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Anterior Cruciate Ligament (ACL) Reconstruction

ACL Reconstruction Patellar Tendon

ACL Reconstruction Hamstring Method

The anterior cruciate ligament is one of the major stabilizing ligaments in the knee. It is a strong rope like structure located in the centre of the knee running from the femur to the tibia.

When this ligament tears, unfortunately it doesn't heal and often leads to the feeling of instability in the knee.

ACL reconstruction is a commonly performed surgical procedure and with recent advances in arthroscopic surgery can now be performed with minimal incisions and low complication rates.

Function

The ACL is the major stabilizing ligaments in the knee. It prevents the tibia (Shin bone) moving abnormally on the femur (thigh bone). When this abnormal movement occurs it is referred to as instability and the patient is aware this abnormal movement.

Often other structures such as the meniscus, the articular cartilage (lining the joint) or other ligaments can also be damaged at the same time as a cruciate injury & these may need to be addressed at the time of surgery.

Causes

An ACL injury most commonly occurs during sports that involve twisting or overextending your knee. An ACL can be injured in several ways:

  • Sudden directional change
  • Slowing down while running
  • Landing from a jump incorrectly
  • Direct blow to the side of your knee, such as during a football tackle

Symptoms

When you injure your ACL, you might hear a loud "pop" sound and you may feel the knee buckle. Within a few hours after an ACL injury, your knee may swell due to bleeding from vessels within the torn ligament. You may notice that the knee feels unstable or seems to give way, especially when trying to change direction on the knee.

Diagnosis

An ACL injury can often be diagnosed based on the history along. A thorough physical examination of the knee will reveal instability. Diagnostic tests such as X-rays and MRI scans are often ordered. X-rays may be needed to rule out any fractures and an MRI can be used to confirm the ACL tear and to look for damage to other structures in the knee.

In addition, your doctor will often perform the Lachman’s test to see if the ACL is intact. During a Lachman test, knees with a torn ACL may show increased forward movement of the tibia and a soft or mushy endpoint compared to a healthy knee.

Pivot shift test is another test to assess ACL tear. During this test, if the ACL is torn, the tibia will move forward when the knee is completely straight and as the knee bends past 30° the tibia shifts back into correct place in relation to the femur.

Treatment

Initial Management

  • Rest
  • Ice
  • Elevation
  • Bandage

Long Term Management

Not everyone needs surgery. Some people can compensate for the injured ligament with strengthening exercises or a brace.

It is strongly advised to avoid sports involving twisting activities, if you have an ACL injury. Episodes of instability can cause further damage to important structures within the knee that may result in early arthritis

Indications for Surgery

Young patients wishing to maintain an active lifestyle.

Sports involving twisting activities (e.g., Soccer, netball, football). Giving way with activities of daily living.

People with dangerous occupations e.g., Policemen, firemen, roofers, scaffoulders.

It is advisable to have physiotherapy prior to surgery to regain motion and strengthen the muscles as much as possible.

Surgery

Surgical techniques have improved significantly over the last decade, complications are reduced, and recovery much quicker than in the past.

The surgery is performed arthroscopically. The ruptured ligament is removed and then tunnels (holes) in the bone are drilled to accept the new graft. This graft which replaces your old ACL is taken either from the hamstring, patella, or quadriceps tendon, or a cadaver graft may be used. There are advantages & disadvantages of each graft, and your surgeon will discuss these options with you prior to surgery.

The graft is prepared to take the form of a new tendon and passed through the drill holes in the bone.

The new tendon is then fixed into the bone with various devices to hold it into place while the ligament heals into the bone (usually 6 months).

The rest of the knee can be clearly visualized at the same time and any other damage is dealt with (e.g., meniscal tears).

The wounds are then closed and a dressing and knee brace is applied.

Risks and complications

Possible risks and complications associated with ACL reconstruction with hamstring method include:

  • Numbness
  • Infection
  • Blood clots (Deep vein thrombosis)
  • Nerve and blood vessel damage
  • Failure of the graft
  • Loosening of the graft
  • Decreased range of motion
  • Crepitus (crackling or grating feeling of the kneecap)
  • Pain in the knee
  • Repeat injury to the graft

Post-operative care

Following the surgery, rehabilitation begins immediately. A physical therapist will teach you specific exercises to be performed to strengthen your leg and restore knee movement. The early aim is to regain range of motion, reduce swelling and achieve full weight bearing.

The remaining rehabilitation will be supervised by a physiotherapist and will involve activities such as exercise bike riding, swimming, proprioceptive exercises and muscle strengthening. Cycling can begin at 2 months, jogging can generally begin at around 3 months. The graft is strong enough to allow sport at around 6 months however other factors come into play such as confidence, fitness and adequate fitness and training.

Professional sportsmen often return at 6 months but recreational athletes may take 10 -12 months depending on motivation and time put into rehabilitation.

The rehabilitation and overall success of the procedure can be affected by associated injuries to the knee such as damage to meniscus, articular cartilage or other ligaments.

Anterior Cruciate Ligament reconstruction is a common and very successful procedure. In the hands of experienced surgeons who perform a lot of these procedures 95% of people have a successful result. It is generally recommended in the patient wishing to return to an active lifestyle especially those wishing to play sports involving running and twisting.

The above information hopefully has educated you on the choices available to you, the procedure and the risks involved. If you have any further questions you should consult with your surgeon.

Anterior Cruciate Ligament (ACL) Reconstruction - AAOS link