The foot pad in rheumatoid arthritis measurement and possible effects on foot disability

The human foot pad is essential in buffering stress and strain during ambulation. Foot pad atrophy has been associated with foot pain, limping gait, callous formation, and foot ulcers. We report a method to measure foot pad thickness and have investigated its measurement reliability. Two podiatrists independently and bilaterally measured fore and rear foot pads on lateral view radiographs of weight bearing for 78 patients with rheumatoid arthritis. The intrarater coefficient on the fore and rear foot pads was 0.90 or higher, whereas the interrater reliability ranged from 0.73 to 0.92. These results suggest foot pad measurement is simple, practical, and reproducible for measuring foot pad atrophy. This measurement will help identify patients at risk for foot pain and/or ulceration so that appropriate orthotics and soft tissue supplements may be recommended.