The posteromedial corner (PMC) is the region towards the back of the knee on the inner side.
Page updated January 2024 by Dr Sheila Strover (Clinical Editor)
Key structures of the 'neglected corner' of the knee
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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Quote from peer-reviewed paper:
"Injury [to the posteromedial corner] is common and compromise of the medial restraints may result in the development of valgus and rotatory laxities, increased forces on the cruciate ligaments or persistent pain and dysfunction....[and] determining which higher-grade PMC injuries warrant surgical repair or reconstruction can be challenging...."
Citation: Chahla J, Kunze KN, LaPrade RF, Getgood A, Cohen M, Gelber P, Barenius B, Pujol N, Leyes M, Akoto R, Fritsch B, Margheritini F, Rips L, Kautzner J, Duthon V, Togninalli D, Giacamo Z, Graveleau N, Zaffagnini S, Engbretsen L, Lind M, Maestu R, Von Bormann R, Brown C, Villascusa S, Monllau JC, Ferrer G, Menetrey J, Hantes M, Parker D, Lording T, Samuelsson K, Weiler A, Uchida S, Frosch KH, Robinson J. The posteromedial corner of the knee: an international expert consensus statement on diagnosis, classification, treatment, and rehabilitation. Knee Surg Sports Traumatol Arthrosc. 2021 Sep;29(9):2976-2986. doi: 10.1007/s00167-020-06336-3. Epub 2020 Oct 26. PMID: 33104867; PMCID: PMC7586411.
Diagnosing injury to the posteromedial corner
Clinical examination should include valgus stress testing - supporting the lower leg at the ankle while testing the 'give' when pushing the knee inwards.
The dial test and anteromedial drawer tests examine for laxity in rotation.
MRI should support the clinical examination initially if the medial collateral ligament is ruptured. Valgus stress X-rays may be useful in the assessment of more chronic injuries.
Management of posteromedial corner injuries
Isolated partial ruptures of the superficial medial collateral ligament are usually treated conservatively with a range-of-motion brace.
Indications for operating on acute injuries include -
- both tibial and femoral bony avulsions, where the ligaments have been ripped loose from their bony attachments together with a piece of the bone
- intra-articular entrapment, where damaged soft tissue gets caught up in the joint
- a “Stener lesion” where soft tissue gets sandwiched in the wrong place and prevents the MCL from re-attaching to the tibia bone
Forum discussions
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Footballers getting to grips with the issues around MCL injury.
Relevant material -
Peer-reviewed papers -
- 2015 - Posteromedial Corner of the Knee: The Neglected Corner - Authors: Lundquist et al. - summarised by Dr Sheila Strover (Clinical Editor)
- 2016 - Posterior meniscal root injuries - Authors: Moatshe G et al. - summarised by Dr Sheila Strover (Clinical Editor)