Effects of sagittal postural adjustments on seat reaction load

• Published in: Journal of biomechanics Vol. 41; no. 10; pp. 2237 - 2245
• Main Authors: van Geffen, Paul, Reenalda, Jasper, Veltink, Peter H, Koopman, Bart F.J.M
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 19.07.2008; Elsevier Limited
• Subjects: Adult; Biomechanical Phenomena - methods; Buttock pressure; Buttocks; Ergonomics; Health care policy; Humans; Imaging, Three-Dimensional; Influence; Male; Movement - physiology; Pelvis - pathology; Personal relationships; Physical Medicine and Rehabilitation; Posture; Pressure; Pressure Ulcer; Pressure ulcers; Seating force; Sitting posture; Stress, Mechanical; Weight-Bearing; Wheelchair adjustment; Wheelchairs; Seating force; Pressure ulcers; Wheelchair adjustment; Sitting posture; Buttock pressure
• ISSN: 0021-9290; 1873-2380
• DOI: 10.1016/j.jbiomech.2008.04.012

Abstract Wheelchair-dependent subjects often adopt a passive sitting posture and suffer from sitting acquired pressure ulcers (PU) that mainly occur when high buttock pressures sustain for a longer period of time. Body posture directly influences seating load and proper postural change is therefore essential. Many subjects cannot reposition themselves and seating systems that adjust sitting posture can regulate seating load and potentially diminish the risk to develop PU. We describe a mechanism for postural adjustments and investigated the influence of seat inclination (1), pelvis rotation (2) and chair recline (3) on buttock load. We developed an experimental simulator chair containing the concept to adjust body posture in the sagittal plane. Measurements involved quasi-static actuated chair movements in which chair configuration, buttock interface pressure and seating forces were simultaneously measured. Significant effects with high coefficients of determination ( r2 >0.8) were found for seating force, centre of pressure and sacral load. We conclude that a combination of independent pelvis rotation and seat inclination is effective to regulate the net buttock shear force and the sacral interface pressure in healthy subjects. Whether both techniques are also applicable in subjects without postural stability is still to be evaluated.