POSTERIOR TIBIAL TENDON DYSFUNCTION - SECONDARY MR SIGNS

We evaluated four potential secondary magnetic resonance imaging signs to aid in clinical diagnosis of posterior tibial tendon (PTT) tears. Seventy-one ankles (25 PTT tears and 46 controls) were evaluated for t he following secondary signs: (1) PTT sheath fluid, (2) a distal tibia l spur located just anterior to the PTT, (3) unroofing of the talus, a nd (4) ''bone bruise''-like medullary lesions. Two musculoskeletal rad iologists rated their confidence using a scale and were compared for l evel of agreement. The presence of PTT sheath fluid had modest specifi city and fair to moderate sensitivity. Tibial spurring and unroofing o f the talus had excellent specificity and fair sensitivity. Bone bruis e-like lesions were commonly seen in cases and controls. Examination o f divergence of opinion between the two radiologists revealed pitfalls in interpretation of PTT sheath fluid and bone bruise-like lesions, w hich were commonly the result of adjacent vessels and inhomogeneous fa t saturation, respectively. We conclude that secondary signs of PTT te ars with high specificities include unroofing of the talus, tibial spu rring, and PTT sheath fluid.