Date of Award

Fall 2008

Degree Type

Thesis - Restricted

Degree Name

Master of Science (MS)

Department

Biomedical Engineering

First Advisor

Harris, Gerald F.

Second Advisor

Long, Jason T.

Third Advisor

Wang, Mei

Abstract

Optical motion analysis systems are commonly used to assess the kinematics of human gait. Information obtained through this testing can identify underlying causes for walking abnormalities. The optical motion method is currently used in presurgical planning, postsurgical follow-up, evaluation of interventions, and research investigations. A limitation of this method is the amplification of noise when kinematic data is to be used for dynamics. Therefore, it would be interesting and useful to directly measure these dynamic signals. The objective of this study was to improve the method for measuring calcaneus acceleration during gait. A triaxial, calcaneus-mounted accelerometer with three attached passive markers was integrated into the Milwaukee Foot Model (MFM) to improve the dynamic signals at the foot and ankle. First the sensor was validated using the Biodex System-3 as the gold standard. This sensor was validated for measuring g-levels ranging from 0.621g to 2.89g. Since 2.89g is midrange of the vertical acceleration seen at heel strike as previously reported, this accelerometer was considered an acceptable means for measuring dynamic acceleration in human gait. After validation, the sensor was tested on ten healthy, young-adults and measured a mean of 5.11 ± 1.39g at initial heel contact. Also, the resultant accelerations measured by the sensor and the resultant accelerations measured by the markers were compared using a paired t-test. Results showed that differences between the two data samples mainly occurred at the toe-off events Overall, the triaxial accelerometer was validated against the current gold standard and proved to be practical for use in analyzing gait dynamics of a healthy, subject population. The accelometry addition to the MFM is a noninvasive, inexpensive means of acquiring dynamic, high-frequency data that may currently be omitted from the optical data. Future directions include transforming the local accelerometer axes to the calcaneus axes with respect to global and to then compare this data to the calcaneustransformed marker accelerations. This accelometry instrumentation in conjunction with the current MFM could result in a robust foot/ankle biomechanical model that could ultimately provide new information to further characterize current foot pathologies.

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