Abstract
BACKGROUND: The Banff Patellar Instability Instrument 2.0 (BPII 2.0) and Norwich Patellar Instability (NPI) score are reliable, valid patient-reported outcome (PRO) measures for evaluating patellofemoral instability. Both have been translated and culturally adapted to various languages to document PROs accurately. However, no validated Arabic versions of these PRO measures exist. PURPOSE: To translate the BPII 2.0 and NPI score into Arabic and assess the reliability and validity of the translated questionnaires. STUDY DESIGN: Cohort study (diagnosis); Level of evidence, 3. METHODS: The NPI score and BPII 2.0 were translated into Arabic based on standard guidelines recommended by the Consensus-based Standards for the selection of health Measurement Instruments. Patients who underwent patellofemoral stabilization surgery were included in this study. Respondents completed the translated versions of the questionnaires 1 week apart. The validity of the translation was assessed using Cronbach alpha, and Pearson correlation coefficient (r) was used to determine the relationship between the Arabic versions of the NPI score, BPII 2.0, and Kujala Score (KS). Test-retest reliability was assessed using the intraclass correlation coefficient. RESULTS: The translated versions were assessed in 83 patients and found reliable. The response rate was 94.3%. A negative correlation was found between the KS and NPI score (r = -0.80; P < .05) and a positive correlation with BPII (r = 0.84; P < .05). A significant negative correlation was noted between the NPI and the BPII (r = -0.71). For first-time responses, Cronbach alpha for the NPI score was 0.80, with an intraclass correlation coefficient of 0.80 (0.68-0.83), while the BPII was 0.91 (0.87-0.93) and the KS was 0.80 (0.73-0.86). No floor or ceiling effects were observed. CONCLUSION: The study demonstrated that the translated Arabic versions of the BPII and NPI score are valid and reliable for measuring PROs in Arabic-speaking patients with patellofemoral instability.