Biomechanical evaluation of foot pressure and loading force during gait in rheumatoid arthritic patients with and without foot orthosis.

Foot orthoses are commonly used in patients with rheumatoid arthritis (RA) to support the foot and relieve pain, however little is known about the biomechanical effects of in-shoe foot orthoses in reducing or redistributing high pressures and loading forces. The purpose of this study was to compare the foot pressures and loading forces during gait in rheumatoid arthritic patients and healthy subjects, and evaluate the biomechanical effects of the foot orthoses in the RA patients. Twelve female RA patients with foot pain in walking, all Steinbrocker class II, and 8 healthy women without foot pain were matched for age. Foot pressures and loading forces with and without orthoses were measured using the F-Scan program. The pressure distributions and loading forces were standardized by the body weight and compared, and the effects of the foot orthoses were evaluated. The foot orthoses of RA patients provided higher pressure reduction than those of the control group (3.00 +/- 0.38 g/cm2/BW and 3.29 +/- 0.29 g/cm2/BW respectively, p < 0.001). Similar redistribution of plantar pressures and loading forces were found between two groups but the RA patients had a greater change at the stance phase of gait (p < 0.0001). The foot orthosis produces greater pressure and loading force relief and redistribution in RA patients than in normal subjects.