Background Both physical and psychological readiness are important for a successful return to sport (RTS) and secondary prevention. The ACL-Return to Sport after Injury (ACL-RSI) and Injury-Psychological Readiness to Return to Sport (I-PRRS) scales were developed to assess psychological factors associated with RTS. Validity and reliability have been determined but responsiveness of both scales has not been examined yet.

Objective To investigate the responsiveness of the Dutch ACL-RSI and I-PRRS scales.

Design Prospective, cohort study.

Setting Patients from a university and regional hospital.

Patients Seventy athletes with ACL reconstruction 3–9 month previous to the start of the study completed both scales twice two months apart, plus a Global Rating of Change (GRC) questionnaire.

Main Outcome Measurements Distribution and logistic regression-based methods were used to study responsiveness.

Results The Standardized Response Mean (SRM) for the ACL-RSI was 0.3 and for the I-PRRS 0.1. The minimally important change (MIC) for ACL-RSI was 2.6 and for the I-PRRS 0.9. Since the smallest detectable change (SDC) was larger than MIC in individual patients, it does not seem possible to distinguish minimally important changes from measurement error in individual patients with either scale. At group level responsiveness of both scales seemed sufficient.

Conclusions In individual patients the responsiveness of the ACL-RSI and I-PRRS scales seems to be insufficient to detect changes in confidence over time with regard to return to sport after ACLR. Neither scale is able to distinguish minimally important changes from measurement error in individual patients. The scales are therefore less suitable for monitoring the effectiveness of individual interventions and to judge whether a patient has reached a change of importance. At the group level responsiveness seems sufficient, so the two scales can be used to investigate the effectiveness of an intervention at the group level.