Comparison of community-based ACL reconstruction registries in the U.S. and Norway.

INTRODUCTION Joint registries have demonstrated value as a resource for the study of large numbers of patients, providing the opportunity to study rare occurrences and identify early failures of surgical procedures. Anterior cruciate ligament (ACL) reconstruction registries have been established in Norway and the U.S. In this study, we compared the preoperative characteristics of the Norwegian National Knee Ligament Registry (NKLR) and the Kaiser Permanente Anterior Cruciate Ligament Reconstruction Registry (KP ACLRR) cohorts. METHODS A cross-sectional comparison of the NKLR and KP ACLRR cohorts registered between 2005 and 2010 was performed. Aggregate level data including preoperative patient characteristics, mechanisms of injury, preoperative Knee Injury and Osteoarthritis Outcome Score (KOOS), intraoperative findings, and adjusted revision rates were shared between the two registries, and a descriptive analysis was conducted. RESULTS During the study period, 10,468 primary ACL reconstructions were entered in the NKLR and 10,394, in the KP ACLRR. The age at the time of surgery was similar between the two cohorts (twenty-seven years in the NKLR versus twenty-eight years in the KP ACLRR), although the KP ACLRR had a higher proportion of males (65% versus 58%, p < 0.001). The revision rate per follow-up year was 0.9% in the NKLR and 1.5% in the KP ACLRR. Soccer was the most common mechanism of injury in both registries (40.0% in the NKLR and 26.6% in the KP ACLRR). The preoperative KOOS was statistically different, but the difference was not clinically relevant (defined as a change of >10 points). A higher prevalence of meniscal tears was seen in the KP ACLRR (61% versus 49%, p < 0.001). CONCLUSIONS Baseline findings are so congruent between the NKLR and the KP ACLRR cohorts that comparisons between these two registries will likely provide information to the orthopaedic community that can be generalized.