KSSTA - 2026-09-16 - Journal Article; Review
Current concepts in isolated and combined injuries of the medial collateral ligament complex-Part I: Anatomy, biomechanics, clinical and radiological examination of the medial collateral ligament of the knee.
Runer A, Amis A, Smigielski R, Herbst E, Kittl C, Wierer G, Bouguennec N, Cristiani R, Hoser C, Abermann E, Willinger L, D'Ambrosi R, Senorski EH, Getgood A, Musahl V, Ball S, Williams A, Moatshe G, Siebenlist S, Strauss M, Lind M, Herbort M, Samuelsson K, Fink C, Robinson J
Topics
Key Takeaway
The dMCL is the primary restraint to external tibial rotation at low flexion angles and is the key driver of anteromedial rotatory instability (AMRI), a diagnosis requiring combined valgus stress at 20°, anteromedial drawer at 20°, and anterior tibial translation at 90° with tibia in neutral and external rotation.
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Summary
This current concepts review synthesizes anatomy, biomechanics, and diagnostic approaches for isolated MCL and combined ACL-MCL injuries, with particular focus on the distinct roles of the sMCL, dMCL, and POL. The sMCL is the primary valgus restraint and resists anterior tibial translation at higher flexion with external rotation, while the dMCL governs external tibial rotation at low flexion angles and is central to AMRI. The authors recommend bilateral, structure-specific clinical examination including anteromedial drawer testing and valgus stress at 20° to accurately characterize AMRI, cautioning against overreliance on MRI alone for injury severity grading.
Key Limitation
As a Level V expert review without a systematic search strategy or pooled outcome data, the clinical examination recommendations lack validation against arthroscopic or intraoperative findings as a reference standard.
Original Abstract
Injuries involving the medial collateral ligament (MCL), or combined injuries to both the anterior cruciate ligament (ACL) and MCL, are common and present considerable diagnostic and therapeutic challenges. Better understanding of MCL anatomy and biomechanics, especially in combined ACL-MCL injuries, has driven the need for updated clinical examination and treatment approaches. The MCL complex comprises the superficial MCL (sMCL), deep MCL (dMCL), and the posteromedial complex (PMC), which includes the posterior oblique ligament (POL). Additional contributors to medial knee stability include the AMR and dynamic structures such as the semimembranosus, semitendinosus, and gracilis tendons. Biomechanically, the sMCL serves as the primary restraint against valgus loading and resists anterior tibial translation, particularly at higher degrees of knee flexion with external tibial rotation. The dMCL functions as a key stabiliser against external tibial rotation at low flexion angles and plays a significant role in anteromedial rotatory instability (AMRI), while the PMC/POL primarily limits internal tibial rotation. Accurate diagnosis requires an integrated approach, including thorough patient history, detailed physical examination, magnetic resonance imaging (MRI), and selective use of stress tests. Clinical assessment remains essential, as overreliance on imaging alone may misrepresent injury severity. Evaluation of medial-sided structures should be performed bilaterally and for each structure separately, based on their distinct biomechanical roles. The POL should be evaluated in full patient-specific knee extension. Assessment for AMRI should involve testing both valgus laxity at 20° of knee flexion, anteromedial drawer at 20° and anterior tibial translation at 90° with the tibia in neutral and then externally rotated. Findings of increased anterior tibial translation accompanied by excessive external tibial rotation relative to the contralateral side strongly indicate AMRI. This current concept article reviews the current literature and provides evidence-based recommendations to develop guidance and optimize treatment strategies for isolated MCL injuries and combined MCL-ACL injuries
LEVEL OF EVIDENCE
Level V.