Tenosynovial fluid as an indication of early posterior tibial tendon dysfunction in patients with normal tendon appearance.

Patients with stage 1 PTT dysfunction displayed greater volumes of tendon-sheath fluid than those with other causes of medial ankle pain and compared with asymptomatic controls. A threshold maximum fluid width greater than or equal to 9 mm distinguishes those with PTTD. An association between tendon sheath fluid distension and the clinical diagnosis of stage 1 posterior tibial tendon disease in the setting of no MRI-detectable intra-substance tendon pathology may allow for differentiation of medial ankle pain from other sources and may allow for early intervention aimed at preventing progressive PTTD. The level of evidence was prognostic (level III).