Semimembranosus tenosynovitis: Diagnosis and management of a commonly missed cause of posteromedial knee pain.

Background: In orthopedic and sports medicine literature there is minimal information regarding accurate diagnosis and the treatment options for tenosynovitis of the distal semimembranosus tendon. After reviewing the literature, the authors question both the etiology and treatment of this condition. Previous descriptions have associated the condition primarily with the endurance athlete but we have noted multiple cases in which this is a condition common to the 'sprinter' as well. There has been very little mention of this condition in recent literature but the most recent complete description of operative treatment for this condition recommends both tendon transfer and concomitant arthroscopy. We propose this condition is akin to De Quervain's tenosynovitis of the knee, with sensitive and specific signs on physical examination.
Methods: We describe a case series of six cases (five patients), that underwent open surgical release for semimembranosus tenosynovitis. The anatomy and the treatment options for the condition are also discussed.
Results: At a follow-up period of 18-64months, all cases showed improvement in the Tegner activity score following surgical release.
Conclusion: Diagnostic confusion can be decreased with more modern diagnostic imaging modalities than those described in the literature. The authors outline an alternative operative approach significantly decreasing surgical complexity and therefore post-operative morbidity. What is known about this subject: This is a rare condition and the surgical treatment is seldom performed. What this study adds to existing knowledge: We describe the technique for surgical decompression and reveal positive results at medium term follow-up.
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