Dynamic stability margin using a marker based system and Tekscan: a comparison of four gait conditions.
Stability during gait is maintained through control of the center of mass (CoM) position and velocity in relation to the base of support (BoS). The dynamic stability margin, or the interaction of the extrapolated center of mass with the closest boundary of the BoS, can reveal possible control errors during gait. The purpose of this study was to investigate a marker based method for defining the BoS, and compare the dynamic stability margin throughout gait in comparison to a BoS defined from foot pressure sensors. The root mean squared difference between these two methodologies ranged from 0.9 cm to 3.5 cm, when walking under four conditions: plantigrade, equinus, everted, and inverted. As the stability margin approaches -35 cm prior to contralateral heel strike, there was approximately 90% agreement between the two systems at this time point. Underestimation of the marker based dynamic stability margin or overestimation of the pressure based dynamic stability margin was due to inaccuracies in defining the medial boundary of the BoS. Overall, care must be taken to ensure similar definitions of the BoS are utilized when comparing the dynamic stability margin between participants and gait conditions.
Motion Analysis Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, MN 55905, USA.
Vipul
V
Lugade
Motion Analysis Laboratory, Division of Orthopedic Research, Mayo Clinic, Rochester, MN 55905, USA. Electronic address: kaufman.kenton@mayo.edu.
Kenton
K
Kaufman
D000328:Adult; D001696:Biomechanical Phenomena; D004867:Equipment Design; D005260:Female; D005528:Foot / Q000502:physiology*; D005684:Gait / Q000502:physiology*; D006365:Heel / Q000502:physiology; D006801:Humans; D008297:Male; D018670:Monitoring, Ambulatory / Q000295:instrumentation*; D009989:Orthotic Devices; D004856:Postural Balance / Q000502:physiology*; D011312:Pressure; D012016:Reference Values; D014160:Transducers, Pressure; D016138:Walking
Base of support; Dynamic stability; Gait; Motion analysis; Pressure sensors