Cytokine Profiling in Acute Anterior Cruciate Ligament Injury

Purpose: To evaluate the presence and relative concentrations of cytokines, known to be involved in the inflammatory cascade, in acute anterior cruciate ligament (ACL) injury. Methods: We evaluated an extensive cytokine profile in synovial fluid from 12 patients with acute ACL injury undergoing arthroscopy compared with 15 control subjects using a BioPlex assay (Bio-Rad Laboratories, Hercules, CA) to measure the concentration of 17 inflammatory cytokines. Results: In patients with acute ACL injury compared with asymptomatic control subjects, the following cytokines were identified at significantly increased concentrations (P < .001, Mann-Whitney U test) compared with control samples: interleukin 6 (105 +/- 72 v 0 +/- 0 pg/ml), interferon gamma (1,544 +/- 608 v 9 +/- 7.5 pg/ml), macrophage inflammatory protein 1 beta (16 +/- 3.8 v 0.3 +/- 0.2 pg/ml), and monocyte chemotactic protein 1 (35 +/- 13 v 0.5 +/- 0.4 pg/ml). There was no case of a cytokine exhibiting increased levels in asymptomatic compared with symptomatic knee samples. Conclusions: This investigation identified 4 specific cytokines (interleukin 6, interferon gamma, monocyte chemotactic protein 1, and macrophage inflammatory protein 1 beta) out of a panel of 17 inflammatory molecules for which the levels were consistently elevated in the context of ACL injury compared with non-painful, non-acutely injured knees in a volunteer population. Level of Evidence: Level IV, prognostic case series.