Lateral to medial hamstring activation ratio: Individuals with medial compartment knee osteoarthritis compared to asymptomatic controls during gait

Derek Rutherford, Matthew Baker

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

Background: Elevated lateral hamstring activity is often found in individuals with knee osteoarthritis during gait. These findings are based on maximal voluntary isometric contraction normalized EMG signals. This choice of amplitude normalization may contribute to differential activation of the hamstrings. Research question: The objective was to determine lateral to medial hamstring root mean square activation ratios of individuals with medial compartment knee osteoarthritis compared to asymptomatic older adults during walking. The secondary objective was to determine whether this ratio differed between ipsilateral and contralateral knees in individuals with knee osteoarthritis. Methods: Surface electromyography of the hamstrings were acquired using standardized techniques from both limbs of 42 individuals with unilateral symptomatic medial compartment knee osteoarthritis and a random limb of 40 asymptomatic individuals during treadmill walking. Root mean squared amplitudes from the gait cycle were calculated. The lateral:medial activation ratio was computed. To address the first objective, an independent t-test was performed; both corrected and not corrected for walking velocity. A paired t-test was used for the second objective (alpha = 0.05). Results: The lateral:medial activation ratio was greater in the knee osteoarthritis group demonstrating a moderate effect size (p < 0.05, Cohens d = 0.73). The ipsilateral lateral:medial ratio was also greater than the contralateral (p < 0.05) in the knee osteoarthritis group, showing a low to moderate effect size (Cohens d = 0.53). Significance: The activation ratio of the lateral and medial hamstrings during treadmill walking was unique to the symptomatic leg of individuals with medial compartment knee osteoarthritis. The ratio showed a bias toward greater lateral hamstring activation in the symptomatic leg. While considerations such as the impact of subcutaneous tissue differences between electrode sites should be considered when interpreting un-normalized electromyograms, this technique may be useful in integrating electromyography into clinical knee osteoarthritis functional assessments without the requirement of maximal voluntary isometric contraction-based amplitude normalization.

Original languageEnglish
Pages (from-to)95-97
Number of pages3
JournalGait and Posture
Volume70
DOIs
Publication statusPublished - May 2019

Bibliographical note

Funding Information:
This work was supported by the Nova Scotia Health Research Foundation ( MED-DI-2014-8668 and MED-EST-2014-9605 ) and Nova Scotia Health Authority ( 2014-018 ). The sponsors had no role in the design and conduct of this study; collection analysis, and interpretation of data; preparation, review or approval of the manuscript; and decision to submit the manuscript for publication.

Funding Information:
We would like to acknowledge the Nova Scotia Health Authority and Nova Scotia Health Research Foundation for funding, Ms. Sara Saleh and Dr. Janice Moreside for assisting with data collection, Drs. Ivan Wong, William Stanish and Nathan Urquhart for recruitment efforts and our participants for taking time to help us with our research.

Publisher Copyright:
© 2019 Elsevier B.V.

ASJC Scopus Subject Areas

  • Biophysics
  • Orthopedics and Sports Medicine
  • Rehabilitation

PubMed: MeSH publication types

  • Journal Article
  • Research Support, Non-U.S. Gov't

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