Translation, reliability and validity of the Turkish versions of Norwich Patellar Instability score and The Banff Patellar Instability Instrument 2.0

Background Current treatment options for patellofemoral (PF) instability have required functional scoring systems. The Banff Patellar Instability Instrument (BPII) 2.0 and Norwich Patellar Instability (NPI) scores were explicitly created to meet the need to evaluate PF instability. Different patient-reported outcome measurements (PROMs) are used to evaluate anterior knee problems. Objectives To test the validity and reliability of the Turkish version of the BPII 2.0 and NPI score. Study design and methods Fifty-one patients that operated for PF instability, older than eighteen years old, were included in this study. Turkish translation of the BPII 2.0 and NPI scores was undertaken through translation into Turkish by an independent translator. Two tests were repeated seven days apart. Intraclass correlation coefficient (ICC) was used for test–retest reliability. Internal consistency was analyzed using Cronbach's alpha. Validity was assessed by correlating the Kujala and Lysholm knee scores. Results Fifty-one patients (34 females/17 males), the average age was 25 ± 7, were included in this study. Cronbach's alpha value was 0.829 for BPII 2.0 and 0.843 for NPI for the first time answered by patients. ICC values applied to evaluate test–retest reliability were 0.904 ( p < 0.05) for BPII 2.0 and 0.915 ( p < 0.05) for NPI. There was a moderate correlation between the BPII 2.0 Turkish version and the Kujala score. There was a very high correlation between the Turkish version of the BPII 2.0 and Lysholm knee scores. An excellent negative correlation was found between Norwich and Kujala scores ( r = −0.819, p < 0.05). The correlation coefficient between Norwich and Lysholm scores was −0.662, indicating a high negative correlation ( p < 0.05). The correlation coefficients between the Turkish version of BPII 2.0 and NPI were −0.533 ( p < 0.05). Conclusions The Turkish version of the BPII 2.0 and NPI score is a reliable and valid instrument for Turkish-speaking patients with patellofemoral instability.