The effect of dry needling and treadmill running on inducing pathological changes in rat Achilles tendon

Abstract

Achilles tendinopathy is a common degenerative condition without a definitive treatment. An adequate chronic animal model of Achilles tendinopathy has not yet been developed. The purpose of this study was to evaluate the individual and combined effects of dry needling and treadmill running on the Achilles tendon of rats. Percutaneous dry needling, designed to physically replicate microrupture of collagen fibers in overloaded tendons, was performed on the right Achilles tendon of 80 Sprague–Dawley rats. The rats were randomly divided into two groups: a treadmill group, which included rats that underwent daily uphill treadmill running (n = 40), and a cage group, which included rats that could move freely within their cages (n = 40). At the end of weeks 1 and 4, 20 rats from each group were sacrificed, and bilateral Achilles tendons were collected. The harvested tendons were subjected to mechanical testing and histological analysis. Dry needling induced histological and mechanical changes in the Achilles tendons at week 1, and the changes persisted at week 4. The needled Achilles tendons of the treadmill group tended to show more severe histological and mechanical changes than those of the cage group, although these differences were not statistically significant. Dry needling combined with free cage activity or treadmill running produced tendinopathy-like changes in rat Achilles tendons up to 4 weeks after injury. Dry needling is an easy procedure with a short induction period and a high success rate, suggesting it may have relevance in the design of an Achilles tendinopathy model.

• Achilles
• animal model
• needling
• overuse
• tendinopathy

Acknowledgments

The authors thank Young Jick Kim, PhD (Cell Therapy Center, Ajou University School of Medicine, Suwon, Korea), for directing the mechanical testing and data processing.

Declaration of interest

The authors report no conflicts of interest with regards to this paper. The authors alone are responsible for the content and writing of the paper.

This work was supported by the National Research Foundation of Korea (NRF) funded by the Korea government (MEST) (Grant no. 2012R1A1A1038954) and an Inha Research Grant (44758-01).