Chronic plantar heel pain is principally associated with waist girth (systemic) and pain (central) factors, not foot factors: A case-control study

OBJECTIVE: To determine the independent associations of potential clinical, symptom, physical activity, and psychological factors with chronic plantar heel pain. U DESIGN: Case-control. U METHODS: We investigated associations by comparing 220 participants with chronic (more than 3 months in duration) plantar heel pain to 100 age- and sex-matched controls, who were recruited randomly from the electoral roll. Exposures measured were waist girth, body mass index, body composition, clinical measures of foot and leg function, physical activity via accelerometry, depression and pain catastrophizing, symptoms of prolonged morning stiffness anywhere in the body, and multisite pain. Data were analyzed using multivariable conditional logistic regression. U RESULTS: Waist girth (centimeters) (odds ratio [OR] = 1.06; 95% confidence interval [CI]: 1.03, 1.09), ankle plantar flexor strength (kilograms) (OR = 0.98; 95% CI: 0.97, 0.99), pain at multiple sites (pain at 1 other site: OR = 2.76; 95% CI: 1.29, 5.91; pain at 4 or more other sites: OR = 10.45; 95% CI: 3.66, 29.81), and pain catastrophizing status (none, some, or catastrophizer) (some: OR = 2.91; 95% CI: 1.33, 6.37; catastrophizer: OR = 6.79; 95% CI: 1.91, 24.11) were independently associated with chronic plantar heel pain. There were univariable but not independent associations with morning stiffness, first metatarsophalangeal joint extension range of motion, depression, and body mass index. There were no significant associations with physical activity or body composition (bioelectrical impedance analysis). U CONCLUSION: Waist girth, ankle plantar flexor strength, multisite pain, and pain catastrophizing, but not foot-specific facto F42 rs, were independently associated with chronic plantar heel pain. Of these 4 factors, 3 (waist girth, multisite pain, and pain catastrophizing) were central or systemic associations.