Inflammatory cytokines and matrix metalloproteinases in the synovial fluid after intra-articular elbow fracture.

BACKGROUND AND HYPOTHESIS: Post-traumatic elbow contracture remains a common and challenging complication with often unsatisfactory outcomes. Although the etiology is unknown, elevated or abnormal post-fracture synovial fluid cytokine levels may result in the migration of fibroblasts to the capsule and contribute to capsular pathology. Thus, the purpose of this study was to characterize the cytokine composition in the synovial fluid fracture hematoma of patients with intra-articular elbow fractures.

METHODS

The elbow synovial fluid fracture hematoma of 11 patients with intra-articular elbow fractures was analyzed for CTXII (C-terminal telopeptides of type II collagen [a cartilage breakdown product]) as well as 15 cytokines and matrix metalloproteinases (MMPs) including interferon γ, interleukin (IL) 1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, tumor necrosis factor α, MMP-1, MMP-2, MMP-3, MMP-9, and MMP-10. The uninjured, contralateral elbow served as a matched control. Mean concentrations of each factor were compared between the fluid from fractured elbows and the fluid from control elbows.

RESULTS

The levels of 14 of 15 measured cytokines and MMPs-interferon γ, IL-1β, IL-2, IL-4, IL-6, IL-8, IL-10, IL-12p70, IL-13, tumor necrosis factor α, MMP-1, MMP-3, MMP-9, and MMP-10-were significantly higher in the fractured elbows. In addition, post hoc power analysis revealed that 10 of 14 significant differences were detected with greater than 90% power. The mean concentration of CTXII was not significantly different between groups.

CONCLUSIONS

These results demonstrate a proinflammatory environment after fracture that may be the catalyst to the development of post-traumatic elbow joint contracture. The cytokines with elevated levels were similar, although not identical, to the cytokines with elevated levels in studies of other weight-bearing joints, indicating the elbow responds uniquely to trauma.