The posteromedial corner of the knee: medial-sided injury patterns revisited.

BACKGROUND Medial-sided knee injury patterns have been poorly defined in the available literature. The lack of definition can be attributed to the differing anatomic perspectives of physician authors and the functional significance they assigned to the posteromedial structures of the knee. HYPOTHESIS Many so-called medial collateral ligament injuries can involve significant damage to the posteromedial corner structures that may not be appreciated. STUDY DESIGN Retrospective cohort study. METHOD The authors reviewed the charts of 93 patients (93 knees) with operatively treated isolated and combined medial-sided knee injuries and described the associated medial injury patterns. RESULTS Ninety-nine percent of the knees were found to have an injury of the posterior oblique ligament. In the series, 70% of the knees also had an injury of the semimembranosus capsular attachment, and 30% were found to have complete peripheral detachment of the meniscus. Injury to the posterior oblique ligament was the common injury, but other sites of disruption capable of disabling this dynamic meniscocapsular complex were present. CONCLUSIONS Before assigning function to the various posteromedial structures of the knee, we must better define medial-sided injury patterns, the purpose of the current work. From this review of medial-sided injuries in this series of patients, the authors have come to realize that a subgroup of these knee injuries involves injuries to the posteromedial structures that are under-appreciated.