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ABSTRACT CADAVER

Introduction: Historically, soft tissue releases to correct ligament imbalance which can lead to ongoing varus malalignment in total knee arthroplasty are done medially along the tibia. A fixed varus deformity requires medial releasing in order to balance the total knee. We used computer navigation and sequential medial releases to evaluate how much each medial release changed the angular alignment.

Methods: In this study we took four (4) cadaver knees, preformed medial releases in a step-wise fashion: 1) anterior deep medial collateral ligament (mcl); 2) mid-deep mcl; 3) posterior deep mcl; 4) semimembranosus; 5) oblique popliteus ligament; 6) distal capsular release 4cm-6cm below joint line; 7) partial superficial mcl; 8) complete superficial mcl; 9) proximal gastrocnemius; 10) posterior cruciate ligament; 11) distal gastrocnemius. Each release was cycled through a range of motion (ROM) of 0-90 three (3) times with no weigh, .5lbs and 1lbs valgus stresses. The ROM and stress were applied by a series of pullies. A varus/valgus navigation table sampled the alignment at 0 30 45 60 90 degrees.

Results: We saw no significant change in angular alignment until release # 8, complete superficial mcl. The change in alignment in full extension was not as remarkable as the change at 30 degrees to 90 degrees. Each subsequent release (#9, #10, #11) saw an increase in the angular alignment.

Conclusion: We found that there was no significant change in angular alignment until you release the complete mcl and with that the change was substantial. The release of the complete mcl was an all or nothing event because a partial release did not change angular alignment significantly.

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