Foot disorders associated with overpronated and oversupinated foot function: the Johnston County osteoarthritis project.
BACKGROUND
The occurrence of musculoskeletal foot disorders differs by race and obesity, and these disorders may be related to pronated (low arch) or supinated (high arch) foot structure. This cross-sectional analysis examined relationships of foot disorders and foot function by race and obesity in a community-based observational study of adults 50+ years old with and without osteoarthritis.


METHODS
Members of a prospective cohort study in North Carolina were included in this analysis (N = 1466, 67.2% women, 29.5% African American, mean age 68.5 years). Foot disorders were identified with a validated assessment tool, and each foot was categorized as overpronated, oversupinated, and referent using the center of pressure excursion index from foot pressure scans during normal-paced walking. Logistic regression models estimated associations between foot function and each foot disorder with age, body mass index (BMI), gender, and race as covariates.


RESULTS
Compared to referent, an overpronated foot was associated with hallux valgus (adjusted odds ratio [aOR] 1.36, 95% confidence interval [CI] 1.13-1.65) and overlapping toes (aOR 1.36, 95% CI 1.12-1.64), especially in the obese. An oversupinated foot was inversely associated with hallux valgus (aOR 0.85, 95% CI 0.74-0.97). An oversupinated foot was less likely to be associated with bunionettes among the obese and was more likely to be associated with plantar fasciitis in Caucasians.


CONCLUSION
Foot function was related to hallux valgus and overlapping toes, especially among the obese. In clinical patients as well as in the community of older adults, treatments for both the foot disorder and the pronated/supinated foot may be needed.


LEVEL OF EVIDENCE
Level II, comparative cohort study.