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Anterior Cruciate Ligament Reconstruction, ACL Reconstruction

This is an example of an advice leaflet for anterior cruciate ligament reconstruction. It should not be taken literally as your unit may give different advice.

Introduction to ACL reconstruction

We expect you to make a rapid recovery after your operation and to experience no serious problems. However, it is important to know about minor problems which are common after this operation, and also about more serious problems that can occasionally occur. The section “What problems can occur after the operation?” describes these, and we would particularly ask you to read this. The headings from this section will also be included in the consent form you will be asked to sign before your operation.

What is anterior cruciate ligament reconstruction?

In this procedure, the ruptured anterior cruciate ligament, an important stabilizing ligament in your knee, is reconstructed using two hamstring tendons taken from the same knee.

What is the anterior cruciate ligament?

The anterior cruciate ligament may be ruptured during sport or after an accident or a fall. It is one of the major stabilizing ligaments within the knee and damage to the ligament may lead to feelings of the knee giving way.

Anterior cruciate ligament (ACL) reconstruction surgery helps to control this feeling of giving way by preventing too much abnormal movement between the tibia (shin bone) and the femur (thigh bone) and also by helping the knee to recognize when it is about to slip (proprioception or joint position sense).

Alternative treatments

Some people are able to manage well after injury without needing surgery. Physiotherapy, by increasing proprioception and building up your quadriceps and hamstring (thigh and leg) muscles, can help to make the knee feel more stable. Unfortunately, although this stability may be sufficient to cope with careful everyday activities, such a knee rarely stands up to competitive sport.

The knee may remain unstable on sudden changes of direction, with a feeling of insecurity and slipping of the knee. Artificial grafts to replace the ACL have not proved to be successful over the years, so we use the body’s own tissues.

Information about the diagnosis

Your surgeon may be able to make the diagnosis of ACL rupture by examining your knee and discovering excess movement in the knee. You may need an MRI scan to confirm the diagnosis if there is doubt, or alternatively the diagnosis may be made during arthroscopy of the knee, a keyhole day case operation.

What does the procedure involve?

During surgery the graft is taken from two hamstring tendons that pass along the back and inner side of the knee. The graft is taken through a 3-4 centimetre skin incision on the tibia. Then, using an arthroscope and special aiming devices, small bone tunnels are drilled in the tibia and the femur in the location where the injured anterior cruciate ligament used to be. Once the graft has been passed through the bone tunnels, the new graft is fixed securely in place using a metal toggle and a screw, which remain within the knee permanently.

What about the anaesthetic?

The operation is usually carried out under a general anaesthetic. In addition the anaesthetist may use nerve blocks (local anaesthetic injections) to temporarily numb the leg for a few hours after surgery and ease the pain following the operation.

What happens after the operation?

You may have attended a pre-admission clinic before the operation. There you will meet a physiotherapist who will show you specific exercises to do after surgery. You will also meet a nurse who ask you questions about your health and help answer any questions you might have. Your surgeon will see you before surgery to discuss the operation, obtain your consent and answer any questions you may have regarding the operation.

What happens after the operation?

When you return to the ward after surgery your knee will be bandaged and will feel a little numb and heavy if you have had a nerve block. The block will start to wear off overnight. You will also be given painkilling tablets to ease the aching on the first day. The next morning the bandages will be taken off and a cold compress will be applied to the knee (a cryocuff). This helps reduce pain and swelling. A physiotherapist will see you in the morning and get you out of bed, helping you to stand with crutches. The surgical team will organize an x-ray of your knee. You are encouraged to take regular painkillers that day to allow you to do your exercises comfortably.

Discharge from hospital

Once you are safe on crutches, your pain is well controlled and the knee not excessively swollen, you will be able to go home. This may be the day following your surgery or occasionally two days after surgery. You should use your crutches for the first two weeks and follow the instructions that your physiotherapist has given you.

Before you leave hospital you will be given an outpatient appointment to return to the clinic in two weeks for the knee to be checked. You should not return to work until after this review.

When can I drive?

In order to be able to drive safely your knee needs to be comfortable and mobile. You also need to be able to carry out a controlled emergency stop. It usually takes six weeks to be able to reach this point after anterior cruciate ligament reconstruction.

When can I return to work?

You should plan to take up to six weeks off work to get over your surgery. Some patients feel able to return to sedentary work earlier, say at three weeks. Light work is usually possible at 4-6 weeks. Heavy manual work (ladders, scaffolds, etc.) are best avoided for three months.

What problems can occur after the operation?

A variety of problems can occur after an operation.

Wound problems

The small wounds usually heal quickly but you may notice some numbness around the scar. This is temporary but occasionally some tiny skin nerves around the wound can be damaged and this numbness may be long term.


There is a small risk of infection as with any surgery. The risk is about 1%. You will be given antibiotics at the time of your operation to minimize this risk. If you do get an infection in the knee joint you will need to have further surgery on the knee to reduce the risk of developing arthritis as a result of the infection.


During the early weeks you are likely to notice a little swelling of the knee as well as some soreness along the inner side of the thigh in the area where the hamstrings have been removed. You may also notice some bruising around the ankle. This is normal and will settle. If the swelling or bruising is excessive and making the knee very uncomfortable you may have to have the fluid drained, either in the outpatient clinic or under a short anaesthetic in the operating theatre.

Deep vein thrombosis (DVT)

Deep vein thrombosis is possible but uncommon. If you are at particular risk then special precautions will be taken to reduce the risk. Moving your legs and feet after the operation and walking about early all help to stop thrombosis occurring.

Graft failure

Stretching of the new graft always occurs to some degree. There may always be a little more play in the knee when compared with the un-injured side. This is not a great concern as the knee usually continues to function well despite this. In some cases though (about 3%) the graft stretches out far enough for the knee to start giving way again. In order to minimize this risk you should stick with the rehabilitation programme that the physiotherapist gives you and do not be tempted to “try the knee out” until you are given the go-ahead to do so.

Knee stiffness

Your knee movement should return gradually over the next few weeks. The physiotherapist will aim to have the knee bending to a right angle (90 degrees) within two weeks of surgery. Further movement will be introduced gradually so as not to stretch the new ligament. The most common cause of knee stiffness is swelling, which can be controlled by the measures described above. You may notice a slight loss of the extreme of knee bend following this surgery. This may be unavoidable.

The risks of a general anaesthetic

General anaesthetics have some risks, which may be increased if you have chronic medical conditions, but in general they are as follows:

  • Common temporary side-effects (risk of 1 in 10 to 1 in 100) include bruising or pain in the area of injections, blurred vision and sickness. These can usually be treated and pass off quickly.
  • Infrequent complications (risk of 1 in 100 to 1 in 10,000) include temporary breathing difficulties, muscle pains, headaches, damage to teeth, lip or tongue, sore throat and temporary problems speaking.
  • Extremely rare and serious complications (risk of less than 1 in 10,000). These include severe allergic reactions and death, brain damage, kidney and liver failure, lung damage, permanent nerve or blood vessel damage, eye injury and damage to the voice-box. These are very rare and may depend on whether you have other serious medical conditions.

What should you do if you develop problems?

If you develop problems due to increased swelling or pain, rest the knee, use a cold compress on the knee and take some painkillers. If your symptoms persist you should contact your physiotherapist, or they are not reachable you should contact your GP.

Do you need to return to hospital for a check?

If your physio or GP are concerned, or if your symptoms are worsening please contact the surgeon’s secretary or a member of his team, who will arrange for you to have a check up in outpatients.

Who should you contact in an emergency?

In case of emergency you should contact the nearest on-call general practitioner. If they are unavailable then you should attend your nearest Emergency Department.

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