Posteromedial Meniscocapsular Ramp Lesions of the Knee: An MRI-Focused Review, From the <i>AJR</i> Special Series on Critical Anatomy

Injuries of the posteromedial meniscocapsular junction encompass a spectrum of injuries at or near the posteromedial meniscocapsular junction. These so-called ramp lesions have become increasingly well recognized, defined, and understood. Such injuries range in severity from perimeniscal edema-like signal to tears at or near the meniscocapsular junction, with or without meniscocapsular separation. Since the term's introduction in 1998, the definition of a ramp lesion has evolved to include not only tears of the perimeniscal (meniscocapsular and meniscotibial) attachments but also tears of the peripheral third of the posterior horn of the medial meniscus (PHMM). Radiologists should seek to accurately recognize the presence of a ramp lesion on MRI, to help guide orthopedic surgeons in inspecting the posteromedial meniscocapsular region at the time of arthroscopy. This Special Series Review provides an imaging-focused description of ramp lesions of the knee. The article presents pertinent anatomy of the posteromedial meniscocapsular junction, pathogenesis underlying occurrence of ramp lesions, criteria for diagnosing these lesions on MRI, potential pitfalls, and observed injury patterns. The goals of treatment are additionally discussed, highlighting the rationale behind use of different treatment approaches for stable and unstable ramp lesions.