Physiopedia:Symptoms and treatment of an Anterior Cruciate Ligament (ACL) injury

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Things to look out for

Please seek immediate help from a suitable healthcare professional if an injury to your knee causes symptoms similar to that of an Anterior Cruciate Ligament (ACL) injury. Signs and symptoms are listed in the article below.

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Overview

The knee joint is made up of three bones; thigh (femur), shin (tibia), and the kneecap (patella). The kneecap gives the joint some protection at the front of the joint. There are ligaments within the knee joint that connect these bones together and provide the joint with stability. The four major ligaments are the medial collateral ligament, lateral collateral ligament, the anterior cruciate ligament (ACL), and the posterior cruciate ligament. There is also the medial and lateral meniscus which provides additional stability and act as a shock absorber in the knee joint.

The Anterior Cruciate Ligament (ACL) is a strong, flexible band of tissue inside the knee joint connecting the femur (thigh) to the tibia (shin). It forms a cross shape with the posterior cruciate ligament. The ACL is an important structure within the knee joint.

The ACL provides stability to the knee. It is vital in preventing the femur sliding backwards on the tibia and stops the tibia sliding forward under the femur. It also resists rotational loads, which occur when the foot is planted and the leg pivots. When the ACL is injured, the knee becomes unstable or may even give way, especially when trying to stop or turn quickly.

Causes

The cause of the injury can be broken down into two.

Non-contact: occurs when the knee is exposed to sudden decelerating forces combined with rotational forces, e.g., changing direction when pivoting, running or landing from a jump. Hyperextension (too much straightening of the knee) or extreme hyperflexion (too much bending of the knee) can also damage the ACL  

Contact: can occur when there is direct trauma or impact to the outside of the knee or lower leg.

Symptoms

When the ACL is injured:

• You may hear a “pop” or feel a popping sensation in your knee.
• You might feel extreme pain and be unable to continue a task or activity.
• There might also be quick onset of swelling .
• Loss of range of motion - you might struggle to bend your knee and straighten your leg.
• Discomfort when walking.
• A feeling of instability or buckling and “giving way” when weight-bearing.

Diagnosis

After a thorough assessment of your knee, your physiotherapist or a doctor may be able to diagnose the injury. To determine the severity of the injury, you may also be referred for an MRI (magnetic resonance imaging) or ultrasound to confirm this. You may also need an x-ray to rule out any bone fractures.

Exercises

evidence-based exercises for the specific condition in terminology/language suitable to patients. be mindful that some patients may not have access to a gym or certain equipment

Management

short and long-term management of condition. medication. general health and wellbeing e.g. nutrition and sleep.

Prevention

evidence-based advice on preventative measures

Resources

links or information on specialist services, charities, or organisations that may offer additional help and support