Is the popliteus tendon always inserted antero-inferiorly 18.5 mm from the lateral collateral ligament of the femur? Magnetic resonance imaging and cadaveric evaluations

The aim of this study was to analyze the locations of the femoral attachments of the popliteus tendon (PT) and lateral collateral ligament (LCL) via magnetic resonance imaging (MRI) and cadaveric dissection in a Korean population and compare with literature standards to determine whether variability exists. We retrospectively analyzed knee MRIs from 87 cases selected from January 2017 to December 2018. The relationship between the femoral attachment of PT and LCL was analyzed by MRI using PACS and Image J. In addition, the femoral attachments of each structure were identified and marked in 14 unpaired human cadaveric knees. Three-dimensional models were reconstructed, and the surface area, location and distances were analyzed. On MRI, the femoral attachment of PT was located at mean distances of 0.89 mm posterior and 9.35 mm inferior to the LCL femoral attachment. We identified three groups of PT locations relative to the LCL on MRI evaluation: parallel (63%), posterior (29%), and anterior (8%). On cadaveric evaluation, the femoral attachment of the PT was located at mean distances of 0.77 mm posterior and 8.90 mm inferior to the LCL femoral attachment. We also identified three groups of PT locations relative to the LCL on cadaveric evaluation: parallel (43%), posterior (36%), and anterior (21%). Based on both MRI and cadaveric evaluations in a Korean population, the femoral attachment of the PT is located just distal to and posterior to the LCL. The differences between the centroids of the femoral attachments of the two structures was approximately 9.7 mm, suggesting that racially based anatomical differences of the posterolateral corner may exist.