MR-IMAGING OF POSTERIOR TIBIAL TENDON DYSFUNCTION

OBJECTIVE. The purpose of this study was to describe the MR findings o f posterior tibial tendon dysfunction. MATERIALS AND METHODS. MR image s and medical records were reviewed for 11 patients with surgically pr oven posterior tibial tendon abnormalities (i.e., tears or tenosynovit is) and for six patients with clinical evidence of posterior tibial te ndon dysfunction. Our study group included 16 women and one man from 3 7 to 70 years old (mean, 53.5 years old). MR examinations used T1-weig hted and T2-weighted spin-echo sequences in the oblique axial and sagi ttal planes. RESULTS. Abnormal MR findings were observed in all 17 pat ients. The spectrum of MR abnormalities included fluid in the tendon s heath of a normal tendon interpreted as isolated paratenonitis (tenosy novitis, n = 3); tendon thickening and surrounding fluid with normal t endon signal interpreted as tendinosis (degeneration, n = 1); tendon t hickening with increased linear or heterogeneous intrasubstance signal interpreted as partial tear (n = 11); tendon discontinuity with fluid -filled tendon sheath interpreted as complete rupture (n = 2). In 11 p atients, the posterior tibial tendon was explored at surgery. In these patients, MR imaging accurately showed two cases of isolated parateno nitis, one case of tendinosis, four partial tears, and two complete ru ptures. In the remaining two patients, the presumed MR diagnosis did n ot correlate very closely with the surgical findings: one patient with isolated paratenonitis shown by MR imaging had tendinosis found at su rgery; however, the surgery in this patient followed the MR examinatio n by 10 months, a time during which degeneration might have occurred. The other patient had an MR diagnosis of partial tear, which was not f ound at surgery; however, tendon degeneration was severe and a small t ear not reaching the tendon surface could have been missed at inspecti on. MR imaging characteristics of severe tendinosis and partial tear m ay overlap. CONCLUSION. MR imaging is effective for detecting abnormal ities related to posterior tibial tendon dysfunction. Familiarity with the appearance of these changes facilitates accurate characterization .