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Anterior Cruciate Ligament Tear (ACL Tear)

What you need to know about a torn anterior cruciate ligament (ACL), its symptoms and treatment.

What Is the Anterior Cruciate Ligament (ACL)?

The anterior cruciate ligament, also called the ACL, is one of the four major ligaments of the knee helping to prevent excessive motion of the knee joint. It is commonly injured during sporting activities , for example during tackling in football, and pivoting or landing from a jump.

The ACL is an important structure that joins the thigh bone (femur) to the shin bone (tibia). It prevents the shin bone from moving forward excessively under the thigh bone.

Related: Aches and Pains

What Are the Common Causes of ACL Injury?

The ACL is commonly injured when there is an excessive strain on the ligament from:

• Direct trauma — direct blow to the side/behind the knee

• Pivoting — twisting of the femur while the tibia is still stationary e.g. sudden change of direction while running

• Hyperextension (overextension) — this usually happens when landing from a jump

Related: Step Into It

ACL Tear Signs and Symptoms

A tear of the ACL is usually accompanied by:

• A "POP" sound

• Intense pain

• Immediate swelling

• Inability to put weight on injured leg

• "Giving way" of the knee

Following an ACL injury, you may experience:

• Pain and swelling

• Loss in range of movement

• Knee instability

Related: Knee Arthritis

What Are the Risk Factors of an ACL Tear?

• Sports — athletes engaging in sports that require a lot of cutting and/or pivoting e.g. basketball, soccer, rugby.

• Gender — women are significantly more at risk than men as they tend to have greater thigh muscle imbalances due to weaker hamstrings compared to their quadriceps. Women also have a greater Q-angle of the patella, also known as knee cap, (which places the knee in a more 'inward' position), and therefore are at a bio-mechanical disadvantage.

• Poor strength and conditioning — you may be "unfit" for certain sports which have a higher demand for body strength and conditioning.

• Environmental — uneven exercise terrain or a wet exercise surface due to poor weather may increase the chance of an ACL injury.

What Types of ACL Treatment are Available?

An ACL injury will result in knee instability and buckling. This is due to knee muscles weakening secondary to pain or muscle disuse. The first-line treatment is to go for conservative management in order to achieve the following goals:

• Reduce knee pain and swelling

• Increase range of knee movement

• Increase muscle strength

• Increase stability of the knee

Physiotherapy

The above goals are achieved using a range of physiotherapy treatments, including electrophysical agents and exercise therapy. Treatment is progressed over a period of three to six months, and improvements are unique to each individual, depending on the severity of the injury. Compliance with the home exercise programme prescribed is necessary to enable an early return to sports.

There is a possibility that following a period of conservative management, the knee may still buckle or give way. This usually occurs in contact sports such as soccer or rugby. Failure to respond successfully to conservative management may indicate the need for ACL reconstruction surgery.

Surgery

ACL reconstruction surgery involves replacing the torn ACL with a graft taken from a tendon around the knee.

Commonly-harvested tendons are the patella tendon and the hamstring tendon. The graft is then attached to run in a similar direction as the ACL.

What Can I Do to Help Myself?

Dos

• Protect your knee by wearing your knee brace especially when you still experience buckling or give way

• Rest from sports and avoid cutting or pivoting

• Ice your knee whenever possible and after doing your exercises

• Apply compression bandage to reduce swelling

• Elevate your leg while resting or sleeping to reduce swelling

• Strengthen your muscles as instructed by your physiotherapist

• Inform your physiotherapist if you have any knee pain or swelling after exercises

Don'ts

• Return to any sporting activity when you still have weakness in muscles

• Change or add new exercises to your home exercise programme without discussing with your physiotherapist

Related: KneeBuddy App

 Frequently Asked Questions

1. What can I expect after my surgery?

There are some milestones that can be achieved as your rehabilitation progresses. They are:

• Commence jogging at three months

• Commence light sports training at six months

• Commence competitive sports at nine months

Don’t be disappointed if you do not reach these milestones at the given time frame. Continue to work at it! Your ability to return to sports depends on your commitment to the exercises given. Your doctor and physiotherapist will also clarify any restrictions on sports participation based on the outcome of your surgery and the progress of your rehabilitation.