Changes in Passive Mechanical Properties of the Gastrocnemius Muscle at the Muscle Fascicle and Joint Levels in Stroke Survivors

Gao, Fan; Grant, Thomas H.; Roth, Elliot J.; Zhang, Li-Qun

doi:10.1016/j.apmr.2008.11.004

« Previous Next »Archives of Physical Medicine and Rehabilitation
Volume 90, Issue 5 , Pages 819-826, May 2009

Changes in Passive Mechanical Properties of the Gastrocnemius Muscle at the Muscle Fascicle and Joint Levels in Stroke Survivors

Fan Gao, PhD
- Rehabilitation Institute of Chicago, Chicago, IL
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL
- Department of Health and Kinesiology, University of Texas at Tyler, Tyler, TX
Thomas H. Grant, MD
- Department of Radiology, Northwestern University, Chicago, IL
Elliot J. Roth, MD
- Rehabilitation Institute of Chicago, Chicago, IL
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL
Li-Qun Zhang, PhD
- Rehabilitation Institute of Chicago, Chicago, IL
- Department of Physical Medicine and Rehabilitation, Northwestern University, Chicago, IL
- Department of Orthopaedic Surgery, Northwestern University, Chicago, IL
- Department of Biomedical Engineering, Northwestern University, Chicago, IL
- Reprint requests to Li-Qun Zhang, PhD, Rehabilitation Institute of Chicago, Ste 1406, 345 E Superior St, Chicago, IL 60611

Abstract

Gao F, Grant TH, Roth EJ, Zhang L-Q. Changes in passive mechanical properties of the gastrocnemius muscle at the muscle fascicle and joint levels in stroke survivors.

Objectives

To investigate the ankle joint–level and muscle fascicle–level changes and their correlations in stroke survivors with spasticity, contracture, and/or muscle weakness at the ankle.

Design

To investigate the fascicular changes of the medial gastrocnemius muscle using ultrasonography and the biomechanical changes at the ankle joint across 0°, 30°, 60°, and 90° knee flexion in a case-control manner.

Setting

Research laboratory in a rehabilitation hospital.

Participants

Stroke survivors (n=10) with ankle spasticity/contracture and healthy control subjects (n=10).

Interventions

Not applicable.

Main Outcome Measurements

At the muscle fascicle level, medial gastrocnemius muscle architecture including the fascicular length, pennation angle, and thickness were evaluated in vivo with the knee and ankle flexion changed systematically. At the joint level, the ankle range of motion (ROM) and stiffness were determined across the range of 0° to 90° knee flexion.

Results

At comparable joint positions, stroke survivors showed reduced muscle fascicle length, especially in ankle dorsiflexion (P≤.048) and smaller pennation angle, especially for more extended knee positions (P≤.049) than those of healthy control subjects. At comparable passive gastrocnemius force, stroke survivors showed higher fascicular stiffness (P≤.044) and shorter fascicle length (P≤.025) than controls. The fascicle-level changes of decreased muscle fascicle length and pennation angle and increased medial gastrocnemius fascicle stiffness in stroke were correlated with the joint level changes of increased joint stiffness and decreased ROM (P<.05).

Conclusions

This study evaluated specific muscle fascicular changes as mechanisms underlying spasticity, contracture, and joint-level impairments, which may help improve stroke rehabilitation and outcome evaluation.

Key Words: Contracture, Muscle spasticity, Rehabilitation, Stroke

List of Abbreviations: ACSA, anatomical cross-sectional area, ROM, range of motion

Supported by the National Institutes of Health (grant nos. HD044295 and HD043664).

No commercial party having a direct financial interest in the results of the research supporting this article has or will confer a benefit on the authors or on any organization with which the authors are associated.

PII: S0003-9993(09)00078-1

doi:10.1016/j.apmr.2008.11.004