The decision to proceed to ACL surgery is reached after a careful history, examination and interpretation of the MRI investigations and a discussion with the patient.  High level athletes and elite sportspeople require surgery to get back to playing sport at their previous pre-injury level.  Non-elite athletes and normal people who have sustained an ACL injury should consider whether they would like to undergo surgery to restore stability to their knee but not everyone requires an ACL reconstruction to have stability.  A small proportion of patients can regain knee stability with physiotherapy alone.  This depends on a number of factors and these are best discussed with your consultant knee surgeon. 

In some individuals, despite physiotherapy, the knee carries on giving way even when walking and therefore surgery becomes essential.  In other patients walking and running in a straight line is okay but any twisting or turning results in the giving way of the knee and if the patient requires this level of function, then an ACL reconstruction is recommended.  Some individuals have manual jobs which are very strenuous and require complete knee stability and therefore for these individuals an ACL reconstruction is also recommended.

For individuals with high levels of function and demands from their knee (professional sports people and high functioning non-professionals), an ACL reconstruction is usually required to regain knee stability.

ACL reconstruction surgery is a complex operation which is designed to restore stability to the human knee.  When an ACL ruptures, a lot of force goes through the knee and it is very unusual for an ACL to be ruptured in isolation.  The ACL becomes injured along with other anatomical structures within the knee which help to provide stability.  It is imperative that a proper assessment is carried out by a specialised knee surgeon and an appropriate plan made for the surgery.

Other pathologies, like meniscal tears, root tears and ramp lesions must be addressed to ensure a good outcome and minimise the risk of re-injury and re-rupture, which can be disastrous for patients.

The surgery is carried out under general anaesthesia where the patient is asleep.  Sometimes a nerve block is also carried out to provide good pain relief following the operation.  The operation is carried out arthroscopically (keyhole surgery). 

The knee joint is thoroughly assessed during surgery.  The torn anterior cruciate ligament must be replaced by new tissue.  A discussion around what type of tissue would be best suited to each individual will take place preoperatively. 

The options around the tissue are an autograft which is the patient’s own tissue.  This can be hamstrings, patellar tendon or a newer technique using the quadriceps tendon (please see below around graft selection).  The tissue is harvested from the donor site taking care not to injure any other structures.  Tunnels and sockets are drilled within the tibia and femur and once the graft is prepared it is placed in the anatomical position and tensioned to ensure that the graft performs its function appropriately.  At the same time if any other tissues need to be repaired, for example meniscal tears or ramp lesions (please see section on meniscal surgery), these will be carried out at the same time to restore stability to the knee and minimise any risk of further instability and re-ruptures of the graft. 

The length of surgery depends on the complexity of the operation.  If it is an anterior cruciate ligament reconstruction alone with no other injuries, this can be achieved in around an hour.  If other structures require repair then the operation can take longer than sixty minutes, up to around two hours. 

The aim of ACL reconstruction surgery is to restore stability to the knee joint whilst retaining a full range of movement and allowing the patient to get back to high levels of pre-injury activity and sport. 

The success rate of ACL surgery is generally very good in the literature.  This depends on the surgeon, the surgical technique and the type of graft used.  The overall aim is to restore function and reduce the risks of re-rupture of the graft.