Patient Predictors of Contralateral Anterior Cruciate Ligament Reconstruction - A Cohort Study on 9061 patients from The Swedish National Knee Ligament Register, with 5-year Follow-up

Abstract

Master thesis, Programme in Medicine, TITLE: Patient Predictors of Contralateral Anterior Cruciate Ligament Reconstruction A Cohort Study on 9061 patients from The Swedish National Knee Ligament Register, with 5-Year Follow-­‐up. AUTHOR: Sofia Gillén. ABSTRACT Background An injury to the contralateral anterior cruciate ligament (ACL) and a subsequent reconstructive surgery is one of the most serious complications after ipsilateral index ACL reconstruction. It may be career ending for an athlete. To be able to prevent a future injury it is important to identify predictors associated with contralateral ACL reconstruction. Purpose To investigate if seven patient variables were predictors of contralateral surgery after ACL reconstruction. Study Design Prospective cohort study; level of evidence, 2 Methods This register study is based on data from the Swedish National Knee Ligament Register. Patients who underwent index ACL reconstruction during the period of January 1, 2005 through December 31, 2008 were included. The inclusion criteria were age between 13 and 59 years with hamstring tendon or patellar tendon autografts in their primary reconstruction. Follow-­‐up started on date of index ACL reconstruction. Patients were followed; for five years, until the end of 2013 or until contralateral ACL reconstruction, whichever event occurred first. Following variables were investigated: patient sex, age at index reconstruction, activity at index injury, timing of surgery, graft selection, graft harvest site, meniscal and chondral injury. Relative risks (RRs) and 95% confidence intervals were calculated and adjusted for confounders using multivariate statistics. Results: A total of 9061 participants were included in the cohort. During the 5-­‐year follow-­‐up period of this study, a total of 270 contralateral ACL reconstructions were performed. The contralateral reconstruction rate was 3% (95% CI, 2.7-­‐3.4). Regression analysis revealed two significant associations. There was a significant higher risk of a contralateral ACL reconstruction for Young patient (males, RR=2.4 [95% CI, 1.7-­‐3.4] and females, RR=2.9 [95% CI, 1.9-­‐4.5], p<0.001) and for females with contralateral graft harvest (RR=3.3 [95% CI, 1.4-­‐ 7.8], p=0.006). Conclusion The most important findings were that age less than 20 years at the time of index ACL reconstruction predicted an almost 3 times higher risk of contralateral ACL reconstruction. Graft harvest from the contralateral knee at index ACL reconstruction predicted a more than 3 times higher risk for contralateral ACL reconstruction among female participants. There were no association between patient sex, activity at index injury, graft selection, meniscal and chondral injury and subsequent contralateral ACL reconstruction.