Translation, cross-cultural adaptation, and validation of the Italian version of the anterior cruciate ligament–return to sport after injury (ACL-RSI) scale and its integration into the K-STARTS test

BACKGROUND: The timing of a return to sport (RTS) after anterior cruciate ligament reconstruction (ACLR) represents a major subject of debate in sports medicine practice. Recently, the Knee Santy Athletic Return to Sport (K-STARTS) composite test was validated. This consists of a battery of physical tests and a psychological evaluation using the anterior cruciate ligament–return to sport after injury scale (ACL-RSI). This study aimed to translate the ACL-RSI and K-STARTS from English to Italian and determine the scale’s reliability and validity in an Italian context. METHODS: The translation and cultural adaptation process was performed according to the guidelines for the cross-cultural adaptation of self-report measures. The patients were asked to fill an anonymized online form created for this purpose that included the KOOS, the Lysholm, the IKDC-SKF, and the Italian translation of the ACL-RSI (ACL-RSI-It). After 1 week, the attendees were asked to repeat the ACL-RSI-It to investigate the test–retest reliability. RESULTS: The final study population comprised 115 patients who underwent ACLR, with a mean follow-up of 37.37 ± 26.56 months. The ACL-RSI-It showed axcellent internal consistency (Cronbach’s α = 0.963), reliability (test–retest ICC = 0.966), and good construct validity (positive correlations with the other scales were above 75%). CONCLUSIONS: The ACL-RSI-It is valid, reliable, and comparable to the original English version of the questionnaire for Italian-speaking patients. It can be used to assess the psychological readiness of patients for a RTS after primary and unilateral ACLR, and can be integrated into the Italian K-STARTS test. LEVEL OF EVIDENCE: Level II. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s10195-021-00622-7.