Ultrasonography of the tibialis posterior tendon in rheumatoid arthritis

This work was carried out to assess the frequency of frank rupture of the tibialis posterior tendon (TPT) in RA and to determine if other pathology in the tendon can be correlated with foot deformity.Clinical, radiographic and ultrasonographic signs of TPT pathology were assessed bilaterally in 28 patients with RA hindfoot involvement. The degree of hindfoot pain, the single-heel-rise test and the tibiocalcaneal angle were assessed clinically. The talometatarsal angle was measured on lateral weight-bearing radiographs. Tendon continuity and thickness were noted on sonography, both in the study group and in a control group of 14 patients.The TPT was significantly thinner in those rheumatoid patients with an abnormal single-heel-rise test when compared those patients with a normal test (P<0.001) and to the control group (P<0.001). The mean thickness in patients with an abnormal test was 1.6 mm, in patients with a normal test it was 2.3 mm and in the controls it was 1.9 mm. In the rheumatoid group thinning of the tendon was significantly correlated (r = -0.33, P<0.05) with heel valgus as assessed by the tibiocalcaneal angle. It was also significantly correlated (r = 0.31, P<0.05) with pes planus as assessed by the talometatarsal angle. Only one case of frank rupture or the TPT was identified. There were also significant correlations between TPT thickness and patient age, disease duration and steroid therapy, such that tendon attenuation was associated with increasing age, longer disease and steroid usage. There was no association between TPT thickness and the degree of hindfoot pain.TPT attenuation in RA is associated with heel valgus and pes planus. These findings are consistent with the hypothesis that rheumatoid tenosynovitis causes tendon attenuation and dysfunction, so contributing to hindfoot deformity. Frank rupture of the TPT is a rare event in RA.