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The anterior cruciate ligament (ACL) is a ligament in the middle of your knee that connects the front of your shin bone to the back of your thigh bone and helps to stabilise the knee . Tears (or ruptures) to this ligament can occur when making sharp twists and turns, causing the knee to ‘give way’ or collapse. This is commonly as a result of an injury whilst skiing, or a sporting injury. An ACL reconstruction replaces the ligament with a piece of suitable tissue from elsewhere in your body (an autograft) or from a donor (allograft).

ACL repair versus reconstruction: which is right for me?

While ACL reconstruction, replacing the damaged ligament completely, has long been the traditional treatment for ACL injuries, ACL repair is a relatively new procedure which involves keeping the existing ligament in place to promote self-healing, working to speed up recovery time. This would be particularly beneficial for those patients with more minor or partial tears, younger patients or those with newer injuries. However, your surgeon will present both options and weigh up which would be best for you.


If you do not lead an active life and your knee feels stable during usual activities in daily life, you may be able to manage your ACL injury without surgery. However, non-surgical treatments are usually reserved for minor tears or lower demand i.e. non sporting patients.


How to tell if you need ACL reconstruction

An ACL rupture happens as a result of a twisting injury to the knee. The common causes are football, netball, rugby and skiing injuries. You can injure other parts of your knee at the same time, such as tearing a cartilage or damaging the joint surface.

You may hear a popping sound at the point of injury and your knee will feel unstable and ‘give way’. The knee usually swells quite quickly due to bleeding inside the knee. Your range of movement may be affected as well, with certain movements becoming difficult or impossible.

How soon should you get ACL reconstruction surgery?

You should consult doctors as soon as you injure your knee, as they can confirm your injury, and discuss your options with you. They can refer you to a physiotherapist to prepare your knee for surgery. Should you decide that surgery is right for you, the sooner you have surgery, the better, as delaying surgery may result in additional damage within your knee with every subsequent episode of your knee giving way, which may necessitate more extensive surgery and your recovery becoming more complicated. It may also affect the likelihood of reinjuring your ACL after surgery.

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Preparing for ACL reconstruction surgery

Rehabilitation before surgery

Before any treatment can be considered, you must get your knee ‘settled’. This means ensuring swelling has resolved and regaining a full range of movement in the joint. On occasion, associated injuries in the knee may prevent your knee settling down, and you may require surgery to rectify this before you can proceed to ACL reconstruction.

To aid recovery, you will be asked to ensure your thigh and hamstring muscles are as strong as possible before having surgery, and you may be referred for physiotherapy to do this. The physiotherapist will provide a programme of stretching and strengthening to settle your knee down, restore movement, and build strength to prepare you for surgery. This is commonly called ACL prehabilitation, and by completing this programme, you can expect to be ready for surgery in 3-6 weeks after your injury.

Preparing for surgery

Make sure you are fully prepared for your procedure before going into hospital. You should discuss any concerns or questions with your consultant prior to admission for surgery so you are satisfied with the plan for your surgery. On occasion your surgeon may not be able to give an exact plan as it may depend on what they find once they start the operation, either by looking inside the knee, or examining your knee once you are anaesthetised.hey will explain this to you before starting the operation.

It’s also a good idea to be prepared for after leaving hospital. You are likely to be using crutches, so arrange for a friend or family member to take you home and for someone to help you at home for 1-2 weeks, as getting around might be difficult.

What happens during an ACL reconstruction?

ACL reconstruction surgery is usually performed under general anaesthetic and your surgeon will make one or more cuts on the front and sides of your knee. Some surgeons perform the operation by arthroscopy (‘keyhole’ surgery) using a camera to see inside the knee. Your surgeon will replace the ACL with a piece of suitable tissue (a graft) from elsewhere in your body (this is an ‘autograft’) usually hamstring tendons, though kneecap (patellar) tendon, thigh (quadriceps) tendon or donor graft (allograft)can be used). The top and bottom ends of the replacement ligament are fixed with special screws or anchors into ‘tunnels’ drilled in the bone.

How long does an ACL reconstruction take?

The operation usually takes between an hour and an hour and a half.

Recovering from ACL reconstruction

How long does it take to walk after ACL reconstruction?

Immediately after your surgery, you will be given light exercises that you can start in hospital and continue at home. These will help you back on to your feet, and you will be given crutches to help you.

You can expect to need crutches for around 1-2 weeks before you will be able to walk unaided, but you should only do this when you feel confident to do so.

Recovery time

Most people make a good recovery from ACL repair surgery and return to normal activities within around 9-12 months. You will be given a structured rehabilitation schedule to follow which will be split into phases.

Of course, recovery times will vary from person to person.

Phase 1:

You should be able to go home the same day after your surgery. The first phase of recovery will be similar to your pre-surgery preparation and aim to dispel any swelling around the knee as well as regain range of movement and strength of the muscles around the knee joint. You will also be given crutches to help with getting around to begin with.

This is likely to take between 4 and 8 weeks.

Phase 2:

The second phase of recovery has the aim to return to light exercise and sporting activities. Your surgeon and physiotherapist may suggest limiting bending your knee to around 90 degrees in this phase, so activities such as stationary bikes or swimming, to limit any twisting and turning for the knee, will be advised.

This phase will take between 8 weeks to six months.

Phase 3:

The final phase of treatment will look to get you back to the levels of exercise and sport you were at before your injury, by gradually introducing twisting and turning back into your activities.

Depending on the level of sport you take part in, this will normally take 9 months. It may also take you longer to regain confidence in your knee, so only participate in activities when you feel comfortable, and when your recovery team is happy with your progress.

Pain during recovery

As with any surgery, there may be some pain when you are recovering. You may experience some bruising, swelling and discomfort in the knee joint after your treatment, but this can be managed with painkillers. These symptoms are likely to last for around 1-2 weeks after surgery.

You may experience stiffness and swelling from time to time throughout your recovery, however this will lessen as time goes by. If the symptoms are persistent, contact your doctor who will be able to advise the best course of action.

Potential complications of ACL reconstruction

As with any surgery, there can be complications. General complications can be:

  • Pain
  • Bleeding
  • Infection in the surgical wound
  • Unsightly scarring
  • Blood clots (DVT)
  • Difficulty passing urine

Specific complications with ACL reconstruction:

  • Break of the kneecap
  • Damage to nerves around the knee
  • Infection in the knee joint
  • Discomfort in the front of the knee
  • Loss of knee movement
  • Recurrent giving way of the knee
  • Severe pain, stiffness and loss of use of the knee (Complex Regional Pain Syndrome)
  • Arthritis
  • Non-surgical alternatives

    In some circumstances, surgery may be avoided completely. This would depend on a number of factors, including how active you are and how severe the injury is. In non-surgical treatments, you will be required to undertake a physiotherapy regime in order to build strength in the muscles surrounding the knee joint in order to help stabilise the knee. However, non-surgical treatments do come with the risk of re-injury and are usually only reserved for minor ligament tears.

    Another alternative treatment is an ACL repair. This is a slightly less invasive surgery which repairs the damaged ligament instead of replacing it.

    Anterior cruciate ligament (ACL) reconstruction consultants at The Holly Hospital

    The Holly Hospital

    High Road, Buckhurst Hill, Essex, IG9 5HX

    020 8505 3311

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