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ACL reconstruction surgery man holding knee in pain
By In-house Team, Circle Health Group

ACL reconstruction surgery Q&A

Three of our leading orthopaedic specialists answer common questions on ACL reconstruction surgery including what's involved in the procedure and recovery, possible side effects, and alternative options

The Consultants

Mr Richard Boden, a consultant trauma & orthopaedic surgeon at The Beardwood Hospital

Mr Julian Flynn, a consultant orthopaedic surgeon at The Saxon Clinic

Mr Wiqqas Jamil, a consultant orthopaedic knee surgeon at The Highfield Hospital and The Alexandra Hospital

What is the ACL (anterior cruciate ligament)?

Mr Richard Boden:The anterior cruciate ligament is a band of tissue within the knee, approximately 3cm in length. It connects the tibia (shin bone) to the femur (thigh bone) and is the primary stabiliser of the knee, mainly in sporting activities including rotation and side stepping.

Mr Julian Flynn:The anterior cruciate ligament (ACL) is one of the 'crucial' ligaments running through the centre of the knee. There are four main ligaments around the knee, one on either side of the joint - called the collateral ligaments, and two centrally called the posterior and anterior cruciate ligaments. The ACL is the main restraint to the tibia (shin bone) slipping forward on the femur (thigh bone). The ACL also has the important function in controlling rotation of the shin bone on the femur to maintain stability of the knee when performing sports or activities with twisting movements of the knee. It is one of the commonest ligaments to be injured, usually with a severe twist of the knee with the foot fixed, or with a force to the outside of the knee.

Mr Wiqqas Jamil:The ACL is a fibrous band of tissue that is just under 4cm in length and links the thigh bone (femur) with the shin bone (tibia). The ACL functions as stabiliser of the knee and is the primary restraint to limit forward translation of the tibia on the femur. It is also the main proprioceptor in the knee, telling the brain where the knee is in space and time.

The main reason for reconstructing the ACL is to try and restore normal stability, range of motion and strength of the knee.

Mr Julian Flynn, Consultant Orthopaedic Surgeon

What are the reasons for ACL reconstruction surgery? How can you avoid injury to your anterior cruciate ligament?

Mr Richard Boden: The ACL is most commonly injured during sports that involve jumping, turning and side stepping. Skiing and ball sports are commonly associated with ACL injury. Patients frequently hear or feel a snap within the knee and are unable to continue their activity. The injury is usually associated with rapid swelling of the knee, initially eased by rest, ice and compression. As the swelling settles, however, pain or instability may be noted, particularly on turning.

ACL injury is difficult to avoid due to its occurrence during sporting activities, but maintaining fitness and generalised muscle tone around the knee will help, as will warming up prior to activities.

Mr Julian Flynn: The main reason for reconstructing the ACL is to try and restore normal stability, range of motion and strength of the knee. The decision to undergo reconstruction is based on clinical grounds if a patient has a feeling of instability on the knee, or cannot trust the knee when turning or twisting. After reconstruction it is vital to follow a rehabilitation protocol overseen by a Physiotherapy Team to ensure that the new cruciate ligament graft is protected and allowed to heal. At the same time, objectives include regaining a full range of motion in the knee and thus allowing restoration of muscle strength and proprioception – the ability of the body to know where the joint is in space, and the ability of muscles to control the joint.

Mr Wiqqas Jamil: ACL reconstruction is performed to stabilise the knee and in doing so allowing return to sports that involve pivoting movements. The procedure helps to protect other structures in the knee as well as the joint surfaces.

ACL injury is caused by contact and non-contact mechanisms. There are a number of risk factors (including hormonal, anatomical and biomechanical) that are associated with increased risk of ACL injury. Preventing injury altogether is not always possible but the risks can be reduced through biomechanical musculoskeletal conditioning and injury-prevention programs.

What does the procedure involve?illustration of a knee with a torn ACL

Mr Richard Boden: You will be admitted on the day of surgery and discharged either that evening or the following morning. The surgery is performed arthroscopically (keyhole surgery) using a hamstring autograft (your own tendons from the same knee). This technique involves a general anaesthetic and a local anaesthetic block (extra painkilling anaesthetic placed in the area of the knee to aid rapid recovery).

A full examination and diagnostic arthroscopy are performed and the hamstring graft is harvested. Usually two of the hamstrings are taken, preserving the remaining hamstring tendons and muscles to maintain knee function. Tunnels are drilled into the tibia and femur and the tendon grafts are passed across the knee, securely fixing them to reconstruct the torn ACL. You will have the wounds dressed and a bandage placed, which will be removed after 24 hours. Physiotherapy will start immediately. You will be on crutches for approximately 7 days (or less if possible) with no brace or immobilisation of the knee.

Mr Julian Flynn: The operation involves taking either a graft from the patient (usually either their hamstring tendons, or part of the patella tendon) or using a cadaveric graft in some instances. Bony tunnels are drilled through the tibia and femur, and the graft is then taken across the joint and fixed in the bony tunnels to try and reproduce the anatomy of the old ACL. This should restore much of the stability of the knee, but it is important to note that it is not possible to produce a normal knee in all cases. Additional procedures such as meniscal repair may be required at the same time, as meniscal injuries or injuries to the surface cartilage frequently occur at the same time as the ACL injury.

Mr Wiqqas Jamil: An MRI scan is often performed to assess the ACL and surrounding structures. Occasionally arthroscopic evaluation prior to reconstruction may be required, which is where you have a separate keyhole operation to assess the damage to your knee. Physiotherapy may also be required before ACL reconstruction. ACL reconstruction surgery can be performed through a number of techniques including open and arthroscopic (keyhole), and there are a variety of tissues that can be used as a graft to substitute for the torn ACL.

Conservative treatment mainly involves physiotherapy to strengthen the knee and improve proprioception (the body's awareness of the position of the knee).

Mr Richard Boden, Consultant Trauma and Orthopaedic Surgeon

What are the alternatives to ACL reconstruction surgery?

Mr Richard Boden: Conservative treatment mainly involves physiotherapy to strengthen the knee and improve proprioception (the body's awareness of the position of the knee). This treatment will usually encourage a stable knee when performing linear movements (those in a straight line), but instability can still be felt on turning and side stepping. A proportion of patients can get back to competitive sports with this treatment, but most find the knee to be unstable and at risk of further injury. Most sporting patients elect for an ACL reconstruction.

Mr Julian Flynn: Not all patients with a rupture or partial rupture of the ACL actually require a full reconstruction. Those individuals with a sedentary lifestyle, or whose sporting aspirations do not include twisting and pivoting, may be able to cope with a rehabilitation protocol that strengthens their quadriceps and hamstring muscles and may regain enough proprioception using this method that they can avoid surgery. The use of a brace after an ACL injury or after ACL reconstruction is controversial and should be based on an individual's requirements and the degree of laxity in their knee.

Mr Wiqqas Jamil: Alternatives to surgery depend on an individual's functional requirements and recreational needs. Conservative management can be through certain activity avoidance, conditioning of knee musculature, proprioceptive conditioning, and on occasions bracing.

Are there any risks or side effects to the procedure?

Mr Richard Boden: 90% of patients experience a successful outcome after ACL reconstruction, though you can expect some deterioration of the knee over time. The risks of surgery are the same general complications seen in most surgical procedures including blood clots, infection, bleeding or nerve injury. Specific risks of graft failure (2% initially then 1% per year thereafter), hamstring tears and knee stiffness are also present.

Mr Julian Flynn: ACL reconstruction is a significant operation and the main and obvious risks are the possibility of infection, swelling and stiffness. Subsequent risks include the possibility of the graft stretching and, therefore, becoming non-functional, or completely re-rupturing once an individual returns to sport. However, after an ACL reconstruction the main risk on returning to sport is sustaining a similar injury to the other knee. In the ten years after an ACL reconstruction there is around a 25 percent chance of requiring further arthroscopic surgery for damage to other structures including the meniscus.

Mr Wiqqas Jamil: Yes - there are risks involved with any surgery. In ACL reconstruction they include overall general risks of up to 5% but the risk of serious complications is in between 1-2%.

In this video, consultant orthopaedic surgeon Nev Davies from Circle Reading Hospital shares what to expect from an ACL reconstruction done through keyhole surgery.

How long does it take to recover from ACL reconstruction surgery?

Mr Richard Boden: Most patients are off crutches at about a week, walking normally and driving at about 2 weeks. Return to sports can occur gradually, solo sports at about 3 months, non-contact at 6 months and contact sports at 1 year (this will be led by your physio team).

Mr Julian Flynn: ACL reconstruction surgery is now generally performed on a day case basis, although patients may need to stay in overnight for pain relief if required. In general, time frames depend on the specific recovery of each individual but it commonly takes twelve months to return to contact sports. Short-term recovery is guided by physiotherapy rehabilitation with an emphasis on reducing swelling, improving pain and therefore improving range of motion, which will allow muscles to recover. During this time the graft will initially lose strength before healing with new cells and blood vessels to form new living tissue.

Mr Wiqqas Jamil: You will be walking on crutches the same day and discharged either the same or the following day. Wound healing takes 2-3 weeks. Post-operative physiotherapy is started within 7-14 days of the reconstruction and return to contact sports is between 9-12 months.

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