To evaluate the efficacy of custom foot orthoses for the management of painful rearfoot valgus in patients with rheumatoid arthritis (RA).
Patients were randomized to receive custom-manufactured rigid carbon graphite foot orthoses (RA-orthosis) or enter a control group (RA-control) receiving no orthotic intervention. Three-dimensional (3D) kinematics were measured at the ankle joint complex (AJC) using an electromagnetic tracking (EMT) system under barefoot, shod, and orthosis walking conditions. Previously established normal 3D kinematic data were used to descriptively compare motion patterns in both RA groups and statistical analyses were performed on integrals of motion-time for each axis of rotation from data collected at baseline, 3, 6, 12, 18, 24, and 30 months.
Compared with healthy control subjects, all patients with RA demonstrated excessive subtalar joint eversion motion through the stance phase of gait (p < 0.0001) coupled with excessive internal leg rotation (p < 0.0001). Custom-manufactured orthoses significantly reduced eversion through stance (p = 0.009) and re-established equilibrium of motion relative to neutral joint position. Correcting the frontal plane component of the deformity did not lead to a significant reduction in internal leg rotation (p = 0.294). The devices had no effect on tibiotalar dorsiflexion/plantarflexion (p = 0.960). Prospectively, the rigid orthoses maintained and then improved the reduction in cumulative subtalar eversion motion (p < 0.0001). Minimal changes in cumulative subtalar component eversion and internal leg rotation were recorded for both RA groups when walking barefoot but the effect was significantly less for the RA-control group. From 12 months onwards, internal leg rotation started to decrease, suggesting re-coupling of motion, but the overall motion pattern remained abnormal in comparison with normal reference values.
These results support the continuous use of custom-manufactured foot orthoses to correct deformity and optimize AJC function in RA patients with early painful deformity of the rearfoot.