Analysis of the Histological Effect of the Shock Waves on the Integrated Musculature of the Quadriceps of Wistar Rats

Objective: Shock waves are high-energy, high-pressure mechanical sound pulses used in medicine since 1980 with lithotripsy in urolithiasis. In addition, studies have demonstrated the osteogenic effect of shock waves indicating their use in skeletal diseases. Although several articles describe the benefits of shock waves in muscle diseases, assessments of its histological effect on the process of cell regeneration are lacking. Therefore, the objetive of this study is evaluate the histological effect of extracorporeal shock wave therapy on the intact musculature of Wistar rats. Materials and Methods: Twelve Wistar rats, with a mean age of 8 weeks, were studied for a period of 21 days. The quadriceps muscle of the right paws was submitted to 3 sessions of extracorporeal shock wave therapy at weekly intervals. The left legs were used as a control. Subsequently, the animals were euthanized and the quadriceps muscles were biopsied for histological study using histological slides stained in hematoxylin-eosin and Gomori's trichomium. Muscle fiber size, morphology and number of nuclei, existence of inflammatory infiltration, satellite cell count, and number of vessels were evaluated. Statistical calculations were performed using software R version 3.5.2 using non-parametric methods. Continuous variables relating to the legs of the same animal were compared using the Wilcoxon paired test (signed-rank). Discrete variables were compared using Fisher's exact test with mid-p correction. Results were considered statistically significant when p <0.05. Result: In the musculature of the right paws, there was an increase in fibrovascular and satellite cells proliferation with a statistically significant difference (p <0.005). Conclusion: The demonstration of the angiogenic power and the proliferation of satellite cells induced by extracorporeal shock waves, it is possible to affirm that this constitutes promising therapy for several muscle injuries. The acceleration of muscle recovery in athletes stands out as a example, by minimizing the impact on the competitor's performance, reducing muscle pain and spasticity, and improving muscle strength in tendinopathies.