Fibular groove morphology and measurements on MRI: correlation with fibularis tendon abnormalities.

PURPOSE: Fibular (peroneal) groove morphology may influence fibularis tendon pathology, including tendinosis, tears, and luxation. The study goal was to evaluate the inter-reader agreement of morphologic characterization and measures of the fibular groove at two different levels on MRI and correlation with fibularis tendon pathology.

MATERIALS AND METHODS: 47 ankle MRIs in patients without lateral ankle pain were reviewed by two musculoskeletal radiologists. Fibular groove morphology and various measurements were assessed at both the level of the tibial plafond and 1 cm proximal to the tip of the lateral malleolus. Fibularis tendon pathology and other variants were also recorded. Intraclass correlation (ICC) and kappa statistic (κ) were applied to assess inter-observer agreement. Receiver operating characteristic (ROC) and area under the curve (AUC) analysis were performed to determine correlation between fibular groove morphometry and fibularis (peroneus) brevis tendon tears.

RESULTS: Between readers, there was fair-to-excellent agreement (ICC = 0.61-0.95) for performed fibular groove measurements and moderate-to-very good agreement for identification and description of fibular groove and fibularis tendon morphology and pathology and normal variants in this region (κ = 0.46-1), with the exception of fibular groove morphology at 1 cm proximal to the lateral malleolar tip (κ = 0.34). Individually, no measurement or description of pathology could discriminate between patients with or without fibularis brevis tendon tears except fibularis brevis tendinosis (AUC = 0.87 for reader 1).

CONCLUSION: There is overall moderate-to-excellent inter-reader agreement for various measurements and descriptors of fibular groove and fibularis tendon morphometry and pathology, including novel measurements introduced in this study.