Written by Dr Alexey Borshch, Orthopaedics, FAOrthA, MBBS, BSc(Hons), dralexeyborshch.com.au on 30 October 2026
The anterior cruciate ligament (ACL) is one of the main stabilising ligaments in the centre of the knee. It helps prevent the shin bone (tibia) from moving excessively forward on the thigh bone (femur) or rotating excessively as the knee pivots. A torn ACL usually does not heal back together, so an ACL reconstruction replaces it with a new ligament made from a tendon graft. The operation is usually done under a general anaesthetic, often with local anaesthetic or a nerve block for pain relief afterwards. It is performed arthroscopically (keyhole surgery), with a small camera inserted through small incisions at the front of the knee as well as incisions for the harvesting and placement of the graft. The ACL, menisci, cartilage and other ligaments are checked first, and associated injuries can be treated in the same operation. The graft is usually taken from your own hamstring, quadriceps or patellar tendon. The choice depends on your age, sport, work, kneeling needs, previous surgery and anatomy, and is discussed with you before surgery. Small tunnels are drilled in the shin bone (tibia) and thigh bone (femur) at the original attachment points of the ACL. The graft is passed through the tunnels and held with fixation devices, and its position and tension are checked before the wounds are closed and dressed. In selected knees, an additional procedure on the outside of the knee (lateral extra-articular tenodesis, or LET) may be added to help control rotation. Afterwards, crutches are usually used for a short time, and a staged physiotherapy program begins, starting with settling the swelling and regaining full straightening of the knee. With time, the replaced ligament becomes incorporated into the bone and receives its own blood supply, becoming nearly as strong as the original ACL.