Pathogenesis of the segond fracture: Anatomic and MR imaging evidence of an iliotibial tract or anterior oblique band avulsion

PURPOSE: To demonstrate the normal anatomy of the stabilizing structures of the lateral aspect of the knee and to investigate pathogenesis of the Sego nd fracture, with emphasis on the iliotibial tract (ITT) and anterior obliq ue band (AOB) of the fibular collateral ligament. MATERIALS AND METHODS: Dissection of the region of the AOB, ITT, and latera l capsular ligament was performed in three cadaveric knees, with placement of gadopentetate dimeglumine-filled tubes along their course and tibial ins ertions. These knees, in addition to three nondissected knees, were studied with magnetic resonance (MR) imaging by using standard and specialized obl ique planes. Specimen sectioning provided anatomic Correlation. Retrospecti ve review of radiographs and MR images in 17 patients with acute Segond fra ctures was performed, and the relationship between the fragment and the dem onstrated lateral supporting structures of the knee was noted. RESULTS: Anatomic dissection and MR imaging of the cadaveric knees demonstr ated a broad tibial insertion of the ITT, with fibers extending posterior t o the Gerdy tubercle. A firm band of tissue, the AOB, extended from the fib ular collateral ligament to the midportion of the lateral tibia, the typica l site of a Segond fracture. The lateral capsular ligament proved to be a m ere thickening of the capsule, inserting at the lateral tibia. Clinical ana lysis of acute Segond fractures confirmed the frequent attachment of the IT T and AOB to the avulsed fragment. CONCLUSION: Anatomic and clinical findings suggest that fibers of the ITT a nd AOB are important factors in the pathogenesis of the Segond fracture.