Apparatus for knee surgery and method of use

Abstract

The present invention comprises a set of instruments and a method for their use in preparing a knee joint to receive knee implants. The inventive instruments and method are generally suitable for knee joint surgery. Furthermore, they include features that make them suitable for performing a minimally invasive knee surgery in which a smaller than normal incision is made and oriented to preserve the quadriceps mechanism and protect the suprapatellar pouch. The instruments permit switching from a minimally invasive technique to a standard open technique at any point in the procedure. An illustrative set of instruments for total knee arthroplasty and an associated minimally invasive technique are described.

1 - 51 . (canceled) 
     
     
         52 . A guide for establishing a position reference on a distal portion of a femur having a distal end, an anterior surface, a medial side surface, a lateral side surface, posterior condyles, and anatomic landmarks, the guide comprising:
 a base having a reference surface for engaging said distal end; and   a pin guide mounted for rotation relative to the base, the pin guide including at least one pin guide hole for guiding a reference pin to engage one of said medial and lateral side surfaces of said distal femur.   
     
     
         53 . The guide of  claim 52  wherein the pin guide has an alignment portion for aligning with anatomic landmarks on said distal femur. 
     
     
         54 . The guide of  claim 53  further comprising a foot connected to the base, the foot extending at an angle from the reference surface to engage said posterior condyles to establish a posterior size reference. 
     
     
         55 . The guide of  claim 54  further comprising a plate, the plate rotationally mounted to the base and the pin guide mounted on the plate so that as the pin guide rotates relative to the base the pin guide also rotates relative to the base. 
     
     
         56 . The guide of  claim 55  wherein the base includes a plurality of rotational alignment holes and the plate includes a plurality of alignment holes, different pairs of holes aligning at different angles of rotation between the base and plate. 
     
     
         57 . The guide of  claim 56  wherein the pin guide is mounted for translation relative to the plate so that the plate can be rotated to set the rotation of the pin guide hole relative to the base and the pin guide can be translated relative to the plate to set the spacing of the pin guide hole from the base. 
     
     
         58 . The guide of  claim 57  further including an anterior probe mounted for translation relative to the plate, the anterior probe having a probe tip for engaging said femoral anterior surface, the probe having size indicia to indicate the distance the probe is translated relative to the plate. 
     
     
         59 . The guide of  claim 58  further including a feeler gauge that indexes the translation of the pin guide relative to the plate to the translation of the probe relative to the plate so that sizing information determined by the probe is reflected in the position of the pin guide. 
     
     
         60 . The guide of  claim 59  wherein the pin guide is mounted for mediolateral translation relative to the plate so that it can be moved to a position adjacent the side of the femur. 
     
     
         61 . A guide for establishing a position reference on a distal portion of a femur having a distal end, an anterior surface, a posterior surface, a medial side surface, a lateral side surface, posterior condyles, a femoral axis, and anatomic landmarks, the guide comprising:
 means for establishing a desired rotation angle relative to said femoral axis; and   means for establishing a desired A/P position between said anterior and posterior surfaces of said femur; and   means for establishing a datum on said distal femur that records the rotation angle and A/P position in such a way that the datum can be subsequently referenced by bone cutting guides to produce bone cuts relative to the rotation and position information.   
     
     
         62 . The guide of  claim 61  wherein the datum comprises an element selected from the group consisting of a pin, a hole, a slot, and a notch. 
     
     
         63 . The guide of  claim 61  wherein the datum is able to be referenced by subsequent instruments to establish the varus-valgus angle, external rotation, and anteroposterior position of bone cuts. 
     
     
         64 . The guide of  claim 61  wherein the means for establishing a desired rotation angle comprises a base having a reference surface for engaging said distal end of said femur and a datum guide mounted for rotation relative to the base, the datum guiding the positioning of a datum on one of said medial and lateral side surfaces of said distal femur. 
     
     
         65 . A method for establishing a position reference datum on a distal portion of a femur having an anterior surface, a posterior surface, posterior condyles, a femoral axis, medial and lateral epicondyles, and an A/P axis, the method comprising the steps of:
 determining a desired rotation angle relative to the femoral axis;   determining a desired A/P position between the anterior and posterior surfaces of the femur;   creating a datum on the distal femur that records the rotation angle and A/P position in such a way that the datum can be subsequently referenced by bone cutting guides to produce bone cuts relative to the rotation and position information.   
     
     
         66 . The method of  claim 65  wherein the step of determining a desired rotation angle is accomplished by aligning a datum guide relative to an anatomic reference selected from the group consisting of the femoral posterior condyles, a line drawn between the medial and lateral femoral epicondyles, and a line drawn along the distal femoral A/P axis. 
     
     
         67 . The method of  claim 65  wherein the step of determining a desired A/P position comprises contacting the anterior femoral surface with a probe. 
     
     
         68 . The method of  claim 65  wherein the step of creating a datum comprises a step selected from the group consisting of drilling at least one hole, cutting at least one slot, and setting at least one pin in the femur. 
     
     
         69 . The method of  claim 65  further comprising the steps of:
 providing a pin guide; 
 establishing the rotation by aligning the pin guide with one of the femoral posterior condyles, a line drawn between medial and lateral epicondyles, and a line drawn along the A/P axis; 
 establishing the A/P position by offsetting the pin guide from a probe in contact with the anterior surface; and 
 establishing the datum by guiding at least one pin through the pin guide and into the femur. 
 
     
     
         70 . The method of  claim 69  wherein the step of establishing the datum comprises guiding at least two pins through the pin guide and into the femur. 
     
     
         71 . The method of  claim 65  further comprising the steps of:
 referencing the datum with a cut guide to orient the cut guide relative to the rotation angle and A/P position; and 
 guiding a cutter with the cut guide to cut the femur. 
 
     
     
         72 . The method of  claim 71  further comprising the step of making an incision on the at least one of the medial and lateral sides of a knee to expose the femur from the side and performing the other steps through the incision from the side of the knee. 
     
     
         73 . A method for establishing a position reference datum on a distal portion of a femur having a distal end, an anterior surface, a posterior surface, a medial side surface, a lateral side surface, posterior condyles, a femoral axis, and anatomic landmarks, the method comprising the steps of:
 providing a guide having a base and a pin guide mounted for rotation and translation relative to the base;   placing the base against the distal end of said femur;   rotating the pin guide relative to the base to a desired rotation angle;   translating the pin guide relative to the base to a desired A/P position; and   inserting at least one pin into said femur with the pin guide, the at least on pin fixing the rotation angle and A/P position for future reference.   
     
     
         74 . The method of  claim 73  wherein the step of inserting at least one pin comprises inserting at least two pins. 
     
     
         75 . The method of  claim 73  further comprising the steps of:
 mounting a cut guide on the pin to orient the cut guide at the desired rotation angle and A/P position; and 
 guiding a cutter with the cut guide to make anterior, posterior and chamfer cuts on the distal femur. 
 
     
     
         76 . The method of  claim 75  further comprising the steps of:
 making an incision on one of the medial and lateral sides of the knee to expose the femur from the side; and 
 performing the other steps through the incision from the side of the knee. 
 
     
     
         77 - 114 . (canceled)