Magnetic resonance imaging appearances of the capsulo-osseous layer of the iliotibial band and femoral attachments of the iliotibial band in the normal and pivot-shift ACL injured knee

BACKGROUND: Biomechanical evidence suggests that the anterolateral structures of the knee may be important restraints against anterolateral rotatory instability (ALRI) in the setting of anterior cruciate ligament (ACL) injury. OBJECTIVE: To describe the anatomy and presence of injury of the capsule-osseous layer of the iliotibial band (CITB), the iliotibial band, and its deep distal femoral attachments in patients with a ‘normal’ knee (no pivot-shift bone marrow edema (BME) pattern) and patients with a pivot-shift BME pattern indicative of a pivot-shift injury associated with ACL tears. METHODS: Group 1: 20 consecutive patients with no MRI evidence of pivot-shift injury and group 2: 20 consecutive patients with a pivot-shift BME pattern on MRI were identified. Retrospective consensus analysis of the anatomy and appearances of the CITB and the ‘proximal’ and ‘epicondylar’ distal femoral attachments of the ITB was performed for each MRI by two experienced musculoskeletal radiologists. RESULTS: The positive predictive value (PPV) of CITB injury for pivot-shift ACL injury was 74%, negative predicted Value (NPV) was 80%. The PPV for injury of the ‘proximal’ ITB femoral attachment with pivot-shift ACL injury was 93%, NPV was 84%. The PPV for ‘epicondylar’ iliotibial femoral attachment injury was 62%, NPV was 45%. CONCLUSIONS: Injury of the CITB and ‘proximal’ deep femoral attachments of the ITB are good markers for ACL injury even in the absence of a Segond fracture and should be evaluated on all MRIs as they may prove important in the further management of ALRI.