ACL (Anterior Cruciate Ligament) Reconstruction

Anterior cruciate ligament reconstruction surgery replaces the ACL ligament with a new ligament to improve stability and to decrease the chances of having cartilage injuries.

Who is a Candidate?

People who have knees that:

  • Are unstable
  • Tend to give away during activities
  • Make them incapable of playing sports

How does the ACL get injured?

The most common mechanism of injury is from a non-contact injury that typically occurs whilst attempting a pivoting or cutting (change of direction) manoeuvre whilst playing sport. The injury can also occur from contact activity (e.g. being tackled from the side) when your knee buckles inwards whilst the leg is held in a fixed position.

Not uncommonly, a “cracking or popping” sensation is felt at the time of the injury. The injury is associated with a lot of swelling within the knee that typically occurs at the time of, or soon after the injury. The leg is often painful to walk on for several days.

When is an ACL reconstruction helpful?

If your knee is giving away regularly and this is interfering with your quality of life, you may want to consider an operation. This instability may occur during sport or during activities of daily living. Most patients who want to return to pivoting sports will require a reconstruction to prevent their knee buckling during these activities.

Other associated injuries

An ACL rupture may be associated with an injury to other stabilising ligaments within the knee. Rupture of your ACL is commonly associated with tears that involve the shock absorbing cartilages (menisci) of the knee. Depending on the location and size of these tears they may be surgically repaired or excised at the time of your surgery. Bruising of the bone also occurs at the time of injury because your thigh and leg bones are driven into each other by the violent forces that cause the ligament to rupture. No specific treatment is required for this “bone bruising”.

What is Anterior Cruciate Ligament Reconstruction Surgery?

The ACL is a ligament in the center of the knee that prevents the shin bone (tibia) from moving forward on the femur (thigh bone). A tear of this ligament can cause the knee to give away during physical activity. If a torn ACL is left untreated, cartilage damage and early arthritis may occur. ACL reconstruction is surgery to replace the torn ligament. There are several choices of tissue to use for the new ligament, including an autograft (tissue from the patient’s own body) or an allograft (tissue from a donor). The most common autografts use the hamstring tendons.

The procedure is usually performed by having a camera inserted into the knee, which is known as knee arthroscopy. The camera is connected to a video monitor. The surgeon evaluates the cartilage and ligaments of the knee by viewing the monitor.Additional small incisions are made around the knee to put the new ligament in place. The old ligament will be removed using a shaver. Bone tunnels will be made to place the new ligament in the knee at the site of the old ACL. If the patient’s own tissue is to be used for the new ligament, a incision will be made to take the tissue. The new ligament is then fixed to the bone using screws or other devices. At the end of the surgery, the incisions are closed and a bandage is applied.

What happens on the day your operation?

You will be admitted to hospital on the day of your surgery. Your anaesthetist will discuss with you the type of anaesthetic you will have and your options for postoperative pain relief. Most patients have a general anaesthetic. Antibiotics are delivered via a drip to decrease the risk of developing an infection. After your anaesthetic has been administered, a tight band (tourniquet) will be applied to your upper thigh and everything except your knee will be covered by sterile drapes.

one of your hamstring tendons semitendinosus will be removed from the back of your thigh through an incision on the front of your knee. This is done with a special instrument called a tendon stripper. In some cases (eg. a revision operation), the kneecap ligament (the middle third of the patellar ligament) or the hamstring tendons from your opposite leg may need to be used.

With the aid of a specialised telescope (arthroscope), the inside of your knee is inspected for any associated damage. If any is found (eg. a meniscal tear), it will be addressed at the time of surgery.

A tunnel will be drilled in the top of your leg bone (tibia) and the bottom of your thigh bone (femur). The tendons will be passed through these tunnels and anchored in place with specialised devices (screws and buttons) to provide stability to your knee.

Your knee will be injected with local anaesthetic to help with your post operative pain control. All your wounds will be closed using a combination of normal and dissolving sutures. Your leg will then be wrapped in a well-padded dressing prior to leaving the operating theatre. A brace is not usually required after your surgery. You will wake up in the recovery ward where you will be closely monitored until you are ready to return to your ward. Here you will continue to be observed until you are fully awake.

An xray of your knee will be taken the day of your surgery.

During your stay, you will be seen by a physiotherapist who will provide instructions for exercises for you leg that can be performed whilst in bed. The aims of these visits are to regain motion in the knee, gradually improve your mobility, teach you exercises to maintain muscular strength around the knee and control your knee swelling. They also help prevent you from developing a chest infection.

You will be able take all your weight through the operated leg after the operation. Once you are mobilizing safely, have regained appropriate motion in the knee and your pain is controlled by oral pain medication you will be able to go home. The majority of patients are able to be discharged home the same day as their surgery.

How long does rehabilitation take after surgery?

Physical therapy is done in a supervised setting in conjunction with a trained therapist. Early in the course of recovery, visits may be 2 to 3 times per week, but later once every week or two is often sufficient. Home exercises are done on days not scheduled for a formal therapy session.

The rehabilitation following ACL reconstruction includes essentially three phases. The first phase of rehabilitation consists of controlling the pain and swelling in the knee, regaining knee motion, and getting early return of muscle strength. The operated leg is typically placed into a hinged brace after surgery.

Initially, weight-bearing is allowed with crutches and is progressed to full weight bearing independent of crutches as swelling, motion, and muscle strength allow. Most patients are on crutches for one week, although some may be on crutches longer and some shorter. This phase typically takes 6 to 8 weeks.

The second phase emphasizes continued control of swelling and recovery of full muscle strength. Cycling, treadmill running, and light jogging are started in this phase. In some patients, a sport brace is obtained to replace the postoperative knee brace. This phase typically lasts from 2 to 4 months after surgery.

The final phase consists of graduated return to full activity. Full motion, normal muscle strength, and the absence of swelling are required for successful return to activity. A brace may be recommended early in the return to activity.

A patient’s rehabilitation is monitored closely by both the therapist and surgeon for evidence of potential problems. Most significantly, patients are cautioned not to attempt too premature return to full activity which may cause the knee to be inflamed or re-injured. In every patient the graft must both heal into place and be incorporated into the knee: too much stress too soon may increase the risk of graft failure.