The Swedish National Anterior Cruciate Ligament Register A Report on Baseline Variables and Outcomes of Surgery for Almost 18,000 Patients

Background: The Swedish National Anterior Cruciate Ligament Register provides an opportunity for quality surveillance and research. Purpose: The primary objective was to recognize factors associated with a poorer outcome at an early stage. Study Design: Case series; Level of evidence, 4. Methods: Registrations are made using a web-based protocol with 2 parts: a patient-based section with self-reported outcome scores and a surgeon-based section, where factors such as cause of injury, previous surgery, time between injury and reconstruction, graft selection, fixation technique, and concomitant injuries are reported. The self-reported outcome scores are registered preoperatively and at 1, 2, and 5 years. Results: Approximately 90% of all anterior cruciate ligament (ACL) reconstructions performed annually in Sweden are reported in the register. Registrations during the period 2005-2010 were included (n = 17,794). After excluding multiligament reconstructions and reoperations, the male: female ratio was 57.5: 42.5 for both primary (n = 15,387) and revision (n = 964) surgery. The cause of injury was soccer in approximately half the male patients and in one third of the female patients. All subscales of the Knee injury and Osteoarthritis Outcome Score (KOOS) were significantly improved 1, 2, and 5 years postoperatively in patients undergoing primary reconstructions. In terms of the KOOS, revisions did significantly less well than primary reconstructions on all follow-up occasions, and smokers fared significantly less well than nonsmokers both preoperatively and at 2 years. Patients who had concomitant meniscal or chondral injuries at reconstruction did significantly less well preoperatively and at 1 year in terms of most KOOS subscales compared with patients with no such injuries. At 5 years, a significant difference was only found in terms of the sport/recreation subscale. Double-bundle reconstructions revealed no significant differences in terms of all the KOOS subscales at 2 years compared with single-bundle reconstructions (114 double-bundle vs 5109 single-bundle). During a 5-year period, 9.1% (contralateral, 5.0%; revision, 4.1%) of the patients underwent a contralateral ACL reconstruction or revision reconstruction of the index knee. The corresponding figure for 15- to 18-year-old female soccer players was 22.0%. Conclusion: Primary ACL reconstruction significantly improves all the subscales of the KOOS. Young female soccer players run a major risk of reinjuring their ACL or injuring the contralateral ACL; revision ACL reconstructions do less well than primary reconstructions, and smokers do less well than nonsmokers.