Validation of the Bulgarian version of Oxford foot and ankle questionnaire for children with flat foot deformity
DOI:
https://doi.org/10.2478/AMB-2025-0069Keywords:
validation, flexible flatfoot, pediatric, OxAFQ-CAbstract
Background: Pediatric fl exible fl atfoot, defi ned by a diminished or absent medial longitudinal arch, is a common anatomical variant with potential biomechanical consequences. While many cases are asymptomatic, symptomatic fl atfoot can impair gait mechanics and postural stability, leading to long-term functional limitations. Health-related quality of life (HRQoL) in children with fl atfoot remains underexplored, necessitating validated, patient-reported outcome measures (PROMs). The Oxford Ankle Foot Questionnaire for Children (OxAFQ-C) is the only validated PROM designed for pediatric foot and ankle disorders, yet its psychometric properties have not been evaluated in Bulgarian-speaking populations. Objective: This study aimed to adapt and validate the Bulgarian version of the OxAFQ-C, assessing its reliability, internal consistency, construct validity, and feasibility in pediatric patients diagnosed with fl exible fl atfoot. Methods: The translation and cultural adaptation followed international guidelines, including forward-backward translations, expert panel reviews, and pre-testing with children and guardians. The final Bulgarian OxAFQ-C was administered to 995 children (aged 6-16) across three Bulgarian regions. Psychometric analyses included internal consistency (Cronbach’s alpha, α), test-retest reliability (Intraclass Correlation Coefficient, ICC), and construct validity through correlation with the Visual-Analogue-Scale Foot and Ankle (VAS FA). Exploratory Factor Analysis (EFA) assessed structural validity. Results: The Bulgarian OxAFQ-C demonstrated excellent internal consistency (Cronbach’s α > 0.90). Parent-child agreement was highest in the Physical Function domain (ICC ≥ 0.75) and moderate for other domains. Construct validity was confirmed, with moderate correlations between the Physical Function domain and VAS FA scores (r ≈ -0.43). EFA confirmed the three-factor structure. Conclusion: The Bulgarian adaptation of the OxAFQ-C is a reliable and valid instrument for assessing HRQoL in children with flexible fl atfoot. Its strong psychometric properties support its clinical and research utility in orthopedic and epidemiological studies.
References
Helfet AJ. Disorders of the foot. Philadelphia: Lippincott Williams & Wilkins; 1980.
Eiser C. Can parents rate their child’s health-related quality of life? Results of a systematic review Qual Life Res. 2001, 10: 347–357
Bjornson KF, McLaughlin JF. The measurement of health-related quality of life (HRQL) in children with cerebral palsy. Eur J Neurol. 2001, 8:183–193.
Meuleners LB, Lee AH, Binns CW, et al. Quality of life for adolescents: assessing measurement properties using structural equation modelling. Qual Life Res. 2003, 12(3):283-290.
Eiser C, Morse R. Quality-of-life measures in chronic diseases of childhood. Health Technol Assess. 2001, 5(4):1-157.
Sherman MS, Slick DJ, Connolly MB, et al. Validity of three measures of health-related quality of life in children with intractable epilepsy. Epilepsia. 2002, 43:1230–1238.
Otley A, Smith C, Nicholas D, et al. The IMPACT questionnaire: a valid measure of health-related quality of life in pediatric inflammatory bowel disease. J Pediatr Gastroenterol Nutr. 2002, 35:557–563.
Morris C, Doll HA, Wainwright A, et al. The Oxford ankle foot questionnaire for children: scaling, reliability and validity. J Bone Joint Surg Br. 2008, 90(11):1451-1456.
Morris C, Doll H, Davies N, et al. The Oxford Ankle Foot Questionnaire for children: responsiveness and longitudinal validity. Qual Life Res. 2009, 18:1367–1376.
Hemmingsson H, Olafsdottir LB, Egilson ST. Agreements and disagreements between children and their parents in health-related assessments. Disabil Rehabil. 2017, 39:1059–1072.
Sousa VD, Rojjanasrirat W. Translation, adaptation and validation of instruments or scales for use in cross-cultural health care research: a clear and user-friendly guideline. J Eval Clin Pract. 2011, 17(2):268-274.
Richter M, Zech S, Geerling J, et al. A new foot and ankle outcome score: Questionnaire-based, subjective, visual analog-scale, validated, and computerized. Foot Ankle Surg. 2006, 12(4):191-199.
Cronbach LJ, Warrington WG. Time-limit tests: estimating their reliability and degree of speeding. Psychometrika. 1951, 16(3):167–188.
Lee KM, Lee J, Chung CY, et al. Pitfalls and important issues in testing reliability using intraclass correlation coefficients in orthopaedic research. Clin Orthop Surg. 2012, 4:149–155.
Polit DF, Beck CT. Nursing Research: Generating and Assessing Evidence in Nursing Practice. 10th ed. Philadelphia, PA, USA: Lippincott Williams & Wilkins, 2016.
Bland JM, Altman DG. Statistical methods for assessing agreement between two methods of clinical measurement. Lancet. 1986, 1(8476):307–310.
Sousa VD, Rojjanasrirat W. Translation, adaptation and validation of instruments or scales for use in cross-cultural health care research: a clear and user-friendly guideline. J Eval Clin Pract. 2011, 17(2):268-274.
Prinsen CAC, Mokkink LB, Bouter LM, et al. COSMIN guideline for systematic reviews of patient-reported outcome measures. Qual Life Res. 2018, 27(5):1147–1157.
Hajebrahimi F, Tarakci D, Arman N, et al. Cross-cultural adaptation, validity, and reliability of the Turkish version of the Oxford Ankle Foot Questionnaire for children with congenital talipes equinovarus. Foot Ankle Surg. 2021, 27(4):439-442.
Martinelli N, Romeo G, Bonifacini C. Validation of the Italian version of the Oxford Ankle Foot Questionnaire for children. Qual Life Res. 2016, 25:117–123.
Cho SH, Chung CY, Park MS, et al. Transcultural adaptation and validation of a Korean version of the Oxford Ankle Foot Questionnaire for children. Health Qual Life Outcomes. 2020,18 (1):118.
Burger E, Selles R, van Nieuwkasteele S, et al. The Dutch version of the Oxford Ankle and Foot Questionnaire for Children: Useful for evaluation of pediatric foot problems in groups. Foot Ankle Surg. 2019, 25(2):204-210.
Martinkevich P, Møller-Madsen B, Gottliebsen M, et al. Validation of the translated Oxford ankle foot questionnaire in 82 Danish children aged between five and 16 years. Bone Joint J. 2015, 97-B(3):420-426.
Kocher MS, Smith JT, Iversen MD, et al. Reliability, validity, and responsiveness of a modified International Knee Documentation Committee Subjective Knee Form (Pedi-IKDC) in children with knee disorders. Am J Sports Med. 2011, 39:933–939.
Karabinov V, Slavchev SA, Georgiev GP. Translation and Validation of the Bulgarian Version of the Boston Carpal Tunnel Questionnaire. Cureus. 2020, 12(10):e10901.
Tsenkov T, Slavchev S, Dimitrov N. Linguistic validation, adaptation, and reliability of the Liverpool Elbow Score’s patient-answered questionnaire in Bulgarian. Acta Medica Bulgarica. 2023, 50:33–36.
Nguyen MQ, Iversen MM, Harboe K, et al. Validity and reliability of the Manchester Oxford Foot Questionnaire (MOXFQ) in one-year postoperative ankle fracture patients – a validation study. J Patient Rep Outcomes. 2025, 9(1):14:14.
Downloads
Published
Issue
Section
License
Copyright (c) 2025 N. Gecheva, Z. Bozinovski, A. Gerchev, B. Hristov, V. Alexiev (Author)
This work is licensed under a Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License.
You are free to share, copy and redistribute the material in any medium or format under these terms.
Journal Acta Medica Bulgarica 
