Cross-cultural adaptation and validation of the Italian versions of the Kujala, Larsen, Lysholm and Fulkerson scores in patients with patellofemoral disorders

BACKGROUND: The Kujala, Fulkerson, Larsen and Lysholm questionnaires have been demonstrated to be reliable and sensitive in assessing patients with patellofemoral pathology. The purpose of this study is to translate and cross-culturally adapt into Italian the English versions of the Kujala, Fulkerson, Larsen and Lysholm questionnaires, and undertake reliability and validity evaluations of the Italian versions of these scores in patients with patellofemoral pathology. MATERIALS AND METHODS: The cross-cultural adaptation process was carried out following the simplified Guillemin criteria. The questionnaires were administered to 63 patients with either patellar instability or painful patella syndrome. To assess the validity of the questionnaires, they were compared with the Oxford knee score. The questionnaires were administered to a subsample of 33 patients 5 days later to assess test–retest reliability. RESULTS: The interclass coefficient correlation was 0.96 for the Kujala score, 0.92 for the Larsen score, 0.96 for the Lysholm score, 0.94 for the Fulkerson score (P < 0.01), and 0.83 for the Oxford score. Pearson’s correlation was0.96 between the Kujala and Oxford scores, 0.90 between the Larsen and Oxford scores, 0.94 between the Lysholm and Oxford score, and 0.93 between the Fulkerson and Oxford scores. Responsiveness, calculated by standardized response mean, was 1.2, and effect size was 1.4. CONCLUSIONS: The Italian versions of the Kujala, Larsen, Lysholm and Fulkerson scoring systems were shown to be equivalent to their English versions and demonstrated good validity, reliability and responsiveness to surgical treatment of patellofemoral pathology. To the best of the authors’ knowledge, this is the first attempt to adapt four of the most common patellofemoral-specific scoring scales to the Italian language. LEVEL OF EVIDENCE: Level II. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1186/s10195-018-0508-9) contains supplementary material, which is available to authorized users.