ACL Reconstruction (Anterior Cruciate Ligament)

The anterior cruciate ligament (ACL) runs inside the knee from the thigh bone to the shin bone and gives the joint its stability. When it is damaged or lost, the knee becomes prone to ‘giving way’. Once the ligament has torn it cannot usually be repaired, so a new ligament is made from a graft taken from elsewhere in the leg.

Mr Chatenya Chauhan has a particular interest in minimally invasive ACL reconstruction, including refined approaches to hamstring tendon harvesting designed to reduce tissue trauma and support faster rehabilitation. The page below explains the operation, the alternatives and the risks, so that you arrive at your consultation already knowing the questions you want to ask.

The ACL reconstruction procedure

You will be seen by the surgeon on the day of the operation, who will mark your leg with a felt pen to make certain the correct leg is operated on. This is a good moment to ask any remaining questions. An anaesthetic is then given in theatre. This may be a general anaesthetic, where you are asleep, or a local block, where you are awake but the area being operated on is completely numbed. You must discuss the choice and its risks with the anaesthetist.

A tight inflatable band (a tourniquet) may be wrapped around the thigh to limit bleeding. During the operation the surgeon first performs a telescope examination of the knee, an arthroscopy. Small cuts, usually no bigger than 1cm, are made either side of the kneecap through skin that has been cleaned with antiseptic. An arthroscope — a small telescope with a camera at the end, less than the width of a pencil — looks inside the knee and shows the picture on a screen. Other instruments pass through the second cut, so any tidying up of other structures, such as smoothing cartilage, can be done at the same time.

A graft is then taken. Several methods and graft types are available, and the choice depends on the surgeon’s preference and on what suits your case. The two common techniques use either a tendon from the hamstring muscles or part of the ligament running from the kneecap to the shin bone, known as a patellar tendon graft. Both involve making cuts in the skin at the front of the knee.

Tunnels are drilled to allow the graft to pass through the knee joint. The graft is held in position at both ends with screws, pins or slings, and getting the right tension on the new ligament as it is fixed is an important part of the operation. The skin is then closed with stitches or metallic clips.

Waking up and going home

You will wake in the recovery room with a bandage around the knee and will feel sore. That is normal, but if the pain becomes intolerable it is important to tell the nursing staff.

Once you are well enough and have been shown how to walk with crutches you will be allowed home. You should partial weight bear until your surgeon tells you to walk normally. You will almost certainly be started on a rehabilitation and physiotherapy programme, and it is very important that you follow it strictly — rehabilitation does as much for the final result as the operation itself.

Alternatives to surgery

• Some patients simply avoid the activities that make the knee feel unstable.
• Physiotherapy to build up hamstring and quadriceps strength may compensate for the injury, although the knee may still be prone to giving way.
• A brace can take the place of the ligament, and for some patients that is all that is wanted.

If your main problem is arthritic pain rather than instability, a knee injection may be more appropriate than reconstruction. Mr Chauhan will talk you through both routes at your consultation.

Risks of ACL reconstruction

Common (2–5%)

• Pain: the knee will be painful afterwards. Painkillers are given to control this, including enough to take home.
• Numbness: the skin around the knee or shin may be temporarily or more permanently numb because of damage to small nerves.
• Swelling or haemarthrosis: a collection of fluid, or less commonly blood, in the knee joint. In most cases the body absorbs it. If the swelling becomes too large an operation may be needed.
• Stiffness: you may have difficulty straightening the knee or squatting.
• Persistent pain: pain may continue after the procedure, and a repeat arthroscopy or other knee operation may be required.
• Continued instability: weakness and instability can occur despite adequate surgery.

Less common (1–2%)

• Infection: the wound sites may become red, painful and hot, sometimes with a discharge. This is usually treated with antibiotics. Infection can spread to the knee joint itself, requiring a washout and removal of the graft, or to the blood as sepsis, requiring intravenous antibiotics.
• Graft rupture: a torn graft may follow further trauma, and further surgery may be necessary.

Rare (under 1%)

• Damage to structures within the knee: rare, but may cause further damage and symptoms needing treatment or another operation. This includes a fractured kneecap if a patellar tendon graft is used.
• Damage to the skin under the tourniquet: may require dressing, surgery or a skin graft. Numbness of the skin under the tourniquet is usually temporary.
• Damaged instruments: these may break within the knee and require the joint to be opened to remove them.
• Abnormal wound healing: the scar may become thick, red and painful (a keloid scar), which is more common in Afro-Caribbean patients. Wound healing may also be delayed for a number of reasons.
• Compartment syndrome: a build-up of pressure within the lower leg that can damage nerves, blood vessels and muscle. If it occurs, an emergency operation is needed to prevent tissue death in the lower leg and foot.
• Osteoarthritis: this can be more common after joint operations.
• Deep vein thrombosis and pulmonary embolus: a blood clot arising in the veins of the leg, causing pain, redness and swelling. If the clot travels to the lungs it forms a pulmonary embolus, which can severely affect breathing and can be fatal. Tell your doctor if you have a history of clotting or thrombosis, or think you may be at risk.