Preoperative measurement and analysis of femoral bone canals designed by 3D modelling in lateral extra-articular tenodesis

Abstract

Abstract Background: The anterolateral ligament of the knee joint is an important structure for maintaining rotational stability. Lateral extra-articular tenodesis (LET) has attracted increasing attention. At present, this technique is a hot topic in the study of anterior cruciate ligament revision. Objective: Considering that the design of the LET bone canal is the key to successful surgery, a safe zone of the LET bone canal was created through computer-aided preoperative planning. Methods: Mimics 20.0 was used to conduct three-dimensional modelling of the femur and ACL bone canal. The LET bone canal before surgery was designed by Imageware 13.2. A safe zoom where the bone canal did not overlap with the ACL bone canal, trochlea of the femur, and anterior cartilage of the femoral lateral condyle was used, and the spatial relationship between the safe zoom and the femoral internal condyle was quantified. Results: In all 13 patients, the spherical surface did not overlap with the trochlea of the femur or the anterior cartilage of the lateral condyle of the femur. The sphere overlapped with the ACL canal in 13 patients. The safe zoom was the front of the internal condyle of the femur, and the closest distance from the zoom to the internal condyle of the femur was 9.4802±6.8796 mm. The distance from the medial condyle of the femur to the intersection formed by the line from the most anterior edge of the medial edge of the femoral condyle cartilage surface to the medial condyle and the safety plane was 14.2493±12.1392 mm. The distance from the medial condyle of the femur to the intersection formed by the line from the most inferior edge of the medial edge of the femoral condyle cartilage surface to the femoral condyle and the safety plane was 11.8494±8.7796 mm. In a single case, the shortest distance between the exit needle point and the interface of the safe area was 37.9224 mm. Conclusion: Computer-aided 3D modelling of the preoperative femoral bone canal design of LET can be used to quantify the spatial relationship between the exit needle points and the medial condyle of the femur, accurately plan the route of the LET bone canal, and effectively reduce the probability of LET canal and ACL bone canal overlap.