Identifying characteristic back shapes from anatomical scans of wheelchair users to improve seating design.

Spinal deformities are common in people who require the use of a wheelchair for mobility as a result of spinal cord injuries and other disabilities. Sitting positions vary between individuals with disabilities who use wheelchairs and individuals without disabilities. In individuals with spinal cord injury, spinal deformities can result in the development of back contours that deviate from the shape of standard rigid back support shells. The purpose of this study was to distinguish and classify various back contours of wheelchair users by utilizing digital anatomic scanning technology in order to inform the future development of back supports that would enhance postural support for those with spinal deformities. The three dimensional (3D) locations of bony landmarks were digitized when participants were in position, using a mechanical wand linked to the FastScan(tm) system commonly used to measure surface contours. Raw FastScan(tm) data were transformed according to bony landmarks. A total of 129 individuals participated in this study. A wide range of back contours were identified and categorized. Although participant characteristics (e.g., gender, diagnosis) were similar amongst the contour groups; no one characteristic explained the contours. Participants who were seated in a forward lean position had a higher amount of pelvic obliquity compared to those seated in an upright position; however, participants' back contour was not correlated with pelvic obliquity. In conclusion, an array of different back shapes were classified in our cohort through 3D laser scanning technology. The methods and technology applied in this study could be replicated in future studies to categorize ranges of back shapes in larger populations of people with spinal cord injuries. Preliminary evidence indicates that customized postural support may be warranted to optimize positioning and posture when a standard rigid shell does not align with contours of a person's back. To optimize positioning, a range of contoured rigid backrests as well as height and angle adjustability are likely needed.

[1]  S E Solomonidis,et al.  Management of scoliosis with special seating for the non-ambulant spastic cerebral palsy population--a biomechanical study. , 2003, Clinical biomechanics.

[2]  Shirley G Fitzgerald,et al.  Assessing the influence of wheelchair technology on perception of participation in spinal cord injury. , 2004, Archives of physical medicine and rehabilitation.

[3]  Matthew B. Parkinson,et al.  MODELING VARIABILITY IN TORSO SHAPE FOR CHAIR AND SEAT DESIGN , 2008, DAC 2008.

[4]  D A Hobson,et al.  Postural changes with aging in tetraplegia: effects on life satisfaction and pain. , 1998, Archives of physical medicine and rehabilitation.

[5]  Peter W. Jones,et al.  Clinical and Radiographic Predictors of Scoliosis in Patients with Myelomeningocele , 2002, The Journal of bone and joint surgery. American volume.

[6]  Lisa A. Harvey,et al.  Management of Spinal Cord Injuries: A Guide for Physiotherapists , 2008 .

[7]  R Aissaoui,et al.  Evaluation of the new flexible contour backrest for wheelchairs. , 2000, Journal of rehabilitation research and development.

[8]  M. Boninger,et al.  Surface electromyography activity of trunk muscles during wheelchair propulsion. , 2006, Clinical biomechanics.

[9]  Peter J Keir,et al.  Effects of backrest design on biomechanics and comfort during seated work. , 2007, Applied ergonomics.

[10]  Rachid Aissaoui,et al.  Effect of system tilt and seat-to-backrest angles on load sustained by shoulder during wheelchair propulsion. , 2006, Journal of rehabilitation research and development.

[11]  M Kolich,et al.  Ergonomics modelling and evaluation of automobile seat comfort , 2004, Ergonomics.

[12]  Pierre Badin,et al.  Three-dimensional linear modeling of tongue: Articulatory data and models , 2006 .

[13]  Alicia M Koontz,et al.  Filter frequency selection for manual wheelchair biomechanics. , 2002, Journal of rehabilitation research and development.

[14]  Hans Tropp,et al.  Back Pain and Spinal Deformity-Common Among Wheelchair Users with Spinal Cord Injuries , 1996 .

[15]  Kersti Samuelsson,et al.  Wheelchair seating intervention. Results from a client-centred approach , 2001, Disability and rehabilitation.

[16]  S. Koop,et al.  Scoliosis in cerebral palsy , 2009, Developmental medicine and child neurology.

[17]  Helena Saraste,et al.  Measuring seating pressure, area, and asymmetry in persons with spinal cord injury , 2004, European Spine Journal.

[18]  A Delisle,et al.  Effect of pelvic tilt on lumbar spine geometry. , 1997, IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society.

[19]  Mohsen Makhsous,et al.  Sitting with Adjustable Ischial and Back Supports: Biomechanical Changes , 2003, Spine.

[20]  M Arcan,et al.  Modeling the body/chair interaction - an integrative experimental-numerical approach. , 2000, Clinical biomechanics.

[21]  Rory A Cooper,et al.  Pressure mapping to assess seated pressure distributions and the potential risk for skin ulceration in a population of sledge hockey players and control subjects , 2013, Disability and rehabilitation. Assistive technology.

[22]  Peter Vink,et al.  Effects of differences in office chair controls, seat and backrest angle design in relation to tasks. , 2009, Applied ergonomics.

[23]  D M Brienza,et al.  Seat cushion design for elderly wheelchair users based on minimization of soft tissue deformation using stiffness and pressure measurements. , 1996, IEEE transactions on rehabilitation engineering : a publication of the IEEE Engineering in Medicine and Biology Society.

[24]  M. Brault,et al.  Americans With Disabilities: 2005 , 2008 .

[25]  Franz Konstantin Fuss,et al.  Identification of design requirements for rugby wheelchairs using the QFD method , 2010 .

[26]  R A Cooper,et al.  Manual wheelchair pushrim biomechanics and axle position. , 2000, Archives of physical medicine and rehabilitation.

[27]  Stephen P Burns,et al.  Wheelchair configuration and postural alignment in persons with spinal cord injury. , 2003, Archives of physical medicine and rehabilitation.

[28]  Matthew P Reed,et al.  Development of a Methodology forSimulating Seat Back InteractionUsing Realistic Body Contours , 2011 .

[29]  R. Ferrari,et al.  Sitting biomechanics, Part II: optimal car driver's seat and optimal driver's spinal model. , 2001, Journal of manipulative and physiological therapeutics.

[30]  E N Corlett,et al.  Background to sitting at work: research-based requirements for the design of work seats , 2006, Ergonomics.

[31]  H. Saraste,et al.  Clinical evaluation of seating in persons with complete thoracic spinal cord injury , 2003, Spinal Cord.

[32]  D. Hobson,et al.  Seated Lumbar/Pelvic Alignment: A Comparison Between Spinal Cord-Injured and Noninjured Groups , 1992, Spine.

[33]  Kai-Ming G. Fu,et al.  Standardized Measures of Health Status and Disability and the Decision to Pursue Operative Treatment in Elderly Patients With Degenerative Scoliosis , 2010, Neurosurgery.

[34]  Rory A. Cooper.  Wheelchair Selection and Configuration , 1998 .

[35]  D. Harrison,et al.  Sitting biomechanics part I: review of the literature. , 1999, Journal of manipulative and physiological therapeutics.

[36]  D. Hobson.  Comparative effects of posture on pressure and shear at the body-seat interface. , 1992, Journal of rehabilitation research and development.

[37]  T M Cook,et al.  Lumbar support thickness: effect on seated buttock pressure in individuals with and without spinal cord injury. , 1992, Physical therapy.