Investigating the birth-related caudal maternal pelvic floor muscle injury: The consequences of low cycle fatigue damage

• Type: Article in International Scientific Journal
• Date: 2020

Authors

Vila Pouca, MCPV (Author) Other; Parente, MPL (Author) FEUP; Renato Natal Jorge (Author) FEUP; Ashton Miller, JA (Author) Other

Journal

Title: Journal of the Mechanical Behavior of Biomedical Materials

Vol. 110

ISSN: 1751-6161

Publisher: Elsevier

Indexing

ISI Web of Knowledge - 0 Citations

Scopus - 0 Citations

Other information

Authenticus ID: P-00S-FTG

DOI: 10.1016/j.jmbbm.2020.103956

Abstract (EN): Background: One of the major causes of pelvic organ prolapse is pelvic muscle injury sustained during a vaginal delivery. The most common site of this injury is where the pubovisceral muscle takes origin from the pubic bone. We hypothesized that it is possible for low-cycle material fatigue to occur at the origin of the pubovisceral muscle under the large repetitive loads associated with pushing during the second stage of a difficult labor. Purpose: The main goal was to test if the origin of the pubovisceral muscle accumulates material damage under sub-maximal cyclic tensile loading and identify any microscopic evidence of such damage. Methods: Twenty origins of the ishiococcygeous muscle (homologous to the pubovisceral muscle in women) were dissected from female sheep pelvises. Four specimens were stretched to failure to characterize the failure properties of the specimens. Thirteen specimens were then subjected to relaxation and subsequent fatigue tests, while three specimens remained as untested controls. Histology was performed to check for microscopic damage accumulation. Results: The fatigue stress-time curves showed continuous stress softening, a sign of material damage accumulation. Histology confirmed the presence of accumulated microdamage in the form of kinked muscle fibers and muscle fiber disruption in the areas with higher deformation, namely in the muscle near the musculotendinous junction. Conclusions: The origin of ovine ishiococcygeous muscle can accumulate damage under sub-maximal repetitive loading. The damage appears in the muscle near the musculotendinous junction and was sufficient to negatively affect the macroscopic mechanical properties of the specimens.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 17