Seat cushion optimization: A comparison of interface pressure and tissue stiffness characteristics for spinal cord injured and elderly patients

Objective: A method for designing tissue deformation minimizing seat surfaces was evaluated, Pressure and stiffness criteria were used to optimize surface shape. The method's efficacy for patients with spinal cord injuries (SCI) and a comparison of cushion performance and interface characteristics with a group of 30 elderly patients are presented. Design: Repeated measures, prospective study. Setting: University medical center. Patients: SCI (n = 12), elderly (age 65+ years) (n = 30). Interventions: One flat and two custom foam seat cushions. Main Outcome Measures: Interface pressure measured using a pressure sensing pad; tissue stiffness and pressure recorded on a rigid programmable seat surface. Results: Pressure distributions on contoured cushions for the SCI group contained lower values than distributions on flat cushions. A comparison of the pressure data between the elderly and SCI showed that significant differences exist between interface characteristics. The SCI group had higher peak interface pressures for all cushions tested. Tissue stiffness measurements were similar for each group. Conclusions: Results showed improved effectiveness of custom contoured foam seat cushions versus flat foam cushions, The results suggest that pressure distributions for SCI are more sensitive to support cushion characteristics than for the elderly. Further research is needed to determine the extent of the difference between the populations represented by these groups. (C) 1998 by American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation.