Validity, Responsiveness, and Reliability of the ACL-QOL in an Adolescent Population

Background: The anterior cruciate ligament quality of life (ACL-QOL) score is a disease-specific patient-reported outcome measure that assesses patients with ACL deficient and reconstructed knees. The ACL-QOL has demonstrated validity, responsiveness, and reliability in adult populations but has yet to be specifically evaluated in adolescent patients. The purpose of this study was to assess the validity, responsiveness, and reliability of the ACL-QOL in an adolescent population.

Methods: Between 2010 and 2015, questionnaires from 294 consecutive adolescent patients consented for an ACL reconstruction were collected from an orthopaedic sport medicine clinic. The ACL-QOL was administered preoperatively, and at 6, 12, and 24 months following primary ACL reconstruction. To assess content validity, the Cronbach α and floor and ceiling effects were measured. Question reading level was measured with an online tool (https://readable.com/). Responsiveness was assessed with a 1-way analysis of variance to compare the preoperative and postoperative time periods. A test-retest strategy with completion of the ACL-QOL twice within 3 weeks was used to assess reliability using an intraclass correlation coefficient (ICC 2,k) and the SEM.

Results: The ACL-QOL demonstrated high content validity with a Cronbach αbetween 0.93 and 0.97, with no evidence of floor or ceiling effects at any study time point. The mean readability grade level was calculated to be 6.9, along with a readability score of 68. The ACL-QOL scores revealed a statistically significant improvement over time (P<0.001) with a Cohen d of 0.56, indicating a large effect size. Test-retest reliability revealed an ICC (2,k) of 0.997 (95% confidence interval=0.992-0.999).

Conclusions: The ACL-QOL demonstrated content validity, responsiveness to change, and reliability in an adolescent ACL reconstruction population. The readability of the ACL-QOL is acceptable for adolescents with an ACL injury. The ACL-QOL is a valid, responsive, and reliable patient-reported outcome measure that can be used in an adolescent population with ACL deficiency or following ACL reconstruction.

Level of evidence: Level III.