What it takes to have a high-grade pivot shift—focus on bony morphology

Purpose Variations in femoral and tibial bony morphology have been associated with higher clinical grading and increased quantitative tibial translation, but not tibial acceleration, during the pivot shift test following anterior cruciate ligament (ACL) injury. The purpose of this study was to determine the impact of femoral and tibial bony morphology, including a measurement influenced by both parameters (the Lateral Tibiofemoral Articular Distance (LTAD)), on the degree of quantitative tibial acceleration during the pivot shift test and rates of future ACL injury. Methods All patients who underwent primary ACL reconstruction from 2014 to 2019 by a senior orthopedic surgeon with available quantitative tibial acceleration data were retrospectively reviewed. All patients underwent a pivot shift examination under anesthesia with a triaxial accelerometer. Measurements of femoral and tibial bony morphology were performed by two fellowship-trained orthopedic surgeons using preoperative magnetic resonance imaging and lateral radiographs. Results Fifty-one patients were included at a mean follow-up of 4.4 years. The mean quantitative tibial acceleration during the pivot shift was 13.8 m/s 2 (range: 4.9–52.0 m/s 2 ). A larger Posterior Condylar Offset Ratio ( r = 0.30, p = 0.045), smaller medial-to-lateral width of the medial tibial plateau ( r = − 0.29, p = 0.041), lateral tibial plateau ( r = − 0.28, p = 0.042), and lateral femoral condyle ( r = − 0.29, p = 0.037), and a decreased LTAD ( r = − 0.53, p