Orthotic management of plantar pressure and pain in rheumatoid arthritis

Objective. To investigate the effectiveness of foot orthoses in the management of plantar pressure and pain in subjects with rheumatoid arthritis. Design. A repeated measures study in which the independent variable was orthosis design. Dependent variables, including pressure, gait and pain parameters, were examined using analysis of variance and correlation statistics. Background. The aim of orthotic management of the rheumatoid foot is to relieve metatarsalgia through the reduction of metatarsal head pressure. Few studies have investigated the relative effectiveness of different orthosis designs. To date, no studies have examined the relationship between plantar pressure and second metatarsal head pain in rheumatoid arthritis subjects. Methods. Twelve rheumatoid arthritis subjects with foot involvement and second metatarsal head pain were tested. Four styles of foot orthosis (prefabricated, standard custom moulded, custom with metatarsal bar, custom with metatarsal dome) were compared to a shoe only control. An EMED Pedar system was used to measure plantar pressure during repeated trials of comfortable cadence walking and quiet standing. Reports of subjective pain were recorded for each orthosis as were orthosis preferences. Results. All orthoses significantly reduced pressure beneath the first and second metatarsal heads compared to the shoes only control. The custom moulded orthosis with metatarsal dome was the most effective orthosis for reducing subjective ratings of pain. A significant correlation (r=0.562) was found between ratings of pain and average pressure beneath the second metatarsal head. Conclusions. Results from this study suggest that average pressure measurement may be a useful indicator in the management of metatarsalgia in RA. Further study is required to improve understanding of the relationship between rheumatoid foot mechanics and pain.