Altered knee joint movement after an ACL

Altered knee joint movement after an ACL

Some individuals who have had anterior cruciate reconstruction (ACLR), which is often performed on athletes' knees, may develop early knee osteoarthritis. A new study in theJournal of Orthopedic ResearchIndicates that altered knee joint motion after ACLR may be a factor.

The study used a unique dynamic X-ray imaging system to accurately measure walking in people who had undergone ACLR surgery and those with healthy knees. Compared to healthy controls, ACLR patients had a higher vertical position of the patella and a higher location of joint contact between the patella and the femur. A higher riding patella in the ACLR patients was caused by a longer than normal patellar tendon, with the structure connecting the patella to the tibia. A surprising finding was that a higher patella was observed in both the ACLR knee and the uninjured contralateral knee of the ACLR patients.

The investigators suspect that a taller patella may contribute to the development of knee osteoarthritis by causing the surfaces between the patella and the femur to become unused to loading and leaving previously loaded regions.

We do not know whether a longer than normal patellar tendon was present prior to the ACL injury, resulting in a higher patella or resulting from the ACL injury or ACLR surgery. Further investigation is needed to determine the cause of a longer than normal patellar tendon in individuals who have undergone ACLR surgery. “

Marcus G. Pandy, PhD, Mengsc, corresponding author, University of Melbourne, Australia

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