Anterior cruciate ligament injury may involve a complete or partial tear within the substance tear of the ligament or an avulsion from the bone.

Page updated July 2023 by Dr Sheila Strover (Clinical Editor)

Sherman Type 1 ACL injury

Sherman Type I ACL injury - the ACL has torn off at the bony attachment site in the roof of the notch.

Sherman type IV tear of ACL

Sherman Type IV ACL injury - right through the mid-substance of the ligament.


Mechanism of injury of the ACL

A common mechanism of injury is sudden pivoting on that leg when the foot is on the ground and the weight on the same leg.

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How is a torn ACL diagnosed?

Firstly there will be a high index of suspicion - the patient may have had a high momentum injury, heard a loud 'pop!' and been unable to walk after the injury. The knee may have immediately swelled up, and even after some days of rest the knee may feel unstable.

The clinician may test for laxity, classically using the 'anterior drawer' test. Laxity may also be tested objectively with an instrument such as the KT-2000

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Can a torn ACL heal on its own?

A partial tear of the ACL can heal on its own if the knee is protected from further damage. Once fully avulsed or torn, the ACL is likely to require surgical repair or reconstruction.

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Forum discussions

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Peer-reviewed papers

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ACL injury
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