Influence of foot characteristics on the site of lower limb osteoarthritis

Background. Foot structure and range of motion have been linked to lower limb musculoskeletal injuries in sports medicine,(11,14,41) and recently there have been attempts to establish a connection between the foot and lower limb osteoarthritis (OA).(19,13) Considering the fact that OA of the knee and hip are the most important causes of pain and disability in older people,(12,15) it is surprising that there has been no research comparing the foot types of those with knee OA and those with hip OA. To evaluate an apparent difference in the feet and gaits of patients with hip OA and medial compartment OA of the knee that was noted during routine clinical assessment, a prospective observation study was undertaken. Methods: The study included patients with OA either of the hip or the medial compartment of the knee and a control group of healthy subjects. There were 60 in each group determined by sample size calculation. The groups were matched for age and gender. Dorsiflexion and plantarflexion of the ankle, calcaneal angle, and navicular height in both sitting and standing were measured. Results were analyzed by ANOVA and linear regression analysis. Results: There were significant differences among all three groups, particularly in ankle dorsiflexion (p < 0.001) and calcaneal angle (p < 0.001). Conclusions: Differences in foot type between patients with OA of hip and knee were confirmed. These two groups also were different from the control group of healthy subjects. The lack of ankle dorsiflexion and high arches of patients with OA of the hip contrasted with the ample dorsiflexion and flatfeet of patients with OA of the knee.