ACL Reconstruction

Anterior cruciate ligament (ACL) reconstruction is a surgical tissue-graft replacement of the anterior cruciate ligament in the knee, carried out to restore the ligament's function after an injury. It is performed arthroscopically; the torn ligament is usually removed, although in some techniques it is preserved and the graft is passed inside the retained native ligament. Several graft options exist. Autografts use bone or tissue taken from the patient's own body — most commonly an accessory hamstring tendon or part of the patellar ligament, with the quadriceps tendon becoming more widely used. Allografts use tissue from another body, either a cadaver or a live donor. Bridge-enhanced ACL repair uses a bio-engineered scaffold injected with the patient's own blood, and synthetic grafts have also been developed, though little data exists on their strength and reliability. Because autograft tissue is the patient's own, the risk of rejection is minimal, and in young, active individuals the re-tear rate has been shown to be lower with autograft than with allograft. Surgeons have historically regarded patellar tendon grafts as the standard for knee stability. Hamstring autografts have failed at a somewhat higher rate than bone-tendon-bone autografts in a 2017 meta-analysis, but the difference is small enough that both remain viable options; modern fixation methods have reduced the graft slippage and stretching that hamstring grafts historically showed.

Rehabilitation begins with range-of-motion exercises, often guided by a physical therapist, to regain flexibility, limit scar tissue and reduce loss of muscle tone; a continuous passive motion device is sometimes used immediately after surgery. Isometric exercises that place no strain on the knee are the preferred way to prevent muscle loss, and regaining knee extension within two weeks is emphasised in many guidelines. About six weeks is required for the bone to attach to the graft, though patients can usually walk and perform simple tasks before then with caution. Twelve weeks is an important benchmark, after which a more demanding regimen with increasing resistance, and jogging, can begin. More intense activity such as running is generally possible after four months, and light ball work after five months.