Identifying characteristic back shapes from anatomical scans of wheelchair users to improve seating design
Section snippets
Background
Due to aging populations and the increased prevalence of disability, experts anticipate that the need for wheelchairs worldwide will surge [1], [2]. Consumer demand for wheelchairs that fit the personal needs, physical abilities, and functional requirements of current and expected wheelchair occupants has led to the application of sitting biomechanics and ergonomic design to the development of wheelchair components [3]. Preserving health by preventing secondary medical conditions (e.g.,
Methods
This study utilized the scanning technology known as the FastScan™ System (Polhemus, Colchester VT, USA), which features rapid recording of three-dimensional surfaces obtained by sweeping a hand-held laser scanner several times over a surface to cover the entire range of the object's surface [32]. Similar to the process of spray painting, multiple swipes are needed to measure slices of an entire surface area. This system has been used previously in clinical settings to measure the skin surface
Participants
A total of 129 individuals (average age 53.2 ± 12.0 years, and male: 109, female: 19) who used wheelchairs as their primary means of mobility participated in this study and had the following diagnoses (Table 1).
There were no significant differences between the two seated position groups based on age (p = 0.078), years of using wheelchair (p = 0.293), gender (p = 1.000), or disability (p = 0.580). For Hypothesis 1, back contour (p = 0.500) was not significantly different between the two groups. However, a
Discussion
For Hypothesis 1, although back contour was not significantly associated with sitting position, the forward lean position of participants resulted in significantly higher pelvic obliquity. Based on a sitting spinal model that was developed for the automotive industry to improve car seat design, reduction in the trunk to thigh angle led to posterior rotation of the pelvis and decrease in lumbar lordosis [36]. As the posterior buttocks and thigh muscles (e.g., gluteus maximus, hamstrings)
Study limitations
The main limitation of this study was that all participants were recruited from the National Disabled Veterans Winter Sports Clinic and the National Veterans Wheelchair Games. Participants were all active wheelchair users and may not represent the wheelchair user population. Although 18 bony landmarks were identified from the scans in this study, additional bony landmarks on the spine could have provided more detailed information about spine shapes. Moreover, in this study occupants’ backs were
Conclusion
This study established an efficient method of using digital anatomic laser scanning technology and mathematical modeling to distinguish and categorize back shapes that would be replicable with larger populations of wheelchair occupants. A range of back asymmetries were found in people who have SCI, amputation, MS, stroke, TBI, amputation and other complex disabilities. Preliminary evidence indicated that customized postural support may be warranted to optimize positioning and posture when a
Funding
Supported by The VA Center of Excellence for Wheelchairs and Associated Rehabilitation (Grant B6789C) and Paralyzed Veterans of America. The contents of this paper do not represent the views of the Department of Veterans Affairs or the United States Government.
Ethical approval
This study was approved by the VA Pittsburgh Healthcare System Institutional Review Board. Participants were recruited at the National Disabled Veterans Winter Sports Clinic and the National Veterans Wheelchair Games.
Conflicts of interest
None to declare.
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