To assess the relationship between disease duration and foot function (expressed as pressure and gait parameters), foot pain and disability, in patients with foot complaints secondary to rheumatoid arthritis (RA).
Sixty-two patients with RA-related foot complaints were included. Disease duration was defined as the time since RA was diagnosed. A pressure platform was used to measure both pressure parameters (i.e. pressure-time integrals and peak pressures in the forefoot) and gait parameters (i.e. total loading time and loading time in different foot regions). In addition, measurements of foot pain, disability (i.e. walking time and self reported disability), forefoot joint damage and disease activity were obtained. Data were analysed using partial correlations (Spearman), correcting for age.
Disease duration was significantly correlated with the maximum pressure-time integral (PTI) measured under the forefoot (r = 0.330, p = 0.01). Disease duration was also significantly correlated with gait parameters, i.e. total loading time (r = 0.265, p = 0.04), duration of heel loading and duration of toe loading (r = 0.326, p = 0.01 and r = -0.288, p = 0.03 respectively), and walking time (r = 0.297, p = 0.02). Disease duration did not correlate with self-reported foot pain or disability.
In patients with RA-related foot complaints, longer disease duration is associated with impaired foot function and reduced walking speed. These findings are interpreted as an alteration in pressure distribution and gait pattern during the course of disease, with a shift from a heel-to-toe roll-over process to a more shuffling gait.