A tear of the anterior cruciate ligament (ACL) raises the risk of subsequent joint degeneration, the development of osteoarthritis and loss of the meniscus. ACL reconstruction may help prevent these problems but surgery is not required for all patients. However, doctors have found it difficult to identify people with an ACL tear who can opt for non-operative treatment without risking further problems. Now a research team from the Hospital for Special Surgery (HSS) in New York City has published the findings of a study which suggests that knee shape could help decide whether a person needs to have surgery.
Dr Suzanne Maher, associate director of the HSS Department of Biomechanics, said that this was the first study to indicate that the shape of a person´s knee really affects the changes in knee mechanics after an ACL tear. Previous studies had only focused on whether the knee shape raises the likelihood of ACL injury, particularly among athletes.
The HSS researchers experimented with nine knees taken from cadavers, looking to establish how knee shape affected the mechanics of the knee during walking after an ACL rupture. The knees were fitted with sensors and attached to a machine that mimicked walking by applying forces in different directions as it flexed and extended the knees. The researchers found that all knees with ACL tears experienced higher stresses in the back part of the tibial plateau but only some of them had it in the front of the plateau. Dr Maher pointed out that the latter were knees with specific shapes. As she explained, a tibial plateau with a very deep valley and a femur sitting in a deep well indicates a very stable knee. This means that when people with such characteristics suffer an ACL tear, it will not have a substantial effect later on.