Effect of extracorporeal shock wave therapy on cultured tenocytes

Background: Little has been reported about the biologic effect of shock waves on human normal or pathologic tendon tissue. We hypothesized that inflammatory cytokine and MMP production would be down-regulated by shock wave stimulation. Materials and Methods: Diseased Achilles tendon tissue and healthy flexor hallucis longus tissue were used. Shock wave treatment was applied to cultured cells at 0.17 mJ/inin ²energy 250, 500, 1000, and 2000 times. Results: A dose-dependent decrease in cell viability was noted in cells receiving 1000 and 2000 shocks (86.0 ± 5.6%, p = 0.01 and 72.4 ± 8.9%, p = 0.001) as compared with the normal control. Cell count in the 500-shock group increased by 23.4% as compared with the control (p = 0.05). The concentration of MMP 1, 2, and 13 was higher in diseased tenocytes as compared with normal cells (p =0.04, all comparisons). IL-6 levels were higher in the diseased tenocytes as compared with normal tenocytes (44.10 ± 16.72 versus 0.21 ± 0.55 ng/ml, (p < 0.05). IL-1 levels in normal cells increased (2.24 ± 5.02 ng/ml to 9.31 ± 6.85 ng/ml) after shock wave treatment (p = 0. 04). In diseased tenocytes, levels of MMP-1 (1.12 ± 0.23 to 0.75 ± 0.24 ng/ml; p = 0.04) and MMP-13 (1.43 ± 0.11 to 0.80 ± 0.15 ng/ml; p = 0.04) were significantly decreased after shock wave treatment. The IL-6 level in diseased tenocytes was decreased (44.10 ± 16.72 to 14.66 ± 9.49 ng/ml) after shock wave treatment (p = 0.04). Conclusion: Higher levels of MMPs and ILs were found in human tendinopathy-affected tenocytes as compared with normal cells. ESWT decreased the expression of several MMPs and ILs. Clinical Relevance: This mechanism may play an important role in shock wave treatment of tendinopathy clinically.