Background: In lateral unicompartmental knee arthroplasty (UKA), a sagittal cut is often performed through the patellar tendon (PT). Although the approach is likely widely used, it has not been described in detail, especially regarding the site of the split. This study aimed to clarify where the split should be made.
Methods: This single-center retrospective cohort study included 49 consecutive patients and 51 knees with lateral osteoarthritis. Using preoperative computed tomography, we measured the distance from the medial edge of the PT to the intersection of the PT and the sagittal cutting line, defined as a line parallel to the Akagi's line and passing the tip of the lateral tibial spine.
Results: The sagittal cut line passed a mean of 45 ± 11% of the patellar tendon width from the PT medial edge.
Conclusions: The tendon split should be made just medial to the center of the PT because it is where the sagittal cut line for lateral UKA passes.
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