To evaluate the clinical findings of a complete radial rupture of the meniscal root ligament of the medial meniscus posterior horn.

From April, 2004 to December, 2004, nineteen patients (mean age, 56.5 years old) who were diagnosed with a medial root ligament rupture of the medial meniscus posterior horn during an arthroscopic treatment were enrolled in this study. The clinical findings, physical examinations, and the radiological and arthroscopic findings were analyzed retrospectively.

Thirteen out of the nineteen cases had tenderness of the knee without specific trauma. The preoperative physical examination revealed posteromedial joint line tenderness in fifteen cases. A medial joint line protrusion with direct tenderness was observed in six cases (31.5%) and a positive McMurray test was observed in seventeen cases (89.5%). MRI was carried out in sixteen patients. All sixteen patients were diagnosed with a rupture of the meniscal root ligament using the author's diagnostic MRI criteria.

Non-traumatic pain and posteromedial joint line tenderness in patients in their sixth decade are indications of a rupture of the meniscal root ligament of the medial meniscus posterior horn. Confirmation using MRI and arthroscopy is important for making a diagnosis.