Anterior Cruciate Ligament (ACL) injury / reconstruction

Introduction

The anterior cruciate ligament (ACL) is one of the most commonly injured ligaments in the knee. It helps provide stability to the knee, especially when you are twisting and turning. It is in the middle of the knee (Figure 1).

An ACL injury can result in the ligament being completely torn or ruptured.

You may report your knee gives way or buckles. This is often when you are twisting and turning.

This leaflet aims to answer the most common questions people ask who have this injury.

How do you injure your ACL?

The ACL can be injured during sporting activities e.g. football, rugby, skiing and basketball. Most people injure their ACL while twisting their knee. You may have felt or heard a ‘pop’ or ‘snap’ at the time of the injury. There is usually immediate knee swelling. You may have struggled to play or work on.

How is an ACL rupture diagnosed?

The diagnosis can be made by taking a detailed history and physical assessment. An MRI scan can be useful in some cases. It can help to establish if the ACL is partially torn or fully ruptured.

How is a ruptured ACL treated?

Unfortunately the ACL does not usually heal by itself. The treatment choices are therefore to live without the ACL (i.e. to have an ACL deficient knee) or to have the ACL reconstructed with an operation.

Making a decision about the management of an ACL deficient knee

Making a decision about how best to manage your knee is based on your function and your personal goals. People who participate in sports or have jobs that require lots of twisting, pivoting and changes of direction may require surgery. This surgery can help them to return to these activities. However many people are able to return to these activities without surgery. They can do so through progressive and regular rehabilitation.

Sometimes, you can injure another structure in your knee at the same time. This could be another ligament or cartilage. This may also influence whether or not surgery is the best option for you.

Rehabilitation after ACL reconstruction (ACLR) requires a long term commitment. Depending on your goals and lifestyle, it may not be necessary to have surgery. You can consider conservative treatment as more appropriate.

If you decide that conservative treatment is most suitable but you are unable to achieve your goals, you can still be considered for ACLR.

ACL Surgical Reconstruction

What does the surgery involve?

In order to replace the torn ligament, most surgeons use the patient’s own tendon. This is known as a graft (substitute) for the new ACL. T his is usually the hamstring tendon on the same leg as the ACL rupture. The tendon used to repair the ACL heals in time.

How long will I be in hospital?

Typically this procedure is done as a day bed case. You should be in and out on the same day. However, you may need to stay in overnight.

What should I expect after the operation?

You may have swelling and pain in your knee after the operation. There may also be some bruising in your thigh and calf.

You will be on crutches for up to 3 weeks. This will depend on your pain, swelling and muscle power. You will be given exercises and advice on walking with crutches by a physiotherapist. This will be done on the ward before you are discharged home.

You will be referred for out-patient physiotherapy.

Your Consultant will arrange to review you several weeks after the operation.

Rehabilitation

A physiotherapist will guide you through a course of physiotherapy. This may last up to 12 months after the operation. During this time you should regain the movement and muscle strength of your knee. This will help in returning to your usual activities/sports.

Most patients attend physiotherapy weekly for the first 4 months after the operation. Some patients are unable to commit to this. In this event, you must try to do the rehabilitation yourself with the advice and guidance of a physiotherapist. The guidance is to help you to achieve your goals. It will also ensure you are not doing too much or too little.

Return to driving

It is advised that you do not drive within the first 6 weeks after the operation. Always inform your insurance company of the operation in case your policy is affected.

Return to work

If you have a desk type job, you can usually return within 4 to 6 weeks. You can work from home before this. If you have a manual job it is recommended that you are off for up to 3 months. The graft is weak in the first few months after the operation. There is therefore a risk that it may be injured again, if abnormally loaded.

Return to sport

After ACLR it is advised that you do not return to sport until 9 to 12 months after the operation. Your physiotherapist will advise you on this further as you progress.

What happens if the operation does not work?

It is rare that the operation does not help. On rare occasions, the new ligament can be injured again. In this event you may need a further operation. Unfortunately the recovery after this procedure takes much longer than the first time.

Risks of surgery

As with all procedures, ACLR surgery carries some risks and complications.

Common (2 to 5%)

• Pain: the knee will be painful after the procedure. Pain relief (analgesics) will be given to prevent this.
• Numbness: the skin around the knee or shin may be temporarily or permanently numb due to damage of the small nerves.
• Swelling/ Haemarthrosis: This is a collection of fluid or less commonly, blood in the knee joint. In most cases, the body will absorb the fluid itself. If the swelling becomes too large, the surgeon may feel an operation is necessary.
• Stiffness: you may have difficulty in straightening your knee or squatting.
• Persistent pain: pain may persist after the procedure. Another knee operation may be required.
• Continued instability: weakness and instability may occur despite adequate surgery.

Less Common (1 to 2%)

• Infection: the wound sites may become red, painful and hot. There may also be a discharge. These are signs of infection and can usually be treated by antibiotics. The infection may spread to the knee joint itself. This may require a washout and removal of the graft. Infection may also spread to the blood (sepsis) requiring intravenous antibiotics.
• Graft rupture: (torn graft) this may occur after further trauma. Further surgery may be necessary.
• Deep Vein Thrombosis (DVT) / Pulmonary Embolism (PE): These are blood clots in the calf/ leg and if they travel to the lungs may be fatal.

Rare (less than1%)

• Damage to structures within the knee: this is rare, but may cause further damage and symptoms. This may need further treatment including operation. These can include fractured knee cap if a patellar tendon graft is used.
• Damage to the skin under the tourniquet: this may require dressing, surgery or skin graft. There may also be temporary numbness of the skin under the tourniquet.
• Damaged instruments: these may break within the knee and require an opening of the joint to remove them.
• Abnormal wound healing: the scar may become thick, red and painful. This is more common in Afro-Caribbeans. There may also be delayed wound healing for numerous reasons.
• Compartment syndrome: a build up pressure within the lower leg and can cause nerve, blood vessel or muscle damage. If this occurs, an emergency operation will have to be performed to prevent death of tissue of the lower leg/ foot.
• Osteoarthritis: development of this can be more common after ACLR.

Conservative rehabilitation of ACL

If you choose not to have surgery, you will be referred to physiotherapy. The aim will be to regain the range of motion and strength around your knee and help to improve your balance. With conservative management, many patients can regain function and return to their daily activities.

Many people will be able to manage with an ACL deficient knee. There is increasing evidence that ACLR should only be considered in people that still have problems after 6 months of rehabilitation. Surgery is usually indicated where there is a history of recurrent ‘giving way’ of the knee. This can occur during twisting activities or activities that involve changes in direction.

It is important to ensure that you do not overload the knee after an acute injury. This will help to prevent any damage and enable you to return to your activities. Following a treatment plan and regular reviews are key to a successful recovery. Your physiotherapist will track your progress and change your treatment plan as needed.

If symptoms persist or worsen, surgical options may need to be reconsidered.

General rehabilitation principles

• Strengthening Exercises - Target muscles around the knee, especially the quadriceps and hamstrings, to improve stability.
• Range of Motion Exercises - To maintain flexibility and prevent stiffness.
• Balance Training - To enhance your knee's ability to stabilize during movement.
• Activity Modification - Your therapist will guide you in modifying activities to prevent further injury.
• Once your symptoms improve and your knee feels stable, you can gradually return to normal activities. Your physiotherapist will create a plan for your safe return to sport or work.

Note: This document is for general informational purposes only and does not replace specific professional healthcare advice. Always consult your healthcare practitioner for a diagnosis and management plan tailored to your individual needs.