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

The posteromedial corner (PMC) is the region towards the back of the knee on the inner side.

Posteromedial corner
The semimembranosus expansion (SME) is the expansion of the semimembranosus tendon, and inserts the femur, tibia and the medial meniscus. Other structures of the posteromedial corner include the posterior oblique ligament, the medial collateral ligament and the tendon of the medial head of the gastrocnemius muscle.

The neglected corner of the knee

Much recent attention has been paid by radiologists and surgeons to the posterolateral corner, but the posteromedial corner is often neglected during assessment of an injured knee.

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Instabilities from PMC injury

Disruption of the PMC can cause anteromedial rotational instability. Usually injury of the PMC occurs in association with anterior or posterior cruciate ligament tears. The key issue is that cruciate reconstructions may fail if the surgeon does not recognise and address the PMC instability.

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neglected corner
dark side of the knee

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Dr Sheila Strover (Editor)
BSc (Hons), MB BCh, MBA

See biography...

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