The anterior cruciate ligament is the most easily and commonly torn ligament inside the knee and is known as the ACL. This important ligament stops the tibia, the shin bone, from moving forward on the femur, the thigh bone and also controls rotational instability. Many patients who have torn their anterior cruciate ligament can be treated with physiotherapy and exercise to strengthen the muscles that support the knee, therefore, allowing them to compensate for the lack of this ligament.
Patients with severe injuries or continuing instability would be advised to have the ligament reconstructed. Following this surgery, it is very important that the patient undertake an intensive physiotherapy programme. Fortunately, the results of anterior cruciate ligament reconstruction are very good with 90% of patients either returning to full activities or nearly full activities.
ACL Reconstruction Surgery
When the anterior cruciate ligament tears, it is like pulling two horses tails or a rope apart and therefore it is usually almost impossible to stitch the ends of the ligament together and therefore reconstruction of the torn anterior cruciate ligament with a graft is required.
Occasionally, however, the ligament may pull off a piece of bone on the shin in which case this can repair back down and also occasionally the ligament may ping off the femur, the distal thigh bone, and this may allow for a direct repair as well. In most cases though a graft is required.
The operation involves a general anaesthetic, an examination of the knee under anaesthetic to check for all directions of instability, a full diagnostic arthroscopy is carried out to assess for other injuries and these are repaired at the same time eg torn menisci or articular cartilage defects are also dealt with.
A new graft can be obtained by using either hamstring tendons or a part of the patellar tendon utilising small bony blocks at each end. Extremely accurately tunnels are then drilled through the tibia and femur into the knee joint. The aforementioned graft is then threaded through these tunnels and securely fixed at either end using a range of fixation devices. On the femoral side typically a button is used and on the tibial side an interference screw.