Soft Tissue Mechanics Laboratory

Intramuscular Pressure Measurements and Modeling


This is a collaborative project that has been ongoing with Mayo Clinic since 2005. This project includes the use computational and experimental tools to understand muscle pressure and material properties.


Peripheral neuromuscular diseases (PND), which cause muscle weakness, affect millions of people worldwide. Characterization of individual muscle weakness is currently performed with electromyogram (EMG) measurement, which fails to quantify muscle force. Measurement of intramuscular pressure (IMP) of interstitial fluid is a much more appropriate method to evaluate muscle mechanics, as it has been shown to correlate with force in both passive and active muscle. Current surgical procedures to correct PND are very subjective due to the inability to characterize the passive force of individual muscles. However, a pressure micro sensor could be used to measure IMP and thus gauge individual muscle force.

This figure shows an image of the fiber optic pressure sensor being developed for measurement of intramuscular pressure.


Before IMP can be incorporated into the operating room, we must understand how it behaves. Thus, the goal of this project is utilize multiple techniques to construct a finite element model of skeletal muscle that predicts IMP. The development of the model will include multiple muscle groups, tendon, bone, and skin, thus creating a physiologically accurate in situ environment.

Finite element model of excised skeletal muscle. Model is strained to 10% over a period of 0.3 seconds and displays a contour plot of Von Mises stress.


Experimental testing (tensile test is shown) of skeletal muscle to determine mechanical properties. A continuum mechanics based approach is applied to the resulting data and implemented into a finite element model.

Experimental testing is used to determine of mechanical properties of tissue and quantify fluid flow throughout muscle. This experimental work is incorporated into finite element software to develop and validate a model of skeletal muscle. The behavior of passive (relaxed), active (contracted), and weakened muscle is derived through continuum mechanics. Optimization procedures and inverse finite element techniques are incorporated for model development and implementation.
The completion of this model will yield a new tool to improve clinical and research practices, such as:

  • Patient-specific surgical or rehabilitative planning through localized modeling
  • Diagnosis of weakened and/or diseased skeletal muscle
  • Surgical procedures involving skeletal muscle
  • Whole body musculoskeletal modeling

 

 

 


Soft Tissue Mechanics Laboratory
Attn: Dr. Tammy L. Haut Donahue
1374 Campus Delivery
Fort Collins, CO 80523
phone:(970) 491-1319
email: Tammy.Donahue@ColoState.edu