Introduction Electrolysis Percutaneous Intratissue (EPI) is a new technique that involves the application of a galvanic current with an acupuncture needle that causes a theoretical local inflammatory process and subsequent tissue repair in the soft tissue. Electrolysis Percutaneous Intratissue (EPI) could promote wound healing. The purpose of this study was to examine the cellular response to Dry Needling versus Electrolysis Percutaneous Intratissue (EPI) after intratendinous treatment in an animal model.

Methods Design: Controlled laboratory study.

Setting. Department of Veterinary. University Complutense of Madrid-Spain.

Intervention. Twenty-four male Sprague Dawley adult rats were included in this experiment, weighing 190–240 g. In all cases, healthy Achilles tendons were treated. In the intervention group (n=18), one Achilles tendon was treated with dry needling, and the other was treated with electrolysis percutaneous intratissue. In the control animals (n=6) no intervention was carried out. Twenty four total tendons were treated with dry needling, and 24 tendons with electrolysis percutaneous intratissue, and 12 tendons were the control animals. In the experimental animals, one Achilles tendon was treated with dry needling (two impacts), and the other was treated with EPI 4 mA, 4 segs. and 2 impacts. Animals were euthanized after 0, 1, 3, 8, 14 and 21days after intervention by CO₂ asphyxiation. Muscle–Achilles tendon–bone units were harvested by transection of the middle part of the gastrocnemius muscle and of the calcaneus. Tendons were harvested and stained using E&H and scored semi-quantitatively for total white blood cells (WBCs), mononuclear cells (macrophages and lymphocytes), polymorphonuclear cells (PMNs), vascularity, fiber structure, and fibrosis.

Results After intervention the macroscopic findings (0 days) inflammatory response and haemorrhage were higher in EPI group versus dry needling. There is no significant difference in the cellularity regardless of the intervention types (dry needling vs EPI) at 0 days after intratendinous intervention. Compared with Dry Needling, Electrolysis Percutaneous Intratissue causes a significantly greater acute inflammatory response at 1 and 3 days after intervention and focal areas of scar tissue. Compared with findings in control specimens, histological analysis of EPI showed a marked inflammatory infiltrate. Histological examination of the repair tendon tissue showed that by 14 days delivery of EPI led to the formation of well-organised, tendinous tissue with large collagen fibres.

Discussion Electrolysis Percutaneous Intratissue can stimulate the tendon biology, initiate an inflammatory response and promote wound healing in normal tendon in rats.

Limitations of the study. A limitation of the present study is the use of rat Achilles tendon, which does not accurately reflect human Achilles tendon. Future investigations are necessary to apply these findings to the clinical setting.