Regionalised centre of pressure analysis in patients with rheumatoid arthritis

Background Rheumatoid arthritis patients alter their gait pattern to compensate for painful foot symptoms. The centre of pressure may be a useful indicator of these altered loading patterns. Our purpose was to undertake a comparison of the regionalised duration and velocity of the centre of pressure between rheumatoid arthritis patients with foot impairments and healthy able-bodied adults. Methods The progression of the centre of pressure through the foot, heel, midfoot, forefoot and toe regions was measured using an EMED-ST pressure platform. Patients walked at self selected cadence. Variables analysed were the average and maximum velocity and the duration of the centre of pressure (as % stance). Results In comparison with able-bodied adults, rheumatoid arthritis patients had a statistically significant decrease in the average velocity of the centre of pressure in the total foot (P < 0.001), heel (P = 0.001) and midfoot (P < 0.001) regions. The maximum velocity of the centre of pressure was slower in rheumatoid arthritis patients in only the midfoot region (P = 0.002). During stance, the duration of the centre of pressure was longer in the midfoot (P < 0.001) and shorter in the forefoot (P = 0.001) in the rheumatoid arthritis patients. Interpretation Alteration of the foot loading patterns in patients with rheumatoid arthritis can be characterised by changes to the centre of pressure patterns. Off-loading the painful and deformed forefoot was a characteristic feature in this patient cohort.