The ACL (anterior cruciate ligament) is in the middle of the knee joint. It connects the thigh and shin bones and helps control back and forth motion while stabilising the knee. ACL reconstruction involves using a graft to help replace a damaged ACL ligament and support knee stability.

An ACL reconstruction is often needed after the ligament suffers significant damage, such as a complete tear.

ACL tears are one of the most common knee injuries and are seen mostly in those who participate in sports that involve considerable twisting of the knee, such as netball or football.

Other causes include sudden stopping, slowing down while running, incorrect landing after jumping and direct contact or strong collision. An ACL tear does not heal and leads to instability of the knee.

Not all ACL tears require surgery. ACL reconstruction surgery is normally recommended for active people who are looking to continue playing their chosen sport and have knee instability. Your surgeon will discuss whether ACL reconstruction is appropriate for you.

ACL reconstruction starts with the surgeon making small incisions around the knee, after which the arthroscope and other equipment are inserted. The ruptured ligament is removed and tunnels are made in the bone of the femur (thigh bone) and tibia (top of the lower leg) to implant the new graft. The graft is taken from either the hamstring tendon or the patella (knee cap) tendon. The graft is prepared to take the form of a new tendon and passed through the holes in the bones.

It is then fixed into the bone and held in place while it naturally heals into the bone, which takes around 3 months. Any other joint damage or issues may be addressed at the same time. The incisions are then closed using sutures and a dressing is applied over the top.

With any joint operation there is the possibility of infection, blood clots (deep vein thrombosis), swelling and bruising and joint stiffness. All precautions are taken to ensure that the likelihood of these occurring is kept to the absolute minimum.

Graft failure due to stretching or rupturing can occur – the rate of failure is approximately 5%. If this does happen, revision surgery is possible using the tendons from the other leg.

Participating in an exercise program before and after surgery with a trained physiotherapist will assist you in achieving the best possible result. You should start physiotherapy as early as possible. Starting physiotherapy before the surgery will better prepare you for recovery after the operation, helping to reduce swelling and making it quicker to regain your range of motion and fully weight bear.

Post operation rehabilitative physiotherapy will include light activities, such as swimming, combined with muscle strengthening exercises. Light jogging can normally start at three months post-surgery and sports can recommence at six months. Most patients find that their full recovery period is closer to 10-12 months post operation.