How Applicable Is Published Minimum Clinically Important Difference Literature to a Single-Center Anterior Cruciate Ligament Reconstruction Population?

Objectives: Patient-reported outcome measures (PROMs) are increasingly used to assess treatment success following anterior cruciate ligament reconstruction (ACLR). The purpose of this study was to determine rates of minimum clinically important difference (MCID) achievement for the Knee Injury and Osteoarthritis Outcome Score (KOOS) and Single Assessment Numeric Evaluation (SANE) following ACLR, evaluate overlap in MCID achievement between measures, and identify factors associated with failure to achieve MCID. Material and Methods: A prospectively collected PROM database from a single ambulatory surgical center was queried for ACLR procedures performed from 2009 to 2016. Revision procedures and patients undergoing concomitant ligament repairs/reconstructions were excluded. KOOS and SANE scores were assessed at two years. Patients were categorized according to achievement of literature-reported MCID thresholds for KOOS and/or SANE. Results: In total, 322 patients were included. At two years, 73.6% ( n =237) achieved MCID for KOOS, while 45.7% ( n =147) achieved MCID for SANE. Among patients achieving SANE MCID, 89.8% also achieved KOOS MCID, whereas only 55.7% of patients achieving KOOS MCID also achieved SANE MCID. Overall, 41.0% of patients achieved MCID for both measures, while 21.7% failed to achieve MCID for either. Compared with patients achieving MCID in at least one PROM, those who failed to achieve any MCID were more likely to have undergone ACLR for a chronic injury (11.4% vs 5.6%; p =0.04). Conclusion: MCID achievement rates differed substantially between KOOS and SANE following ACLR. Patients with chronic ACL injuries were less likely to achieve clinically meaningful improvement, suggesting timing from injury may influence postoperative outcomes.