Posteromedial corner injury of the knee

Last revised by Bálint Botz on 23 May 2021

Posteromedial corner injury of the knee is a readily identifiable but frequently underappreciated injury on imaging. Importantly, it can result in increased stress on the cruciate ligaments and can result in anteromedial rotatory instability (AMRI) of the knee.

These injuries are frequently seen in athletes and are usually sustained with the knee in valgus. Physical examination may reveal tenderness along the medial joint line. The anterior drawer test with the tibia held in external rotation is used to evaluate for anteromedial rotatory instability. 

The structures that comprise the posteromedial corner (PMC) are located between the posterior margin of the tibial collateral ligament and medial border of the posterior cruciate ligament:

Up to 88% of injuries can be associated with a cruciate ligament injury, overwhelmingly the ACL 1.

May show non-specific findings, such as a lipohemarthrosis. A fracture of the medial tibial corner may be seen. Weight-bearing views can reveal a valgus deformity.

MRI is the investigation of choice, as it can readily demonstrate all components of the PMC:

Whether or not surgical intervention is offered depends on the presence of knee instability and concurrent cruciate or other ligamentous injuries. Surgical approaches vary with either surgical repair or reconstruction.

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Cases and figures

  • Case 1
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  • Case 2
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  • Case 3
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  • Case 4: with ACL tear
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  • Case 5: posterior oblique ligament injury
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