Establishing Threshold Values for the Patient Acceptable Symptom State After Anterior Cruciate Ligament Reconstruction for the Self Knee Value and the Anterior Cruciate Ligament-Return to Sport after Injury Scale.

Background: The Patient Acceptable Symptom State (PASS) has become a useful indicator, but to date, no threshold value has been defined for the Self Knee Value (SKV) and the Anterior Cruciate Ligament-Return to Sport after Injury (ALC-RSI) scale.

Purpose: To define the PASS thresholds for the SKV and ACL-RSI scale in patients 1 to 5 years after anterior cruciate ligament reconstruction (ACLR).

Study design: Case-control study; Level of evidence, 3.

Methods: The authors conducted a retrospective analysis based on data from a prospective cohort study of patients who underwent primary ACLR. Patients <50 years completed a survey at the end of follow-up, ranging from 1 to 5 years after reconstruction. The survey covered the SKV, the ACL-RSI scale, and a PASS question for each patient-reported outcome (PRO). The PASS was calculated using the area under the receiver operating characteristic (ROC) curve and absolute postoperative PROs.

Results: A total of 890 patients answered the questionnaire, at a mean follow-up of 39.2 ± 16.8 months after primary ACLR. Among them, 85.8% achieved an acceptable symptom state based on the SKV, and 76% based on the ACL-RSI scale. The ROC curve analysis allowed determination of PASS thresholds at 71% (sensitivity, 0.86; specificity, 0.80) for the SKV and 60% (sensitivity, 0.84; specificity, 0.74) for the ACL-RSI scale. Those who achieved the PASS were younger: SKV-PASS-Y = 28.0 ± 9.7 years vs. 30.1 ± 10.3 years (p = 0.03) for SKV-PASS-N and 27.9 ± 9.7 years for the ACL-RSI vs. 29.6 ± 10.1 years (p = 0.03) for ACL-RSI-PASS-N, and had a lower body mass index for both scores with a mean BMI of 24.0 ± 3.6 vs. 24.7 ± 3.7 (p = 0.04) and 23.9 ± 3.6 vs. 24.7 ± 3.8 (p = 0.007).

Conclusion: Although the PASS has been validated in several previous studies, this is the first study to determine PASS thresholds for the SKV and ACL-RSI scale with excellent sensitivity and excellent to acceptable specificity, at 1 to 5 years after primary ACLR. This should allow practitioners to extend the use of the PASS to PROs such as the SKV and the ACL-RSI scale, and thus facilitate the assessment of large cohorts of patients in future studies.