Prosthetic mechanobiology : how prosthesis-related loading can influence skeletal muscle health

  • Marisa Sargent

Student thesis: Doctoral Thesis

Abstract

The soft tissue of the residual limb in transtibial prosthetic users encounters unique biomechanical challenges. Although not intended to tolerate high loads and deformation, it becomes a weight-bearing structure within the residuum-prosthesis complex. Consequently, skeletal muscles may be damaged, resulting in Deep Tissue Injury (DTI). While considerable effort has gone into DTI research on immobilised individuals and static loading conditions, only little is known about the effect of a dynamic loading environment as experienced by prosthetic users. The aim of this project was therefore to investigate the influence of prosthesis-related loading conditions on skeletal muscle tissue with the means of a newly developed ex vivo animal model. Soleus and extensor digitorum longus muscles of male Sprague Dawley rats were dissected and transversely compressed with a flat-ended indenter. The generated compressive stress was predicted through finite element modelling. Five different protocols were tested: (a) static loading for 1h or 2h representing standing and sitting, (b) dynamic loading with a frequency of 1.42Hz for 1h or 2h representing walking, and (c) dynamic loading with a frequency of 4Hz for 1h representing running. Subsequently, dead cells were identified through fluorescent staining with Procion Yellow MX4R and quantified in a semi-automated process. Extending the loading duration increased the amount of cellular damage significantly. Additionally, dynamic loading with a high frequency was more damaging than low frequency and static loading, suggesting the need to reconsider existing magnitude and duration-based cell death thresholds. While a direct translation of these results to the prosthetic user is difficult, they provide important insights into the adaptive capabilities of skeletal muscle. This can contribute to further research into the role of soft tissue deformation in residual limb pain and could inform future directions for prosthetic socket design and user guidelines.
Date of Award7 Jun 2023
Original languageEnglish
Awarding Institution
  • University Of Strathclyde
SponsorsUniversity of Strathclyde
SupervisorArjan Buis (Supervisor) & Sarah Day (Supervisor)

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