Anterior Cruciate Ligament Reconstruction Reinitiates an Inflammatory and Chondrodegenerative Process in the Knee Joint.

Anterior cruciate ligament(ACL) injury leads to a sustained increase in synovial fluid concentrations of inflammatory cytokines and biomarkers of cartilage breakdown. While this has been documented post-injury, it remains unclear whether ACL reconstruction surgery contributes to the inflammatory process and/or cartilage breakdown.This study is a secondary analysis of 14 patients (9 males/5 females, mean age=19, mean BMI=28) enrolled in an IRB-approved randomized clinical trial. Arthrocentesis was performed at initial presentation (mean=6 days post-injury), immediately prior to surgery (mean=23 days post-injury), one-week post-surgery, and one-month post-surgery. ELISA kits were used to determine concentrations of CTXII, IL-6 and IL-1β in the synovial fluid. The log transformed IL-1β was not normally distributed; therefore, changes between time points were evaluatedusing a non-parametric Kruskal-Wallis one-way ANOVA. IL-1β concentrations significantly increased from the day of surgery to the first postoperative time point (p .05).IL-6 concentrations at 1 week post-surgery were significantly higher than at initial presentation (p=0.013), the day of surgery (p .99) but significantly increased at 4 weeks post-surgery (p<.01). ACL reconstruction appears to reinitiate an inflammatory response followed byan increase in markers for cartilage degradation. ACL reconstruction appears to initiate a second "inflammatory hit" resulting in increased chondral breakdown suggesting that post-operative chondroprotection may be needed. This article is protected by copyright. All rights reserved.