Bateman, Thomas D. A biomechanical evaluation of a novel mobile walking device Faculty Mentor: Matthew K. Seeley, Exercise Sciences Many individuals rely on crutches to help them walk. Those relying on traditional crutches often suffer from upper-extremity pathologies as well as psychological detriments. 1 Additionally, those using crutches typically suffer from increased energy expenditures during locomotion. 2 The Millennial Crutch (Figure 1) is a proposed alternative to the traditional crutch. The producers of the Millennial Crutch purport that Millennial Crutch use eliminates many of the disadvantages of traditional crutch use. The purpose of the research is to quantify and compare the energy that is transferred from crutch to patient during the stance phase of locomotion in patients using the traditional crutch and Millennial Crutch. Stance is defined as the time in which the crutch is in direct contact with the ground. It has been hypothesized that the Millennial Crutch will absorb more energy during the first half of stance, and transfer more energy to the patient during the second half of stance, in comparison to the traditional crutch. Data collection involved ten males and ten females. Thirty-five small reflective markers were placed on various anatomical landmarks, using adhesive tape, to facilitate 3-D motion analysis of the entire body via high-speed video. After the reflective markers were applied, the participants began the ambulation trials. Participants were required to complete five successful trials while using the traditional crutch and five successful trials while using the Millennial Crutch. Each trial was considered successful if: 1) the ambulation was subjectively considered representative by the researcher and participant, and 2) the ambulation occurred within ± 2.5% of a pre-determined standardized ambulation velocity. The order in which each crutch is utilized was randomized. Video data was collected using high-speed video cameras. The 3-D location of each body segment center of mass was derived from the spatial location of each reflective marker. Next, the spatial location of the whole-body center of mass was derived from the 3-D location of each body segment. Horizontal velocity, necessary for the quantification of kinetic energy, of the whole-body center of mass was derived from the aforementioned position data; this velocity was used to estimate the amount of kinetic energy transferred to and from the body during stance. Vertical displacement of the whole-body center of mass, necessary for the calculation of potential energy, was measured using similar means. This study used one independent variable, comprised of two conditions: 1) traditional crutch ambulation, and 2) Millennial Crutch ambulation. The two conditions were used to manipulate three dependent variables: 1) change in kinetic energy during the second half of the stance phase; 2) change in kinetic energy during the first half of the stance phase; and 3) the total vertical displacement of the center of mass during the entire stance phase (potential energy). The within- subjects design required each participant to perform each condition. A multivariate statistic was used to quantify the influence of the independent variable on the group of dependent variables (p = 0.05). A paired t-test was used to examine the effect of the two conditions on each of the dependent variables. The significance level (p = 0.05) for each of these post hoc comparisons was adjusted using the false discovery rate procedure.3 We were able to determine that there was a significant difference between the traditional crutch and the Millennial Crutch. Although it is concluded that the Millennial Crutch does significantly decrease energy expenditure during ambulation, there are other facets of the crutch that can be researched. It has also been hypothesized that the angle and ergonomics of the hand grip provide decreased palmer loading resulting in less wrist injuries. Data collection and analysis methods for this hypothesis are currently being discussed. The main problem that we faced was using the computer tracking system properly. It was new to the college and took quite a bit of time to get familiar enough with it to collect and analyze data. After comprehending what the program was doing, data collection was considerably easier and more accurate. This experience in research has been very valuable to me. I never realized all the details that had to be considered and precautions taken to avoid inaccurate data. My future plans involve a professional career that could very well incorporate daily research opportunities. This project has helped me understand a little of what would be required if I chose to pursue that route in my professional career. I would like to acknowledge the help of my mentor, Dr. Matthew Seeley, and all of my colleagues involved in the research.4 1. Shortell, D. (2001). The design of a compliant composite crutch. Journal of Rehabilitation Research and Development, 38(1), 23-32. 2. Sala, D. (1998). Crutch Handle Design: Effect on Palmar Loads During Ambulation. Archives of Physical Medicine and Rehabilitation, 79(11), 1473-6. 3. Benjamini, Y. & Hochberg, Y. (1995). Controlling the false discovery rate: A practical and powerful approach to multiple testing. Journal of the Royal Statistical Society B, 57(1), 289- 300. 4. Adam Roggia, Emily Stephens, Matthew Francis.
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