No differences in subjective knee function between surgical techniques of anterior cruciate ligament reconstruction at 2-year follow-up: a cohort study from the Swedish National Knee Ligament Register

PURPOSE: The purpose of this study was to investigate how different techniques of single-bundle anterior cruciate ligament (ACL) reconstruction affect subjective knee function via the Knee injury and Osteoarthritis Outcome Score (KOOS) evaluation 2 years after surgery. It was hypothesized that the surgical techniques of single-bundle ACL reconstruction would result in equivalent results with respect to subjective knee function 2 years after surgery. METHODS: This cohort study was based on data from the Swedish National Knee Ligament Register during the 10-year period of 1 January 2005 through 31 December 2014. Patients who underwent primary single-bundle ACL reconstruction with hamstrings tendon autograft were included. Details on surgical technique were collected using a web-based questionnaire comprised of essential AARSC items, including utilization of accessory medial portal drilling, anatomic tunnel placement, and visualization of insertion sites and landmarks. A repeated measures ANOVA and an additional linear mixed model analysis were used to investigate the effect of surgical technique on the KOOS(4) from the pre-operative period to 2-year follow-up. RESULTS: A total of 13,636 patients who had undergone single-bundle ACL reconstruction comprised the study group for this analysis. A repeated measures ANOVA determined that mean subjective knee function differed between the pre-operative time period and at 2-year follow-up (p < 0.001). No differences were found with respect to the interaction between KOOS(4) and surgical technique or gender. Additionally, the linear mixed model adjusted for age at reconstruction, gender, and concomitant injuries showed no difference between surgical techniques in KOOS(4) improvement from baseline to 2-year follow-up. However, KOOS(4) improved significantly in patients for all surgical techniques of single-bundle ACL reconstruction (p < 0.001); the largest improvement was seen between the pre-operative time period and at 1-year follow-up. CONCLUSION: Surgical techniques of primary single-bundle ACL reconstruction did not demonstrate differences in the improvement in baseline subjective knee function as measured with the KOOS(4) during the first 2 years after surgery. However, subjective knee function improved from pre-operative baseline to 2-year follow-up independently of surgical technique. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00167-017-4521-y) contains supplementary material, which is available to authorized users.