Correlation between the weight of a person and the maximum stress developed by him or her while sitting for extended periods of time has been demonstrated. The lack of agreement between estimated and measured values in spinal cord injuries and Crawford's data can be mainly attributed to some sort of neurological status.

SUMMARY:Pressure ulcers are tissue damage resulting from the constant pressure on the underlying soft tissue to bony prominences for long periods. Some of the most common ulcers are developed at the ischial tuberosities area (ITs). It has been found that stresses produced in the underlying tissue to the ITs may exceed 5 to 11 times the surface stresses, making it necessary to estimate the forces generated between the soft tissue and the ITs. However, it is not possible to determine these stresses in vivo in a patient, due to ethical reasons. This paper presents a mechanical model of the pelvis-soft tissue in order to study the behavior of contact forces. The model simulates the load on the ITs of a male subject of 70 kg weight and 1.70 m height, which were recorded for 8 min. The registered forces in the model were compared with the surface forces estimated from pressure records measured by the Force Sensing Array system in a patient with spinal cord injury. After 2 min, both forces measured in the model, and the ones estimated in the patient followed the trend described by Crawford during clinical measurements of pressures during sitting. It was also found in the model that measured forces below the ITs are higher than those measured below soft tissue, which suggests that the model may be valid for the study of the forces generated inside the tissue.

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Introducción. La lesión medular afecta la calidad de vida y el estado de salud de la persona que la padece. Por su parte, el uso de una silla de ruedas adecuada a las necesidades y características particulares de cada individuo puede aumentar los cuidados en la salud, prevenir complicaciones como las úlceras por presión e incrementar la calidad de vida. Objetivo: Valorar la percepción de la calidad de vida y dar seguimiento a la formación de úlceras por presión como indicadores del impacto que tiene un programa basado en las “Pautas de suministro de sillas de ruedas manuales en entornos de menores recursos” de la OMS. Material y Métodos. A un grupo piloto de lesionados medulares se les otorgó una silla de ruedas adecuada; se les aplicaron los cuestionarios CHART-SF y WHOQOL-BREF para medir su calidad de vida y se les hizo seguimiento del desarrollo de úlceras por presión durante 12 meses. Resultados. Los principales hallazgos fueron una mejor percepción de la movilidad en el CHART-SF, mientras que en el WHOQOL -BREF el grupo no percibió ningún cambio, ni positivo ni negativo, en su calidad de vida. Los pacientes no desarrollaron úlceras por presión durante el estudio. Conclusiones. Los cuestionarios aplicados no son suficientemente sensibles para medir la calidad de vida en pacientes con lesión medular.