Articular contact was 7.6 mm higher on femoral trochlea in ACLR, contralateral knees due to 8.9-mm longer patellar tendon
By Elana Gotkine HealthDay Reporter
TUESDAY, March 25, 2025 (HealthDay News) — In anterior cruciate ligament reconstruction (ACLR) and uninjured contralateral knees, the patella articulates higher on the femoral trochlea due primarily to a longer patellar tendon compared with healthy knees, according to a study published online March 19 in the Journal of Orthopaedic Research.
Marcus G. Pandy, Ph.D., from the University of Melbourne in Australia, and colleagues measured six‐degree‐of‐freedom patellofemoral and tibiofemoral motion in ACLR and uninjured contralateral knees during gait and compared the results to healthy knees. Six‐degree‐of‐freedom patellofemoral and tibiofemoral motion was measured in 15 ACLR participants and 10 healthy individuals for complete cycles of level walking and downhill walking.
The researchers found that compared with controls, mean patellar superior translation, anterior translation, and flexion over the gait cycle were 4.4 to 5.6 mm greater, 5.4 to 6.3 mm greater, and 3.7 to 7.0 degrees less, respectively, in the ACLR and contralateral knees across both activities. In the ACLR and contralateral knees versus controls, articular contact was 7.6 mm higher on the femoral trochlea. The patellar tendon was 8.9 mm longer in the ACLR and contralateral knees versus controls. Fourteen of 30 knees among ACLR participants had an Insall-Salvati ratio ≥1.20, indicating patella alta. Compared with controls, mean tibial external rotation and anterior translation over the gait cycle were 3.4 to 3.8 degrees greater and 2.6 to 3.0 mm greater in the ACLR knees across both walking and downhill walking.
“A higher riding patella may contribute to the development of patellofemoral osteoarthritis by shifting the load‐bearing areas on the femoral trochlea to regions of cartilage unaccustomed to load and leaving previously loaded regions underloaded,” the authors write.
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