Background
In patients with anterior cruciate ligament reconstruction (ACLR), little is known about the threshold of patient-reported outcomes (PROs) at which patients perceive to have attained a substantial clinical benefit (SCB). No previous study has evaluated the SCB of ACLR in terms of daily activities in general population.
Hypothesis/Purpose: PROs commonly used in ACLR would have acceptable reliability in predicting SCB, and previously identified factors, such as demographic factors and isokinetic tests, would be able to predict reaching the SCB value of each PRO.
Study Design: Case Series; Level of Evidence: 4.
Methods
The Lysholm score, International Knee Documentation Committee Subjective Knee Evaluation Form (IKDC-SKF), Tegner activity scale, and the ACL–Return to Sport after Injury (ACL-RSI) scale were examined pre- and postoperatively in 76 patients who underwent ACLR. Patients responded to two independent anchor questions about daily discomfort and functional recovery at the 12-month follow-up visit. Receiver operating characteristic (ROC) curve was used to differentiate between patients who responded being “none” or “mild” difficulty with use of a question derived from the Knee injury and Osteoarthritis Outcome Score (KOOS) subscale and between those who answered with a score of = 8 or < 8 out of 10 with use of non-validated but more injury-specific functional question. For each SCB measure, two response parameters were used : raw score at postoperative one-year, net change. Multivariable regression analyses were performed to determine factors affecting the SCB.
Results
The raw postoperative scores corresponding to the SCB for the Lysholm, IKDC-SKF, Tegner, and ACL-RSI scale were 88.0, 85.1, 6.5, and 64.2 for the first anchor question and 84.5, 77.7, 5.5, and 57.1 for the second anchor question, respectively. The AUC values obtained from analysis of the raw postoperative PROs, unlike the net score changes, were all statistically significant (P < .05), with acceptable to excellent reliability. Younger age and greater muscle strength were predictive of SCB achievement in all PROs.
Conclusion
The postoperative Lysholm, IKDC-SKF, and ACL-RSI scale scores showed excellent reliability in predicting the SCB after ACLR in the general population. The age at surgery and thigh muscle strength influenced the SCB for each PRO.
Key Terms: anterior cruciate ligament reconstruction; general population; patient-reported outcome; significant clinical benefit