Foot and Ankle Disability Index (FADI)
- Fysiobasen
- Sep 18
- 3 min read
The Foot and Ankle Disability Index (FADI) is a region-specific self-report tool developed to assess functional limitations related to foot and ankle injuries. The instrument was introduced by Martin et al. in 1999 and has since been widely used in both clinical practice and research to evaluate functional status in patients with foot and ankle problems.
FADI is considered the predecessor to the Foot and Ankle Ability Measure (FAAM). The two instruments are nearly identical, but FADI contains five additional items assessing pain (four questions) and sleep (one question). These were later removed from FAAM to improve psychometric properties, while the sports subscale was retained. The result was a more streamlined and clinically practical instrument.
Advantages and limitations
Advantages:
High sensitivity and specificity: Hale and Hertel【1】 demonstrated that FADI reliably identifies functional limitations in individuals with chronic ankle instability (CAI).
Relevant for athletes: Eechaute et al.【2】 concluded that FADI and FAAM are the most appropriate tools for evaluating athletes with CAI.
Responsive to rehabilitation: FADI can detect clinically significant improvements in function following rehabilitation programs.
Limitations:
Less suitable for elderly patients: Due to the activity level of the questions, FADI may be less relevant for those with significantly reduced mobility.
Complex scoring: While the instrument provides detailed results, the scoring system can be time-consuming for clinicians without prior experience.
Structure of the instrument
FADI consists of 34 items divided into two subscales:
FADI (26 items): Covers pain (4 items) and daily activities (22 items).
FADI Sport (8 items): Measures more complex activities such as jumping, running, and rapid directional changes — particularly relevant for athletes.
Responses are rated on a 5-point Likert scale (0 = unable to perform, 4 = no difficulty). Scores are summed and converted to percentages, with 100% representing full function.
Psychometric properties
Reliability
Test–retest: Hale and Hertel【1】 reported very high reliability, with ICC = 0.89 (1 week) and 0.93 (6 weeks) for FADI. For FADI Sport, ICC ranged from 0.84 to 0.92.
Interrater and intrarater: Strong correlations both between and within raters in patients with CAI.
Validity
Construct validity: FADI significantly distinguishes between affected and unaffected ankles (p < 0.001)【2】.
Content validity: Developed with input from both experts and patients, ensuring relevance to functional limitations.
Responsiveness
Effect size (ES): After 6 weeks of rehabilitation, Hale and Hertel【1】 reported ES = 0.52 for FADI and 0.71 for FADI Sport.
Clinical improvement: FADI increased from 87.1% (±12.1) to 94.4% (±6.1), while FADI Sport increased from 78.4% (±12.9) to 89.5% (±11.3).
Normative data
Studies have reported reference values:
Patients with CAI: FADI = 89.6% (±9.1), FADI Sport = 79.5% (±12.7)【1】.
Control groups: FADI = 99.9% (±0.3), FADI Sport = 99.8% (±0.7)【1】.
Conclusion
The Foot and Ankle Disability Index (FADI) is a reliable and validated tool for assessing functional limitations in the foot and ankle. With its strong psychometric properties and ability to capture changes over time, FADI is highly useful in both clinical and research settings. While it may be less suitable for older patients, it remains a valuable instrument for evaluating and monitoring athletes and patients with chronic ankle instability.
Sources:
Sheri A. Hale og Jay Hertel. Reliability and Sensitivity of the Foot and Ankle Disability Index in Subjects With Chronic Ankle Instability. Journal of Athletic Training 2005;40(1):35–40.
Eechaute et al. The clinimetric qualities of patient-assessed instruments for measuring chronic ankle instability: A systematic review. BMC Musculoskeletal Disorders 2007, 8:6 doi:10.1186/1471-2474-8-6.
Christopher R. Carcia et al. Validity of the Foot and Ankle Ability Measure in Athletes With Chronic Ankle Instability. Journal of Athletic Training 2008;43(2):179–183.
Robroy L. Martin. A survey of self-reported outcome instruments for the foot and ankle. J Orthop Sports Phys Ther 2007;37(2):72-84. doi:10.2519/jospt.2007.2403.
Gilani, S. F., & Amin, M. S. Operative treatment of displaced intra-articular fractures of Calcaneum: Is it worthwhile? S-162, 64(12), 161–166.
Pugia ML, Middel CJ, Seward SW. Comparison of acute swelling and function in subjects with lateral ankle injury. J Orthop Sports Phys Ther. 2001;31:384–388.
