title: Biomechanical evaluation of a novel wheelchair backrest for elderly people.
abstract: BACKGROUND
  Back pain is a common complication of wheelchair-bound elderly people. Seating system is a key factor that influences spinal curvature, back muscle activation, interface pressure, and comfortability. A seating system can maintain lumbar lordosis, lower back muscle activity, and decrease ischial tuberosities pressure, which reduces spinal load and directly influences sitting comfort. Our previous study has confirmed that backward thoracic support showed a relatively higher lumbar lordosis and lower back muscle activity. This study intends to evaluate the influence of backward thoracic support on interface pressure and subjective discomfort.
  
  
  METHODS
  In this study, 18 elderly men were recruited to participate in a random comparison involving 4 sitting postures. These postures comprised relaxed slouching, flat back support, prominent lumbar support, and backward thoracic support sitting. All parameters, including interface pressure (total contact area, average pressure, and peak pressure on backrest and seat) and subjective discomfort (upper-back, mid-back, lower-back, buttocks, and thighs) were measured and compared.
  
  
  RESULTS
  The results showed that compared with other sitting postures, backward thoracic support sitting significantly reduced average pressure and peak pressure on seat and increased average pressure and peak pressure on backrest. Concurrently, subjective discomfort in the upper-back, mid-back, lower-back, and buttocks were reduced.
  
  
  CONCLUSIONS
  The results confirmed that backward thoracic support can maintain favorable wheelchair sitting posture, thereby preventing or reducing the risks of back pain. However, this study was no evaluations on shear forces on butts and neck postures. Future studies investigating shear forces on butts and neck postures are required.
authors.affiliation: Department of BioMedical Engineering, National Cheng Kung University, No.1, University Road, Tainan City, 701, Taiwan. p8897109@mail.ncku.edu.tw.
authors.forename: Chun-Ting
authors.initials: CT
authors.lastname: Li
authors.affiliation: Department of BioMedical Engineering, National Cheng Kung University, No.1, University Road, Tainan City, 701, Taiwan. ntwolfntw@yahoo.com.tw.|Department of Orthopaedic Surgery, Tainan Municipal Hospital, No.670, Chongde Rd., East Dist., Tainan City, 701, Taiwan. ntwolfntw@yahoo.com.tw.
authors.forename: Chih-Hsien
authors.initials: CH
authors.lastname: Chen
authors.affiliation: Department of BioMedical Engineering, National Cheng Kung University, No.1, University Road, Tainan City, 701, Taiwan. yennien.chen@gmail.com.
authors.forename: Yen-Nien
authors.initials: YN
authors.lastname: Chen
authors.affiliation: Department of BioMedical Engineering, National Cheng Kung University, No.1, University Road, Tainan City, 701, Taiwan. cchang@mail.bme.ncku.edu.tw.
authors.forename: Chih-Han
authors.initials: CH
authors.lastname: Chang
authors.affiliation: Graduate Institute of Mechatronic System Engineering, National University of Tainan, 33, Sec. 2, Shu-Lin St., Tainan, 70005, Taiwan. khnutn@gmail.com.
authors.forename: Kuen-Horng
authors.initials: KH
authors.lastname: Tsai
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000886:Anthropometry; D001416:Back Pain / Q000503:physiopathology / Q000517:prevention & control; D002081:Buttocks; D004867:Equipment Design; D006804:Ergonomics; D006801:Humans; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology; D019547:Neck Pain / Q000503:physiopathology / Q000517:prevention & control; D011187:Posture; D011312:Pressure / Q000009:adverse effects; D013131:Spine / Q000503:physiopathology; D014910:Wheelchairs