Pressure-related deep tissue injury (DTI) is a life-risking form of pressure ulcers threatening immobilized and neurologically impaired patients. In DTI, necrosis of muscle and enveloping adipose tissues occurs under intact skin, owing to prolonged compression by bony prominences. Modeling the process of DTI in the buttocks requires knowledge on viscoelastic mechanical properties of the white adipose tissue covering the gluteus muscles. However, this information is missing in the literature. Our major objectives in this study were therefore to (i) measure short-term and long-term aggregate moduli of adipose tissue covering the glutei of sheep, (ii) determine the effects of preconditioning on and , and (iii) determine the time course of stress relaxation in terms of the transient aggregate modulus in nonpreconditioned (NPC) and preconditioned (PC) tissues. We tested 20 fresh tissue specimens (from 20 mature animals) in vitro: 10 specimens in confined compression for obtaining the complete response to a ramp-and-hold protocol (ramp rate of ), and 10 other specimens in swift indentations for obtaining comparable short-term elastic moduli at higher ramp rates . We found that in confined compression were and for the NPC and PC specimens, respectively. The property, , was not affected by preconditioning. The transient aggregate modulus always reached the plateau phase (less than 10% difference between and ) within , which is substantially shorter than the times for DTI onset reported in previous animal studies. The short-term elastic moduli at high indentation rates were and for the NPC and PC test conditions, respectively. Given a Poisson’s ratio of 0.495, comparison of short-term elastic moduli between the high and slow rate tests indicated a strong deformation-rate dependency. The most relevant property for modeling adipose tissue as related to DTI is found to be , which is conveniently unaffected by preconditioning. The mechanical characteristics of white adipose tissue provided herein are useful for analytical as well as numerical models of DTI, which are essential for understanding this serious malady.
Skip Nav Destination
e-mail: gefen@eng.tau.ac.il
Article navigation
December 2007
Technical Briefs
Viscoelastic Properties of Ovine Adipose Tissue Covering the Gluteus Muscles
Amit Gefen,
Amit Gefen
Department of Biomedical Engineering, Faculty of Engineering,
e-mail: gefen@eng.tau.ac.il
Tel Aviv University
, Tel Aviv 69978, Israel
Search for other works by this author on:
Einat Haberman
Einat Haberman
Department of Biomedical Engineering, Faculty of Engineering,
Tel Aviv University
, Tel Aviv 69978, Israel
Search for other works by this author on:
Amit Gefen
Department of Biomedical Engineering, Faculty of Engineering,
Tel Aviv University
, Tel Aviv 69978, Israele-mail: gefen@eng.tau.ac.il
Einat Haberman
Department of Biomedical Engineering, Faculty of Engineering,
Tel Aviv University
, Tel Aviv 69978, IsraelJ Biomech Eng. Dec 2007, 129(6): 924-930 (7 pages)
Published Online: April 19, 2007
Article history
Received:
September 7, 2006
Revised:
April 19, 2007
Citation
Gefen, A., and Haberman, E. (April 19, 2007). "Viscoelastic Properties of Ovine Adipose Tissue Covering the Gluteus Muscles." ASME. J Biomech Eng. December 2007; 129(6): 924–930. https://doi.org/10.1115/1.2800830
Download citation file:
Get Email Alerts
Related Articles
The Role of Flow-Independent Viscoelasticity in the Biphasic Tensile and Compressive Responses of Articular Cartilage
J Biomech Eng (October,2001)
A Nonlinear Model of Passive Muscle Viscosity
J Biomech Eng (September,2011)
Biphasic Poroviscoelastic Simulation of the Unconfined Compression of Articular Cartilage: II—Effect of Variable Strain Rates
J Biomech Eng (April,2001)
Determination of Homeostatic Elastic Moduli in Two Layers of the Esophagus
J Biomech Eng (February,2008)
Related Proceedings Papers
Related Chapters
Characterization of Tissue Viscoelasticity from Shear Wave Speed Dispersion
Biomedical Applications of Vibration and Acoustics in Imaging and Characterizations
Theoretical Analysis and Application of Pile Shaft Resistance Strengthening Effect
International Conference on Optimization Design (ICOD 2010)
Processing/Structure/Properties Relationships in Polymer Blends for the Development of Functional Polymer Foams
Advances in Multidisciplinary Engineering