An ACL sprain refers to a tear in the knee joint’s anterior cruciate ligament.
Medically reviewed by Dr Chaminda Goonetilleke, 21st Dec. 2021
Torn ACL symptoms
Torn anterior cruciate ligament (ACL) symptoms include:
- Immediate, intense knee pain.
- A perceived serious incident.
- Audible pop or crack at injury time.
- Possible rapid knee swelling and warmth.
- Potential knee instability when walking.
Rapid swelling arises from joint bleeding due to ruptured blood vessels around and within the ACL.
ACL sprain assessment & diagnosis
A professional therapist will perform tests to diagnose an ACL sprain, including the Anterior Drawer Test and Lachman’s Test.
Imaging
An MRI scan confirms an ACL sprain diagnosis. X-rays are helpful only to detect bone injuries, like avulsion fractures, where a ligament tear pulls a small bone piece away.
What is an ACL Sprain?
An ACL sprain refers to a partial or full tear in the knee’s anterior cruciate ligament, the severity depending on the force of the injury.
Anatomy
The anterior cruciate ligament, running diagonally across the knee, originates from the femur’s back and attaches to the tibia’s front. Its purpose is to restrain the tibia from excessive forward motion.
Causes of ACL Injuries:
- The primary cause is a twisting force in the knee, like when landing from a jump with the foot anchored and the knee twisting inward.
- Contact sports like rugby or football can lead to ACL injuries. Here, a direct hit to the knee’s outer part results in inward buckling and excessive tibia movement, causing damage to the knee structures and an ACL tear.
- Skiing is another common cause, where ski tips digging into the snow lead to a knee twist, causing ACL sprains.
ACL Sprain Treatment:
- Immediate First Aid: If you suspect an ACL injury, seek professional advice promptly.
- Cold Therapy & Compression: For the first 72 hours, or until professional assessment, apply a cold compression wrap for 15 minutes every hour. Avoid direct skin contact to prevent burns.
- Knee Bracing: Use a knee brace, especially for unstable knees. Consider a hinged knee brace for added support. Note that braces or taping cannot entirely prevent injuries.
- Knee Taping: To support the knee post-injury and boost confidence in movement. It’s crucial for unstable knees to protect other structures. Avoid taping without proper knowledge of the injury or taping purpose.
- Professional Advice: If an ACL tear is suspected, seek a professional for a full diagnosis, likely requiring an MRI scan or X-ray. An orthopaedic surgeon may be suggested based on the findings.
- Surgery: Not always necessary for a torn ACL. The decision is often based on the patient’s level of sport and competition participation.
