Ultrasonographic examination of the posterior tibial tendon

The posterior tibial tendons (PTTs) of 16 patients with PTT dysfunction and 10 age-matched healthy subjects were examined ultrasonographically, using a 10-MHz linear-array transducer. Normal PTTs appeared hyperechoic (more echogenic) and oval, with an average diameter of 7.8 mm x 3.7 mm at the medial malleolar level. Degenerated PTTs appeared hypoechoic (less echogenic) and swollen (9.8 mm x 5.0 mm). Peritendinitis presented as a hypoechoic rim on the longitudinal sonogram (along the long axis of the tendon) and a 'target sign' (hyperechoic central structure with a hypoechoic halo) on the transverse sonogram (at the right angle to the long axis of the tendon). Complete rupture of the PTT revealed an empty tibial groove at the level of the medial malleolus on the transverse sonogram and a wavy fibril pattern over the distal end on the longitudinal sonogram. Compared with the operative findings or the results of the magnetic resonance imaging, ultrasonography was sensitive and specific in diagnosing tenosynovitis and complete rupture of the PTT.