Forefoot joint damage, pain and disability in rheumatoid arthritis patients with foot complaints: the role of plantar pressure and gait characteristics

Objective. To assess (i) the relationship between forefoot joint damage and foot function (expressed as gait and pressure parameters), (ii) the relationship between foot function and pain, and (iii) the relationship between foot function and disability in patients with foot complaints secondary to rheumatoid arthritis (RA). Methods. Sixty-two patients with RA-related foot complaints were included. Measurements of joint damage, gait characteristics, plantar pressure, pain and disability were obtained. Data were analysed using descriptive and correlational techniques. Results. Joint damage on radiographs of the forefoot correlated significantly with forefoot pressure (r = 0.296, P = 0.020). Further investigation of the metatarsophalangeal joints (MTPs) showed joint damage to correlate significantly with peak pressure and pressure-time integral (PTI) of MTP1 and MTP4. A significant correlation between PTI under the forefoot and barefoot pain was found (r = 0.290, P = 0.022). Gait parameters (total contact time and the duration of heel loading) and disability, measured with the Foot Function Index, were significantly correlated (r = 0.315, P = 0.013 and r = 0.266, P = 0.037, respectively). Conclusion. Forefoot joint damage in the rheumatoid foot is related to increased pressure under the forefoot, especially pressure under the first and fourth MTP joints. High forefoot pressure is associated with pain during barefoot walking. A prolonged stance phase and delayed heel lift are related to disability in daily activities.