A key stabilising ligament inside the knee, commonly injured in sport.
The ACL is one of the two cruciate ligaments crossing inside the knee joint, running from the back of the femur to the front of the tibia. Its main job is to resist anterior translation of the tibia relative to the femur and to limit rotational movement, giving the knee rotational and translational stability during pivoting.
ACL tears are common in cutting, pivoting and landing sports and are a major driver of time away from sport, surgical decision-making, and long-term joint health conversations, including future osteoarthritis risk. Whether to manage a tear operatively or non-operatively, and when an athlete is ready to return, are central decisions that shape the whole rehab pathway and the clinician-patient conversation about risk.
Clinically it is assessed with tests such as the Lachman test, anterior drawer and pivot shift, alongside MRI to confirm tear and check for associated meniscal or chondral damage. Rehabilitation progress and return-to-sport readiness are tracked through progressive strength testing, limb symmetry on hop tests, and increasingly through validated psychological readiness measures alongside time from surgery.
No single hop test or strength ratio guarantees safe return to sport, and relying on one measure in isolation, or on time since surgery alone, overstates readiness and understates reinjury risk. Limb symmetry indices can also be misleading if the uninjured limb has itself detrained, masking a true deficit.