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EquiTest modification with shank and hip angle measurements: differences with age among normal subjects
R A Speers1, N T Shepard, A D Kuo
1Vestibular Testing Center, Dept. of Otolaryngology, University of Michigan, Ann Arbor 48109-0816, USA. rspeers@umich.edu
Journal of Vestibular Research : Equilibrium & Orientation
|January 19, 2000
Summary
This study explored using body movement (kinematics) instead of force plates for balance testing. Kinematic feedback improved detecting age-related balance differences and may enhance balance disorder diagnosis.
Area of Science:
- Biomechanics
- Neuroscience
- Gerontology
Background:
- The Sensory Organization Test (SOT) on the EquiTest system assesses sensory integration for balance using forceplate data.
- Current SOT methods rely on ground reaction forces for sway-referencing and postural sway assessment.
- Limitations exist in precisely measuring sensory utilization and postural control with forceplate-based feedback.
Purpose of the Study:
- To investigate the efficacy of kinematic measurements for sway-referencing and postural sway assessment in the SOT.
- To compare standard EquiTest sway-referencing with kinematic feedback methods (shank motion and center of mass).
- To evaluate the impact of kinematic feedback on age-related differences in balance control.
Main Methods:
- Compared three sway-referencing methods: standard EquiTest, kinematic shank motion feedback, and kinematic center of mass (COM) feedback.
- Utilized a two-link biomechanical model to calculate COM position.
- Assessed 51 healthy subjects across a wide age range (20-79 years) using a randomized protocol.
Main Results:
- Kinematic sway-referencing (shank or COM) reduced Equilibrium Quotient and Strategy Score assessments compared to the standard method across all age groups.
- Significant differences in kinematic sway measures (shank, hip, COM angle) were observed with alternative sway-referencing parameters.
- Kinematic feedback amplified age-related differences in balance control, indicating increased sensitivity.
Conclusions:
- Direct kinematic feedback for sway-referencing may improve the ability to reduce proprioceptive input by more accurately controlling ankle motion.
- Kinematic measurements offer enhanced sensitivity for detecting balance disorders by discriminating sway from acceleration and analyzing inter-segmental phase relationships.
- Kinematics provide a more direct and potentially more sensitive approach to balance assessment than traditional forceplate methods.