MRI scan of knee showing complete rupture of the ACL at its top end (Red Arrow). White represents inflammation and the dark grey bottom end of the ligament is intact. MRI is useful for showing other injuries.

Left Knee ACL reconstruction with multiple strand hamstring graft. The new ligament (Red Arrow) is seen in place of the removed damaged ligament with the knee flexed to 90 degrees.

ACL Recostruction

What is the ACL?

The anterior cruciate ligament is one of 4 major ligaments around the knee. It serves to provide central stability to the joint particularly on twisting and pivoting movements.

How is the ACL injured?

It is often injured during sporting activity but occasionally can be torn with minimal trauma. Usually there is a history of twisting of the knee or change of direction with the knee collapsing. There can be an associated “pop” as the ligament fails.

The injury may be accompanied by tears to the meniscal cartilage, joint surface damage or may be part of a multiple ligament injury.

Swelling usually occurs within hours and there is often the feeling of the knee popping out of joint. It is rare to be able to continue playing sport with the initial injury. Once the initial injury settles down the main symptom is instability or giving away of the knee. This usually occurs with running activities but can occur on simple walking or other activities of daily living.

How do I diagnose the problem?

The diagnosis is made from the history of the injury and the clinical examination of the knee. This is often aided by investigations such as an X-ray (to rule out fracture) and an MRI scan which gives detailed information about knee structures.

How do I deal with the injury?

Treatment is always directed to suit the patient. Initial management is to treat the acute knee injury (rest, ice, compression and support) and start early muscle rehabilitation. You may see muscle loss only hours after a knee injury.

With simple rehabilitation and physiotherapy the knee may settle down and be perfectly stable when returning to normal activities.

Do I need surgery?

If the knee is unstable due to the injury then there is the possibility of further damage to other parts of the knee. With simple rehabilitation the knee may improve, but if instability persists then a reconstruction may be required.

Active adult patients involved in sports or jobs that require pivoting, turning or hard-cutting as well as heavy manual work, will tend to require surgical treatment.

Activity and stability, not age, should determine if surgical intervention should be considered.

MRI scan of knee showing complete rupture of the ACL at its top end (Red Arrow). White represents inflammation and the dark grey bottom end of the ligament is intact. MRI is useful for showing other injuries.

Left Knee ACL reconstruction with multiple strand hamstring graft. The new ligament (Red Arrow) is seen in place of the removed damaged ligament with the knee flexed to 90 degrees.


Surgery to reconstruct the ACL involves the use of a graft tissue from around the knee (hamstring tendon or patellar tendon) to rebuild the ligament in the centre of the knee.

The surgery is very successful in 95% of cases but does require a considerable period of recovery and rehabilitation for a full return to sport. This can be up to 12 months in some cases.


If you have an ACL injury you will have rapid assessment in the clinic. You may require confirmatory X-rays and MRI scan to confirm the diagnosis and assess for damage to other structures.

Your immediate early rehabilitation will start with simple measures to reduce swelling and pain whilst promoting return of muscle function. You will be taken through all the available treatment options and your recovery will be tailored to your individual case and needs.

The operation takes approximately 1½ hours and is carried out under general anaesthetic.

After surgery you will stay in hospital for 24 to 48 hours

During this time you will be seen by a physiotherapist who will guide your early recovery and rehabilitation. In the early phase you will concentrate on getting the knee straight – extension exercises. This will improve quadriceps (front of thigh) muscle function and promote a good recovery.

You will be walking after surgery but may require crutches for the first few days until the quadriceps muscles are working well.

You will initially have a bandage on the knee that will be taken down fairly early to allow you to ice the knee (to help reduce swelling). You may be asked to wear a brace at night for a few days to keep the knee straight.

Mr Jennings will review you in hospital after surgery and then in the outpatient clinic at 2 weeks after your surgery to check your progress.

The critical part of the surgery is the rehabilitation which will be guided by a selected specialist physiotherapist. Trying to progress too quickly may damage your knee.

You will need to take a minimum of 2 weeks off for a sedentary or office-based job. More physical or standing work may require a period of up to 6 weeks or more. You may be able to work from home earlier than this, but it is important to concentrate on recovery from surgery as the priority.

For up to 6 weeks there is an extra risk of blood clots in the legs (DVT or deep vein thrombosis) after major knee surgery up to six weeks following operation. During this time long haul flights should be avoided. Shorter flights may be contemplated with much less risk. You should always consider using appropriate precautions including good hydration, regular movement /exercise, use of compression stockings when flying.

It is safer to return to driving later in your recovery to avoid putting your reconstruction at risk. Mr Jennings recommends 6 weeks but will discuss each individual case in detail.

Always check with your car insurance company before getting back on the road. It is important that in an emergency you are able to stop the car safely.


You will return to sport when there is no longer any pain or swelling, when full knee range of motion has been achieved and when muscle strength, endurance and functional use of the leg have been fully restored. Your return will be guided by Mr Jennings and your physiotherapist and may involve some sport specific rehabilitation and training.

Please ask questions if you are unsure or need more clarification as it is important that you have enough information to fully weigh up the benefits and risks of surgery.

General risks of surgery include:

  • Allergies to anaesthetic agents, antiseptic solutions, suture materials or dressings
  • Pain and discomfort around the incisions
  • Nausea, typically from the anaesthetic, this usually settles down quickly
  • Bleeding from the incisions
  • Separation of wound edges
  • Slow healing – most likely to occur in smokers and people with diabetes
  • Wound infections
  • Blood Clots (Deep Vein Thrombosis or DVT, Pulmonary Embolism or PE)

What are the risks of ACL Reconstruction surgery?

  • Infection. This can be reduced by using antibiotics at the time of surgery and by using ‘clean air’ ventilation in theatre. However, infection still occurs in less than 1 in 100 cases. Deep bony infection is very rare but if this occurs and is untreated, serious problems follow. the major symptoms are fever, increasing pain and swelling.
  • · Blood clots. Deep vein thrombosis (DVT) is a possible complication after ACL reconstruction surgery. It is caused by the blood clotting in the veins of the leg in the deep muscles and is associated with pain and swelling of the leg.

Post-operative calf pain, tenderness and swelling are regarded as a serious risk and require immediate investigation and treatment. Normally, this can be done with simple ultrasound scanning and medication. If it occurs at home postoperatively, it needs emergency hospital treatment. It is not a situation to leave to the next clinic appointment.

Rarely a blood clot can move from the leg into the lung, leading to pulmonary embolus. In extreme cases this can be a cause of sudden death, but more often gives rise to chest pain and shortness of breath.

The most important way to avoid blood clots is to get mobile quickly after the operation.

  • Nerve and Blood Vessel Injury. Major nerves and arteries which supply the leg are in the vicinity of the surgery. Although rare, damage to these is possible. Most commonly a nerve to the skin at the front of the leg can be damaged leading to a small patch of numbness on the shin.
  • Stiffness. It is important to work on getting the range of movement back as soon as possible. It is most important to push the leg so that it goes straight as soon as possible
  • Graft Failure. Failure of the graft may occur if excessive forces are placed upon it in the early post-operative period. Your co-operation with all instructions given by Mr Jennings and your physiotherapist will help minimise these complications.

Talk To An Expert Now

Talk To An Expert Now

If you’re somebody who’s struggling at the moment with pain or being active, please do book in to see me.