A musculoskeletal model of the equine forelimb for determining surface stresses and strains in the humerus-part II. Experimental testing and model validation.
Abstract: The first objective of this study was to experimentally determine surface bone strain magnitudes and directions at the donor site for bone grafts, the site predisposed to stress fracture, the medial and cranial aspects of the transverse cross section corresponding to the stress fracture site, and the middle of the diaphysis of the humerus of a simplified in vitro laboratory preparation. The second objective was to determine whether computing strains solely in the direction of the longitudinal axis of the humerus in the mathematical model was inherently limited by comparing the strains measured along the longitudinal axis of the bone to the principal strain magnitudes and directions. The final objective was to determine whether the mathematical model formulated in Part I [Pollock et al., 2008, ASME J. Biomech. Eng., 130, p. 041006] is valid for determining the bone surface strains at the various locations on the humerus where experimentally measured longitudinal strains are comparable to principal strains. Triple rosette strain gauges were applied at four locations circumferentially on each of two cross sections of interest using a simplified in vitro laboratory preparation. The muscles included the biceps brachii muscle in addition to loaded shoulder muscles that were predicted active by the mathematical model. Strains from the middle grid of each rosette, aligned along the longitudinal axis of the humerus, were compared with calculated principal strain magnitudes and directions. The results indicated that calculating strains solely in the direction of the longitudinal axis is appropriate at six of eight locations. At the cranial and medial aspects of the middle of the diaphysis, the average minimum principal strain was not comparable to the average experimental longitudinal strain. Further analysis at the remaining six locations indicated that the mathematical model formulated in Part I predicts strains within +/-2 standard deviations of experimental strains at four of these locations and predicts negligible strains at the remaining two locations, which is consistent with experimental strains. Experimentally determined longitudinal strains at the middle of the diaphysis of the humerus indicate that tensile strains occur at the cranial aspect and compressive strains occur at the caudal aspect while the horse is standing, which is useful for fracture fixation.
Publication Date: 2008-07-08 PubMed ID: 18601449DOI: 10.1115/1.2898729Google Scholar: Lookup
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- Evaluation Study
- Journal Article
- Research Support
- Non-U.S. Gov't
- Validation Study
Summary
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The study focused on developing and validating a mathematical model to calculate strains of the horse’s humerus bone in different locations. The study also compared the results of the model with experimentally measured strains, primarily to help understand and predict incidents of stress fractures during bone graft processes.
Objective and Approach
- The primary objective was to determine and measure bone strain magnitudes and directions at various positions of the humerus in a controlled laboratory setup, specifically focusing on the donor site for bone grafts (a site prone to stress fractures), and the middle of the humerus diaphysis.
- The secondary objective was to check if computing strains solely in the direction of the humerus’s longitudinal axis in the mathematical model was limited, by comparing these with the principal strain magnitudes and directions.
- The final objective was to validate whether the mathematical model formulated in Part I of this research was effective at determining surface bone strains. This was done by comparing the predicted strains with experimental measurements.
- Strain gauges were applied at various locations on the humerus using a controlled laboratory setup. The biceps brachii muscle and load-bearing shoulder muscles (predicted active by the model) were also included in the study.
Findings and Results
- Strains computed solely based on the direction of the longitudinal axis were found accurate for six out of eight tested locations on the humerus. However, for the cranial and medial aspects of the diaphysis middle, the principal strain and experimental longitudinal strain did not compute accurately.
- Further verification at the six validated locations showed the mathematical model from Part I could predict strains within +/-2 standard deviations for four locations, and negligible strains for two locations, which was consistent with the experimental strains.
- Experimental strains at the humerus’s diaphysis middle suggested that tensile strains occur at the cranial aspect (front/upper part) and compressive strains at the caudal aspect (back/lower part) when the horse is standing. Such findings could benefit fracture fixation procedures.
Implications
- The study helps in better understanding and predicting strains in different parts of the equine humerus, primarily useful in the bone grafting processes and predicting potential stress fracture sites.
- The mathematical model, tested and validated in this study, may serve as a useful tool for biomechanical engineers, veterinarians, and others working in the field of <a href="/equine-rehabilitation-guide/" title="equine rehabilitation and healthcare to study and predict strain patterns effectively.
Cite This Article
APA
Pollock S, Stover SM, Hull ML, Galuppo LD.
(2008).
A musculoskeletal model of the equine forelimb for determining surface stresses and strains in the humerus-part II. Experimental testing and model validation.
J Biomech Eng, 130(4), 041007.
https://doi.org/10.1115/1.2898729 Publication
Researcher Affiliations
- Biomedical Engineering Program, University of California, One Shields Avenue, Davis, CA 95616, USA.
MeSH Terms
- Animals
- Computer Simulation
- Elasticity
- Forelimb / physiology
- Horses / physiology
- Humerus / physiology
- Models, Biological
- Muscle Contraction / physiology
- Muscle, Skeletal / physiology
- Postural Balance / physiology
- Posture / physiology
- Stress, Mechanical
- Surface Properties
Citations
This article has been cited 2 times.- van Bijlert PA, Geijtenbeek T, Smit IH, Schulp AS, Bates KT. Muscle-Driven Predictive Physics Simulations of Quadrupedal Locomotion in the Horse. Integr Comp Biol 2024 Sep 27;64(3):694-714.
- Nguyen JT, Barak MM. Secondary osteon structural heterogeneity between the cranial and caudal cortices of the proximal humerus in white-tailed deer. J Exp Biol 2020 Jun 11;223(Pt 11).
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