Anterior Cruciate Ligament (ACL) Injury

Injuries to the anterior cruciate ligament are more common among women and those who play sports such as football, basketball, netball, tennis, and gymnastics, among others. This is because these sports involve start-stop movements, pivoting or sudden changes in direction which causes the knee to twist or turn. The sudden change in momentum or direction makes it more likely for the ACL to stretch or tear.

Other risk factors for ACL tear include:

• Poor conditioning
• Ill-fitting shoes
• Use of sports equipment that is poorly maintained or ill-fitting

Preventing or reducing the risk of an ACL tear

You can reduce your risk of an ACL tear by strengthening your leg muscles and practicing good form.

Strong leg muscles help to protect the knees. Exercises such as squats and lunges help with overall strengthening, and exercises that target the hamstrings may be especially helpful.

Improved core strength and balance improves stability when practicing good form. This includes landing evenly on both feet, bending your knees when landing, aligning your body and feet while landing, and keeping the knees shoulder width apart while landing.

The typical symptoms of an anterior cruciate ligament injury or tear include:

• A popping sound when the ligament ruptures
• Pain immediately after an injury
• Pain when standing or placing pressure on the injured leg
• Difficulty with knee movements or reduced range of knee motion
• Feeling of instability, or loose knee joint, with the knee ‘giving way’ during daily activities
• Swelling of the affected knee within 24 hours
• Difficulty walking or limping while walking

Your doctor will examine your knees and ask you to move your knee in different directions to observe your knee function. Tests such as an X-ray, MRI or ultrasound may also be recommended.

In some cases, a procedure known as arthroscopy may be performed. In an arthroscopy, the orthopaedic surgeon makes small incisions and inserts a small camera so that the type and extent of your injury can be viewed and treated.

Left untreated, an ACL tear can have a significant impact on a person’s level of activity and performance in sports. On-going symptoms such as instability, pain and swelling could make it necessary to modify or restrict your activities, especially sports.

Treatment for ACL tears include non-surgical and surgical options, depending on the extent of injury.

Non-surgical treatment for ACL tears include rest and immobilisation to reduce knee pain and swelling. This is followed by physiotherapy to help:

• restore knee function and range of movement
• strengthen the surrounding leg muscles
• increase stability of the knee

For severe ACL tears, reconstruction surgery may be needed. In ACL reconstruction surgery, the torn ligament is removed by an orthopaedic surgeon and replaced with a piece of tendon taken from another part of your knee or from a donor. Surgery may be recommended for:

• athletes who wish to continue in their sport
• those whose injury involves more than one ligament or damage to the meniscus
• those who are experiencing knee buckling during normal daily activities

What can you expect in an ACL reconstruction?

ACL reconstruction is performed under general anaesthesia which means you will be asleep. The procedure is known as arthroscopy. The orthopaedic surgeon will make several small cuts or incisions. These will allow the insertion of a small camera and surgical instruments for the surgeon to remove the damaged ligament and replace it with a piece of tendon, enabling new ligament tissue to grow. The tendon will then be secured to surrounding bones.

You may be allowed to go home on the same day, using crutches and a knee brace or splint. Post-operative pain and swelling is normal, and you will be advised on medications, icing and elevating your leg to relieve the pain and swelling.

Physiotherapy will help to strengthen the muscles around the knee and improve flexibility. Overall recovery takes around nine months though athletes may require a longer recovery time before they can return to their sport.

Consult an orthopaedic surgeon to determine the treatment method most suitable for you.

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A common complication from an ACL tear is a significantly higher risk of developing arthritis. This increased risk remains regardless of whether the tear was surgically repaired, leading experts to believe that the inflammatory response of the knee to the injury itself contributes to the development of arthritis.

It is estimated that 70 – 80% of people who experience a torn ACL will experience the onset of arthritis within 10 – 15 years. As ACL injuries are common among younger people and athletes, this could mean that the onset of arthritis can occur in the prime of their lives.