ACL Injury and Reconstruction Increases Pain Sensitivity and Reduces Arterial Flow Mediated Dilation

A preliminary investigation of pressure pain sensitivity and the vascular effects of ACL injury with subsequent surgical reconstruction was carried out using a non-randomized, cross-sectional approach. One investigational visit was conducted on 15 subjects greater than six months status-post ACL reconstruction, while 14 subjects without lower extremity injury served as controls. All participants were between 18-40 years old and free of cardiovascular disease. Information on demographics, physical activity, medical history, and LE injury was collected for both groups. Pressure pain threshold with pressure algometry and arterial vascular dilation with ultrasonography (flow-mediated dilation) were assessed in both the upper and lower extremities. Hyperalgesia and impaired FMD was observed in the ACL group compared to the control. This is a novel finding in human research and as developed can improve the understanding of post-traumatic knee OA and a possible link to cardiovascular disease. Significant hyperalgesia was observed local and contralateral to the ACL reconstruction. A trending pattern of hyperalgesia was also observed at tibial measurement sites. FMD comparisons between groups reached statistical significance, while, interestingly the greatest impairment in FMD occurred in the popliteal artery contralateral to a unilateral ACL reconstruction. This contralateral arterial impairment likely represents an imbalance between local inflammatory factors and spinally mediated reflexes effecting smooth muscle control. Future research is recommended to expand on the current project with larger sample sizes, more extensive investigation of inflammatory cytokines, serum or urine analysis of type II cartilage byproducts and a more detailed analysis of arterial function.