ACL Reconstruction

What is this procedure?

Tears in the anterior cruciate ligament cannot be repaired, so the torn ACL needs to be removed and reconstructed. It is replaced with a piece of tendon, either taken from the hamstrings at the back of the knee or the patella tendon from the front of the knee. This is known as an autologous graft (i.e. the tissue used for the graft is taken from you). An alternative to using hamstrings tendon is to use patellar tendon (in this case the graft is taken from just below the kneecap). Both offer good results with no reported difference in failure rates. Choice is largely directed by surgeon preference.

The procedure is done arthroscopically through small incisions (as described in the previous section) to allow precise graft positioning whilst minimizing the stiffness and scarring. Depending on the type of graft used, additional incisions may also be necessary to take the graft and secure it in place.

Who should consider this operation?

Surgery is recommended if you experience symptoms of instability in your knee after a tear to the ACL. In particular, if you are an active individual who aims to return to sport, you are likely to benefit from reconstruction of the ACL. However, cases should be assessed individually taking into account factors discussed earlier including age, occupation and expectations.

Preoperative preparation and evaluation

Rehabilitation following an ACL rupture begins before surgery is undertaken. If you are awaiting an ACL repair you should be instructed by your physiotherapist on pre-operative measures to reduce pain, swelling and inflammation, and maximize range of movement and muscle strength. This helps to ensure the best possible results post-operatively. This pre-operative period is often called ‘prehabilitation’ and during this time the therapist will also be used to explain thoroughly what you should expect postoperatively. The protocol should be explained and realistic goals set between the surgeon, physiotherapist and yourself. These goals should be timed and take into consideration various factors including your sporting activities, the type of surgery performed and the surgeon’s preferences.

What happens in the postoperative period?

ACL reconstruction is generally performed as a day case procedure or with one night hospital stay, although this depends to some extent on the time of day that the surgery is performed and the effects of the anaesthetic on the individual. You will be provided with crutches to use as required for comfort after surgery. The crutches can be discarded as soon as you can lift your leg up in a straight position and fully weight bear. Instructions on how to progress with crutches will be given by the physiotherapist. Ice, simple analgesia and anti-inflammatory medications are advised to help manage pain and swelling and to ensure full weight bearing status is achieved as early as possible. These treatments should be used as directed by the surgeon.

You will be seen before discharge from hospital by the physiotherapist and will be followed up regularly as you progress through a rehabilitation programme. The average rehabilitation time following ACL reconstruction is 6-9 months, although this varies from individual to individual and depends on the presence of any coexisting injuries. The rehabilitation programme will progress through phases. Initially the emphasis will be on obtaining full range of movement, especially straightening the knee fully and reduction of swelling. Later there will be an increased emphasis on strengthening, proprioception and core stability. Finally sport specific drills of varying intensity will be introduced. It is important that you do not progress through the programme faster than instructed by the surgeon and physiotherapist as this risks injury and graft failure. An example of an ACL rehabilitation programme can be found on the physiotherapy section of this website.

ACL revision

Graft failure following primary ACL reconstruction is reported at approximately 3-6%, with the greatest risk being in the first year post operatively. The most common cause of graft failure is trauma, with technical errors and infection collectively accounting for less than 8% of primary ACL reconstruction failures. Revision of ACL graft will usually use a different graft type, typically a patella tendon graft. Following a revision ACL reconstruction there is a similar rehabilitation programme to primary ACL repairs although more time may be required.