamer shaft to the reamer head. 
     
     
       4. The surgical system of  claim 1 , wherein the reaming guide assembly further comprises a handle assembly for manipulating the reaming guide assembly, the handle assembly 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. 
     
     
       5. The surgical system of  claim 4 , further comprising an insertion/removal tool for efficient removal of the reaming guide assembly from the bone canal, the insertion/removal tool having a distal end configured for selective engagement to the proximal end of the trial stem. 
     
     
       6. The surgical system of  claim 4 , wherein 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. 
     
     
       7. The surgical system of  claim 6 , further comprising a tibial implant for implantation into the bone cavity prepared by the reaming guide and cannulated reamer assemblies, the tibial implant being 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 the trial stem or a stem boss of a tibial baseplate into the intramedullary canal. 
     
     
       8. The surgical system of  claim 7 , wherein the shape of the tibial implant includes at least two outer surfaces being blended tapered conical surfaces that substantially match the contours of the bone cavity. 
     
     
       9. The surgical system of  claim 8 , wherein 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. 
     
     
       10. The surgical system of  claim 6 , further comprising a femoral implant for implantation into the bone cavity, the femoral implant being 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 intramedullary canal. 
     
     
       11. The surgical system of  claim 10 , wherein the shape of the femoral implant includes at least two outer surfaces being tapered conical surfaces that substantially match the contours of the bone cavity. 
     
     
       12. The surgical system of  claim 11 , wherein 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, wherein the second clearance space defines a cut in anterior wall shaped to accommodate an anterior chamfer of a femoral implant. 
     
     
       13. A surgical method for preparing bone comprising the steps of:
 placing a reaming guide assembly at least partially into an already formed intramedullary canal and central pocket that is in fluid communication with the intramedullary canal, the reaming guide assembly comprising a trial stem and guide tube assembly, the trial stem having a proximal end configured to be received in the intramedullary canal, the guide tube assembly having a guide tube coupled to the proximal end of the trial stem such that a longitudinal axis of the guide tube is angled with respect to a longitudinal axis of the trial stem;   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; and   driving the cannulated reamer along the guide tube to a predetermined depth into the bone, thereby forming a first reamed bone cavity adjacent to the central pocket.   
     
     
       14. The method of  claim 13 , wherein 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. 
     
     
       15. The method of  claim 13 , wherein the guide tube assembly is rotatably mounted to the proximal end of the trial stem such that the guide tube assembly can be rotated about the trial stem from the first position to a second position. 
     
     
       16. The method of  claim 15 , further comprising the step of rotating the handle assembly and guide tube assembly to the second position while partially residing within the central pocket. 
     
     
       17. The method of  claim 16 , further comprising the step of reaming bone at the second position with the cannulated reamer assembly placed over the guide tube assembly, thereby forming a second reamed bone cavity adjacent to the central pocket. 
     
     
       18. A method for preparing bone to receive a revision prosthesis comprising the steps of:
 reaming the bone generally along an intramedullary canal with an intramedullary reamer having a proximal end;   placing a cannulated reamer assembly having a reaming head over the proximal end of the intramedullary reamer such that the reaming head contacts the bone;   driving the cannulated reamer into bone to a predetermined depth, thereby forming a central bone pocket;   removing the intramedullary reamer and cannulated reamer assembly from the intramedullary canal and central bone pocket;   placing a reaming guide assembly at least partially into the intramedullary canal and central bone pocket; wherein the reaming guide assembly comprises a trial stem, a guide tube assembly, and a handle assembly, the trial stem having a proximal end and being configured to fit into the intramedullary canal, the guide tube assembly having 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 being 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;   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; and   driving the cannulated reamer into bone to a predetermined depth, thereby forming a first bone cavity adjacent to the central bone pocket.   
     
     
       19. The method of  claim 18 , further comprising 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. 
     
     
       20. The method of  claim 19 , further comprising 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. 
     
     
       21. The method of  claim 13 , further comprising:
 disengaging a pin located at a distal end of the guide tube assembly from a first notch disposed at a first location about the trial stem;   rotating the guide tube assembly about the trial stem; and   engaging the pin with a second notch disposed at a second location about the trial stem.   
     
     
       22. A method of implanting a tibial prosthesis in a total knee revision arthroplasty, comprising:
 removing a previously implanted tibial prosthesis from a proximal end of a tibia; and   implanting a void filler into the proximal end of the tibia, the proximal end of the tibia having a bone void previously formed by a surgical instrument so as to form a central pocket and lateral and medial pockets blended into the central pocket, the central pocket and lateral and medial pockets having been formed to correspond to a geometry of the void filler so that when the void filler is implanted, a central body of the void filler is received in the central pocket, lateral and medial members of the void filler are respectively received in the lateral and medial pockets, and an opening extending entirely through the central body of the void filler communicates with an intramedullary canal of the tibia, wherein the central body and lateral and medial members each have a curved outer surface that extends about a respective longitudinal axis, the curved outer surface of each of the lateral and medial members tapering inwardly from a proximal end of the void filler to a distal end thereof, the lateral member being integrated into the central body such that the curved outer surfaces of the lateral member and the central body meet at an interface between the lateral member and central body, the interface forms an indented groove that extends in a proximal-distal direction along an entire length of the interface.   
     
     
       23. The method of claim 22, further comprising connecting the void filler to a baseplate component, wherein the void filler is constructed separately from the baseplate component. 
     
     
       24. The method of claim 23, wherein connecting the void filler to the baseplate component includes inserting a stem boss of the baseplate component into the opening extending through the central body of the void filler. 
     
     
       25. The method of claim 23, wherein connecting the void filler to the baseplate component includes inserting a tibial stem through the opening of the central body of the void filler. 
     
     
       26. The method of claim 25, further comprises implanting the baseplate component onto the proximal end of the tibia such that the tibial stem extends from the opening of the central body and into the intramedullary canal and such that the baseplate component engages a proximal end of the void filler. 
     
     
       27. A method of implanting a tibial prosthesis in a total knee revision arthroplasty, comprising:
 removing a previously implanted tibial prosthesis from a tibia;   forming a bone void in the tibia at a proximal end thereof so as to form a central portion and adjacent offset portions of the bone void, the offset portions joining the central portion and tapering inwardly from the proximal end of the tibia toward a distal end thereof, wherein forming at least one of the offset portions of the void includes moving a cutting tool axially along a longitudinal axis into the bone and removing the cutting tool from the bone by moving the cutting tool along the same longitudinal axis, the cutting tool being constrained to movement along the longitudinal axis; and   implanting a void filler and a revision tibial prosthesis onto the proximal end of the tibia such that a central body and adjacent offset members of the void filler are respectively and conformingly disposed in the central and offset portions of the bone void, and such that a stem of the revision tibial prosthesis extends through an opening of the central body and a baseplate component of the revision tibial prosthesis is positioned adjacent a proximal end of the void filler and the proximal end of the tibia, wherein the offset members of the void filler and the central body each define a longitudinal axis about which a respective curved exterior surface thereof extends, the longitudinal axes of the offset members and void filler being offset in a lateral-medial direction.   
     
     
       28. The method of claim 27, further comprising mechanically locking the void filler to the revision tibial prosthesis. 
     
     
       29. The method of claim 27, further comprising inserting bone cement into a gap between the void filler and the tibial prosthesis so as to connect the void filler to the tibial prosthesis. 
     
     
       30. The method of claim 27, further comprising:
 inserting a stem boss of the baseplate component of the tibial prosthesis into the opening of the central body, and   engaging a proximal end of the void filler with the tibial baseplate.   
     
     
       31. The method of claim 27, wherein forming the bone void is performed by an instrument having bone cutting surfaces that correspond to the central body and offset members of the void filler so that a peripheral geometry of the void filler matches surfaces in the tibia created by the instrument. 
     
     
       32. The method of claim 31, wherein the instrument is a reamer assembly. 
     
     
       33. The method of claim 27, wherein the offset members are conically tapered and have a taper greater than a taper of the central portion.