Arthroscopic Dissection of the Distal Semimembranosus Tendon: An Anatomical Perspective on Posteromedial Instability and Ramp Lesions

Ramp lesions are increasingly recognized as a hallmark of posteromedial knee instability. Although the precise mechanisms through which these lesions occur is not completely understood, the distal semimembranosus complex has been implicated in their pathogenesis due to its attachment to the posterior horn of the medial meniscus (PHMM). Arthroscopic dissection of the distal semimembranosus tendon, and the application of traction to it, results in posterior translation of the PHMM and stretching of the meniscocapsular region. This demonstrates a mechanism through which ramp lesions can occur. Furthermore, the subsequent open dissection highlights the complex anatomical relationships of the distal semimembranosus tendon complex, particularly its tensioning effect on the posterior oblique ligament. The clinical relevance of this is that when a ramp lesion occurs, it is likely to be part of a spectrum of posteromedial injury and it should be considered a hallmark of posteromedial instability rather than an isolated meniscocapsular injury.