VALIDATION DATA

Internal consistency (Cronbach’s α) in the original study of 100 patients undergoing hallux valgus surgery for each subscale was as follows: walking/standing, 0.92; foot pain, 0.86; and social interaction, 0.73. Similar results were subsequently observed in the translated versions, with the range of Cronbach’s α for each subscale as follows: walking/standing, 0.77 to 0.99; pain, 0.78 to 0.98; and social interaction, 0.70 to 0.99

Test‐retest reliability (intraclass correlation coefficients) in 257 patients undergoing various foot and ankle surgical procedures for each subscale has been reported as follows: walking/standing, 0.96; pain, 0.94; and social interaction, 0.92. Across the various language translations, test‐retest reliability has been reported as follows: walking/standing, 0.82 to 0.97; pain, 0.81 to 0.98; and social interaction, 0.82 to 0.96 

Content validity was originally examined by using exploratory, semistructured interviews conducted with 10 patients who were attending hospital surgical outpatient clinics for hallux valgus, followed by patients completing and commenting on the MFPDI. This resulted in the rewording of some MFPDI items, the addition of two items specifically addressing pain severity and pain frequency at nighttime, and the increasing of the response categories from three to five per item