A comparison of force exerted on rigid and dynamic backrest system by children with cerebral palsy

Katika Samaneein, Peter Greene, Karl Lees, Philip Riches

Research output: Contribution to conferencePaperpeer-review


Children with severe extensor muscle tone are expected to obtain benefit from any dynamic features of special seating. However, little evidence has been gathered to demonstrate that such users would gain functional advantages from the incorporation of dynamic components in the seating design. This project was undertaken to design a fully mobile data acquisition system to determine forces imparted by users who were children with CP on their seating during activities of daily living and, in particular, during extensor spasm. Strain gauges determined the deformations in three dimensions in key components on the backrest and footrests at 10 Hz for a period of up to 6 hours. Strain data was converted into force and moments and the resultant forces acting on the backrest and each footrest were determined. The position of the resultant force on the backrest, termed the centre of pressure (COP), was also calculated. 5 boys and 7 girls were recruited, with a mean age of 7.43 +/- 2 and a mean bodyweight of 188 +/- 40 N. No significant differences were found in the mean and peak contact force on the backrest between rigid and dynamic backrest seating components. Peak moment and average axial force on right footrest was significantly less for the dynamic system (p = 0.05 and 0.04). The average force on the backrest was 0.6 bodyweight, with 0.2 BW downward on each footrest, whilst peak forces during a strong extensor spasm were 2.5 BW on the backrest and 6 BW on a footrest.
Original languageEnglish
Publication statusUnpublished - Nov 2013
EventEuropean Seating Symposium incorporating Assistive Technology - Dublin, Ireland
Duration: 5 Nov 20138 Nov 2013


ConferenceEuropean Seating Symposium incorporating Assistive Technology


  • rigid backrest
  • dynamic backrest
  • cerebral palsy

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