Foot and ankle functions and deformities focus on posterior tibial tendon dysfunction using magnetic resonance imaging in patients with rheumatoid arthritis

Posterior tibial tendon dysfunction (PTTD) affects the support of the medial longitudinal arch and stability of the hindfoot. The purpose of this study was to assess the relationships of PTTD with foot and ankle functions and foot deformities in patients with rheumatoid arthritis (RA).

A total of 129 patients (258 feet) who underwent magnetic plain and contrast-enhanced magnetic resonance imaging were enrolled in this study. Positive magnetic resonance imaging findings were defined as tenosynovitis and incomplete and complete rupture of the posterior tibial tendon. Foot and ankle functions were assessed using the Japanese Society for Surgery of the Foot standard rating system for the RA foot and ankle scale (JSSF-RA) and self-administered foot evaluation questionnaire. Plain radiographs were examined for the hallux valgus angle, first metatarsal and second metatarsal angle, lateral talo-first metatarsal angle, and calcaneal pitch angle.

PTTD was associated with motion in the JSSF-RA (p = .024), activities of daily living in JSSF-RA (p = .017), and pain and pain-related factors in the self-administered foot evaluation questionnaire (p = .001). The calcaneal pitch angle was significantly lower in the feet with PTTD than in those without PTTD (median: 16.2° vs. 18.0°; p = .007).

The present study shows that PTTD was associated with foot and ankle functions and flatfoot deformity. Thus, a better understanding of PTTD in patients with RA is important for the management of foot and ankle disorders in clinical practice.