Age- and Sex-Related Normative Data for the Foot Function Index in a German-Speaking Cohort

Background: Despite increasing popularity of the Foot Function Index (FFI), normative values are still unavailable for this self-administered score. This study was designed to generate age- and sex-related normative values for the FFI-total and for both subscales FFI-pain and FFI-disability. Methods: We used the cross-cultural adapted and validated German version of the FFI to generate a data pool using the results of 625 individuals, including staff and visitors to our hospital and excluding persons scheduled for foot surgery or in after-treatment. Results: Mean values for FFI-total were calculated: 15.3 points (95% confidence interval [CI], 13.3-16.9), 14.9 points for FFI-pain (CI, 13.3-16.5), and 15.6 for FFI-disability (CI, 13.8-17.4). Results showed higher values for FFI-total, FFI-pain, and FFI-disability for individuals older than 40 years. In general, normative values showed a tendency for higher values with age. A slightly inconsistent distribution over different age groups with a peak for individuals in their 40s and 50s was observed, especially for FFI-pain. Men had better scores than women. Individuals with previous surgery showed lower scores in their respective score. Conclusions: Our data calculated normative values for a German-speaking cohort for FFI-total as well as for both subscales FFI-pain and FFI-disability. Our data quantified the increase of FFI-total, FFI-pain, and FFI-disability normative values with age but also showed a slightly inconsistent distribution of normative values over all age groups. We demonstrated higher normative values for women and slightly higher normative values for individuals with previous foot or ankle surgery. Level of Evidence: II, prospective comparative study