Anterior cruciate ligament (ACL) injury

What is it?

An ACL injury occurs in the knee through the tearing or over-stretching of the ACL. The tearing could be a partial or complete tear of the ligament. The ACL injury mostly affects women more than men. It occurs commonly during sports such as basketball, soccer, gymnastics, tennis, volleyball and downward skiing. Often when this injury occurs, a “pop” sound can be heard, the knee becomes swollen and extremely painful. It then becomes difficult to put weight on the injured leg and walking becomes a challenge.

Fig 1: Image of a normal and injured ACL

What causes anterior cruciate ligament injury?

This injury occurs when one changes direction suddenly, during pivoting/twisting movements, landing from a jump or when a knee is involved in a sudden stop. An ACL injury can also result from a very hard hit on the side of your knee. Your knee gives out from under you once you tear that ligament.

Fig 2: An image of how an ACL occurs

The link below is a video showing an example of how ACL injuries occur.

Symptoms of the anterior cruciate ligament injury

An ACL injury causes significant knee pain when weight is applied to the knee. Swelling around the knee may also be a symptom of ACL injury, especially in the first few hours following the injury. At the time of injury, many athletes complain of feeling or hearing a loud “pop” from the knee. This is the sound the ligament makes when it ruptures. If you try to put weight on the injured knee, it may give out and feel very unstable. A person suffering from an anterior cruciate ligament injury is also unable to stretch their knee out completely, mostly due to the degree of swelling associated with the injury.

Fig 3: An image of suffering a knee pain

How is the anterior cruciate ligament injury diagnosed?

During a knee examination, your physiotherapist will look for any signs or symptoms of an ACL injury. They will ask you specific questions about how the injury happened and whether you heard any sounds at the time. They will assess for swelling and tenderness around the knee and compare the injured to the uninjured knee. They will perform special tests to determine whether that ligament has been injured. Some of these include the anterior draw test of the knee, Lachman test and pivot shift. Your physiotherapist will also assess your movement to see if it is restricted.

At times, the physical examination is not enough to conclude if you are suffering from the ACL injury. Other methods of diagnosis include:

Ultrasound: This is when sound waves are used to visualise the internal structures of a knee such as the tendons, muscles and ligaments of the knee.

X rays: An x-ray can be used to see if there is any evidence of a fractured bone, however, it cannot scan for soft tissue injuries such as a ligament tear. However, at times an x-ray may be recommended especially if there is a possibility that a person may have had a bony injury, as well as a ligament injury.

Magnetic resonance imaging (MRI): This can be used to visualise both the soft and the hard tissues of the body such as the knee and clearly shows the extent of the injury.

Fig 4: An MRI of a normal and torn ACL

Treatment of an anterior cruciate ligament injury

Immediate first aid to the injured knee can reduce the swelling and the pain. There are four steps you can use to help treat the injury which is summarised using the acronym RICE (Rest, Ice, Compression and Elevation):

Rest is helpful to reduce weight on the affected area.

Elevate the knees on a pillow while lying down.

Ice is used on the injured knee for 20 min after every 2 hours, especially in the first few days.

Compression wraps or an elastic bandage is used to compress the knee.

Compression wraps and ice packs are sold at Masnad Health Clinic. Please visit the website to place your order today! Our therapists also specialise in cryotherapy, which is a type of cold therapy that has been shown to be effective in reducing pain and swelling in ligament injuries.

Rehabilitation

In the acute stage, your therapist may provide you with a knee brace and crutches to facilitate easier mobility. Physical rehabilitation will focus on reducing knee pain, swelling, restore full range of movement, strength, coordination and balance. A therapist can direct you onto exercises to perform at home or under supervision. Your doctor may recommend surgery to reconstruct the injured ligament depending on your age, the extent of the injury and your return to sport goals.

Prevention

These are some of the things you can do to prevent a similar injury. They include:

Wearing proper footwear and padding during sporting activities.

Neuromuscular facilitation exercises such as A skips.

Engaging in exercises that strengthen your leg muscles, specifically the hamstrings.

Training techniques to improve knee coordination, proprioception and balance while jumping.

How long till I get better?

Depending on whether you have had surgery or have managed the injury conservatively (without surgery), the recovery process will be different. The latest research evidence suggests that delaying your return to sport until 9-12 months gives you the best outcome and reduces your risk of re-injury. This decision will be made in collaboration with your Doctor/surgeon, and your physiotherapist.

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Thank you for reading, and we hope you benefited from this article. To receive treatment for your knee injury from our Physiotherapists or Chiropractors,

Call Masnad Health Clinic on (02) 9793 8840

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Anterior cruciate ligament (ACL) injury