Femoral Condylar Geometry Is Related to MCL Force During Knee Flexion in Cruciate Retaining Total Knee Arthroplasty

Description

During this presentation from the ISTA 2024 conference held in Nashville, Cynthia Kahlenberg, a hip and knee arthroplasty surgeon at HSS, introduces her talk on the factors influencing patient satisfaction following total knee arthroplasty (TKA). She acknowledges Zimmer Biomet's contribution of implants and discusses the high rate of dissatisfaction among TKA patients due to perceived knee instability, particularly in mid-flexion. Kahlenberg highlights the roles of key stabilizing structures—the anterior cruciate ligament and medial meniscus—typically resected during the procedure, leading to increased reliance on the medial collateral ligament (MCL) for joint stability. She presents findings from a cadaveric study revealing a correlation between MCL tension at 30 degrees of flexion and anterior tibial translation, emphasizing the importance of MCL balance for mid-flexion stability. The talk details various techniques for achieving proper MCL tension, focusing on femoral component positioning and anatomy. Kahlenberg articulates her study's objective to assess MCL force during flexion in cruciate-retaining total knees, using a physics-based computational model to analyze how MCL ratio—affected by surgical decisions—relates to the flexion angle at which the MCL begins to engage. The results demonstrate that knees with larger MCL ratios engaged the MCL at lower flexion angles, impacting the force distribution during flexion. Ultimately, she concludes that procedure modifications affecting MCL ratios significantly influence MCL force in flexion, paving the way for ongoing research on optimizing MCL force and evaluating insert design impacts.

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