Muscle stabilization strategies in people with medial knee osteoarthritis: The effect of instability

Authors

  • Laura C. Schmitt,

    1. University of Cincinnati College of Medicine, Sports Medicine Biodynamics Center, Occupational Therapy and Physical Therapy Department, Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio 45229
    Search for more papers by this author
  • Katherine S. Rudolph

    Corresponding author
    1. Department of Physical Therapy and Program in Biomechanics and Movement Science, University of Delaware, 301 McKinly Lab, Newark, Delaware 19716
    • Department of Physical Therapy and Program in Biomechanics and Movement Science, University of Delaware, 301 McKinly Lab, Newark, Delaware 19716, Telephone: 302-831-4235; Fax: 302-831-4234
    Search for more papers by this author

Abstract

The sensation of knee instability (shifting, buckling. and giving way) is common in people with medial knee osteoarthritis (OA). Its influence on knee stabilization strategies is unknown. This study investigated the influence of knee instability on muscle activation during walking when knee stability was challenged. Twenty people with medial knee OA participated and were grouped as OA Stable (OAS) (n = 10) and OA Unstable (OAU) (n = 10) based on self-reported knee instability during daily activities. Quadriceps strength, passive knee laxity, and varus alignment were assessed and related to knee instability and muscle cocontraction during walking when the support surface translated laterally. Few differences in knee joint kinematics between the groups were seen; however, there were pronounced differences in muscle activation. The OAU group used greater medial muscle cocontraction before, during, and following the lateral translation. Self-reported knee instability predicted medial muscle cocontraction, but medial laxity and limb alignment did not. The higher muscle cocontraction used by the OAU subjects appears to be an ineffective strategy to stabilize the knee. Instability and high cocontraction can be detrimental to joint integrity, and should be the focus of future research. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1180–1185, 2008

Ancillary