ACL reconstruction

What is involved?

An anterior cruciate ligament (ACL) reconstruction is a procedure whereby a donor graft is placed within the knee and secured to the femur and tibia within sockets or tunnels providing stability to a previously unstable knee.


The first stage is to examine the knee whilst the patient is under anaesthetic to ensure that the knee is indeed unstable due to a deficient ACL.  Once this is confirmed preparation of the donor graft commences.  There are many options available when considering graft choice all of which have pros and cons.  Some of the most common options used are hamstring tendon, quadriceps tendon, patella tendon with bone blocks on either side, and allograft tendon (cadaveric donor tissue that has been sterilised and pre-prepared).  Each of these grafts can be created and used in different ways to ensure stability of the knee and a decision on which graft choice one should you use is based entirely on the individual patient circumstances including the type of injury they have, the activities they wish to return to, and other patient specific factors.  It is advisable to discuss with your treating surgeon which graft choice he or she feels is most appropriate for you.


The main part of the operation is carried out arthroscopically (keyhole) and once the graft is ready, and its size has been determined, sockets or tunnels are drilled using specific instruments to ensure the graft is positioned in an anatomical fashion replicating where the old anterior cruciate ligament used to sit.  The graft is then secured in place, again using a variety of methods that will be patient and surgeon dependent.  The knee is then checked for stability and the wounds are closed, normally with dissolving sutures. 


Why might I need an ACL reconstruction?

The anterior cruciate ligament is one of the main stabilising structures in the knee joint and is often ruptured or torn as part of a twisting or hyperextension injury to the knee.  This is often sports related such as football, netball or skiing.  In some circumstances the knee will be grossly unstable and if you wish to return to a high level of activity this may mean you require reconstruction of your anterior cruciate ligament to prevent the knee giving way during sporting or day to day activities.  On other occasions the knee will feel reasonably stable on a day to day basis and your treating doctor may encourage you to pursue initially a non-operative course to try and rehabilitate and stabilise the leg with physiotherapy.  If non-operative approaches fail and you have an ongoing lack of trust or instability in the knee doing activities you wish to do then your surgeon may recommend an anterior cruciate ligament reconstruction. 


What happens after surgery?

The operation is normally carried out under general anaesthesia with local anaesthetic and potentially nerve blocks around the knee to try and help with post-operative pain management.  Immediately following the procedure you will have dressings on the knee and a special cooling knee cuff to reduce swelling and post-operative pain.  Our expert physiotherapy teams will visit you once you have recovered from the anaesthetic and get you up and walking a few hours after your surgery.  It is important to encourage early mobilisation and weight bearing to reduce the risk of venous thromboembolism and improve the muscle rehabilitation following surgery.  Once the physiotherapy team are happy with your mobility, your pain is under control and you are fully recovered from the anaesthetic, you will be able to be discharged home.  Anterior cruciate ligament reconstruction is often carried out as a day case procedure but occasionally patients will stay overnight to allow them to have further physiotherapy or pain medication as required.  After you are discharged the office will organise an appointment with you at approximately 2 weeks post-operatively to remove the dressings, check the wounds and the range of movement in your knee.  You will then have regular follow ups at appropriate time points in order to ensure you are hitting the recovery milestones expected.


Recovery milestones

Week 1 – 2

It is important over this period of time to rest the knee, elevate the leg to allow the swelling to reduce, take regular pain killers and anti-inflammatories and continue regular ice therapy.  This allows the swelling or effusion within your knee to settle and as the pain improves you will gradually be able to work on re-gaining your range of movement.  It is also important in the first 2 weeks to perform some static quads exercises in an attempt to prevent the quadriceps muscle from disengaging and wasting away.  We would recommend that you seek advice from a physiotherapist within the first 2 weeks of your surgery in order to commence your rehabilitation protocol. 


Weeks 2 – 4

Over this period you should continue to use ice therapy and compression techniques as required to reduce the swelling.  You will also be encouraged to increase to full weight bearing, to perform exercises to improve patella mobility and facilitate increased muscle tone and control.  Once your wounds have healed we will also encourage you to get in a pool and do some hydrotherapy and also to engage with a static bike in order to improve your range of movement and leg strength.


Weeks 4 – 12

Over this period of time the pain should fully subside with activities of daily living.  The range of movement of the knee should return to near normal, the swelling should completely resolve and your gait pattern should return to normal.  You will also be encouraged by your physiotherapist to do exercises to improve the strength and tone of your muscles and also to improve your proprioception. 


Weeks 12 – 24

Over this period of time the goals will be to maximise the tone and power in your core and lower limb musculature.  You will progress to sports specific plyometric proprioceptive and change of direction exercises to maximise your neuromuscular control and to increase your running speed.  The aim is to return to contact or change of direction sports at approximately 9 months post-operatively.  Prior to this, regardless of how well you have rehabilitated in terms of neuromuscular control and power the blood supply to the graft is not yet fully established and therefore there is potential weakness to re-injury.


The timeline above is approximate.  We no longer follow a time based protocol for anterior cruciate ligament reconstruction but a goal based approach.  The full ACL rehabilitation protocol is available under the One. Journey section of this website. 


Frequently asked questions 

  1. Do I need an anterior cruciate ligament reconstruction?

    Whether or not someone requires an ACL reconstruction is highly variable.  There are pros and cons to operative and non-operative approaches to anterior cruciate ligament ruptures.  It is advisable to discuss with your treating physician or surgeon what the best option for you is bearing in mind the severity of your injury, the implication your specific injury has had on your knee stability, the activities you wish to return to and any other medical conditions you may have. 

  2. Which graft will you use?

    There are multiple graft options including allografts and autografts.  Autografts can be taken from various other locations within your body.  There are pros and cons to each graft choice.  The key thing is that your treating surgeon has a selection of graft choices at his disposable to perform a bespoke procedure for your specific knee.  Please feel free to ask your treating doctor which graft they feel is best for you.

  3. How long until I can drive?

    This is somewhat dependent on whether it is your left or right leg being operated on and whether or not you have an automatic or manual car.  On average, if your right leg is the involved side you will not be able to drive for between 4-6 weeks post-operatively.  It is advisable you consult your insurance company to ensure they have no further restrictions.

  4. How long until I can run?

    This is variable and fairly patient specific.  The key thing is before you commence impact activities such as running you have good neuromuscular control and proprioception to prevent any instability in the stance phase of your gait cycle.  Your surgeon or treating physiotherapist will be best placed to advise you as to when this may be.  On average one can normally get back to running somewhere between 3-6 months post-operatively. 

  5. When can I ski?

    We would normally recommend not skiing for 9 months post-surgery as a minimum.

  6. When can I return to sport?

    Non-contact or twisting sports such as cycling, swimming (not breast stroke), and jogging can be returned to somewhere between 3-6 months post-operatively.  Contact sports or sports that involve significant change in direction should not be commenced until a minimum of 9 months post-operatively.

  7. What is the chance of re-injuring my anterior cruciate ligament?

    The literature would support a re-rupture rate of anterior cruciate ligament reconstructions somewhere up to 10%.  Modern techniques are likely to mean that this risk is reducing however it is important to note that if you return to activities that put stress on the knee there is a chance that re-injuring your knee.

  8. Will my graft harvest have an impact on my activity?

    Dependent on where the graft is taken from in your particular case, it will have some minor impact on the function of that tendon post-operatively.  This is not normally however perceivable on a day to day basis and only noticeable when specific scientific testing has been done to patients post-operatively.

  9. Am I more likely to get arthritis following ACL reconstruction?

Evidence shows that patients who have ruptured their anterior cruciate ligament are more likely to develop arthritis in later years than those who have not ruptured their anterior cruciate ligament.  There is no strong evidence to suggest that having an anterior cruciate ligament reconstruction either increases or reduces these risks.  However if your knee remains unstable following an ACL rupture and nothing is done to stabilise the knee, further damage to the articular or meniscal cartilages is likely and this will increase the risk of arthritis in the future.


Patient Information for Consent - ACL reconstruction