Tibiofemoral Kinematic Motion Changes After “Pie crusting” of the Medial Collateral Ligament

Introduction: Varus knee deformity is an added complication to total knee replacements that surgeons have to address to achieve balanced ligamentous tension and decrease the need for revision surgeries. Most cases involve osteoarthritis of the knee in which the medial joint space is collapsed when compared to the lateral side. This deformity causes the medial collateral ligament (MCL) to shorten and tighten up in relation to the lateral collateral ligament (LCL) and results in outward bowing of the leg, or a varus knee deformity. The conventional correction method is to lengthen the ligament by standard osteotomy, which involves using a osteotome and releasing the distal attachment of the MCL progressively to eventually balance the joint and in unique cases shortening the LCL ligament. The focus of this study is to address an alternative way to lengthen the MCL to by “pie-crusting,” which is to poke a fixed number of holes in the MCL and study the kinematic motion changes. Methods: Nine cadaveric legs in total were prepped to a rig that allowed the quadriceps, biceps femoris and semimembranosus muscles to be put under weighted tension and permitted free range of motion. The knee was cycled through the rig three times for each experimental condition and a Polhemus tracking system was used to record changes in real time allowing bio-kinematic analysis of the motion and changes in gap length. Experimental conditions included: a no punctures made, control, and three stages of hole punctures in the MCL in increasing density patterns. Results: Preliminary Data results still under investigation. Discussion and Conclusion: We predict that creating micro cuts into the ligament would provide the necessary adjustments to achieve balanced ligamentous tension of the knee in a more controlled fashion vs the traditional osteotome method of lengthening. This technique could serve as a more precise and predictable way to achieve the ligamentous laxity desired in total knee replacements with various deformities.