Design and development of a pressure relief seating apparatus for individuals with quadriplegia

Persons with spinal cord injury above C7 lack the ability to extend their elbows and grip with their hands. Consequently, when seated, they are unable to press down to shift their weight to relieve pressure on the ischial tuberosities. This can ultimately cause serious pressure sores to develop on the buttocks. Those with adequate insurance coverage can eliminate this problem with an electric power recliner wheelchair. With the touch of a button, the backrest will fold down to a laying position, thus relieving the pressure on the ischial tuberosity. Unfortunately, not all individuals with quadriplegia possess this type of coverage. Therefore, the problem requires an alternate design that will utilize mechanical rather than electrical power to produce a cost-effective solution. The purpose of this project was thus to design and build an affordable apparatus adaptable to wheelchairs that allows individuals with quadriplegia to shift their weight from one side to the other thus relieving the pressure on the ischial tuberosities. A pneumatic system that utilizes two inflatable air bladders was employed. One cushion is placed under each buttock and inflated separately to tilt the user from one side to the other. The inflated cushion elevates one side of the buttock, which relieves the pressure from the other side. The power required to operate the system is generated using repetitions of elbow flexion. The system was evaluated on an individual with C6 quadriplegia. The subject demonstrated independent pressure relief without intrusion on cosmesis or independence.