The Lateral Malleolus Is a Simple and Reliable Landmark that Can Be Used to Reliably Perform Restricted Kinematically Aligned Total Knee Arthroplasty—Anatomical and Clinical Studies in Japanese Population

Abstract

In restricted kinematic alignment total knee arthroplasty, bone resection is performed to within a safe range to help protect against failure from extreme alignments. Patient-specific instrumentation, navigations and robotics, are often required for restricting bone cuts to within a specified safe zone. We hypothesized that the lateral malleolus could be used as a landmark for restricting the tibial osteotomy using a mechanical jig. Here, we examine its feasibility in anatomical and clinical settings. We studied long-leg standing radiographs of 114 consecutive patients (228 knees) who underwent knee arthroplasty in our institution. We measured the lateral malleolus angle, the angle between the tibial axis and the line between the centre of the knee and the lateral surface of the lateral malleolus. The medial proximal tibial angle was also measured before and after restricted kinematic alignment total knee arthroplasty under restriction with reference to the lateral malleolus. Mean lateral malleolus angle was 5.5° ± 0.5°. This was relatively consistent and independent of patient height, weight and BMI. The lateral malleolus is a reliable bone landmark that can be used to recognize approximately 5.5° of varus intraoperatively. A surgeon can use this as a restriction of the tibial varus cut up to 6° without the requirement for expensive assistive technologies. Received: 26 July 2022 Accepted after revision: 18 October 2022 Accepted Manuscript online: 21 October 2022 © . Thieme. All rights reserved. Georg Thieme Verlag KG Rüdigerstraße 14, 70469 Stuttgart, Germany