Polymethylmethacrylate injections for augmentation and strengthening of abdominal muscles: an experimental model

Abstract

Introduction: Polymethylmethacrylate (PMMA) is a synthetic, inert, biocompatible and nontoxic polymer, the applications in the medical field are numerous, and indications are increasingly broad. Objectives: To evaluate whether the fibrous response to injection of PMMA microspheres into striated muscles confers increased volume and resistance to muscle stretch. Methods: A total of 20 Wistar rats were injected with, 30% PMMA gel into the right rectus abdominis muscle, while the left rectus muscle received SHAM injections. After 4 weeks, all abdominal rectus muscles were measured and stretched on a bench dynamometer until rupture. The samples were analyzed histologically to verify the tissue response to PMMA. Results: The right rectus abdominis muscles of rats that received PMMA gel injection had increased volume and the breaking strength was greater than 100% compared to the left rectus muscles that received SHAM injections. There was a significant deposition of type I and III collagen fibers around the PMMA injection sites. Conclusion: PMMA microspheres implanted into the rectus abdominis muscle of Wistar rats promote neocollagenesis and significantly increase the breaking strength when subjected to stretch test. The mild and desired foreign body type tissue reaction around the PMMA is not objection to the augmentation of the rectus abdominis muscle.