Revolutionary Advances in Adaptive Seating Systems for the Elderly and Persons with Disabilities that Assist Sit-to-Stand Transfers

Abstract

The independence of elderly and arthritic patients as well as persons with disabilities is influenced considerably by their ability to stand from a chair. The presence of pain, reduced joint range of motion, stiffness, and muscle weakness often limit the ability to achieve a sit-to-stand position (STS). Realizing the enormous implications of STS performance, physicians, scientists, and industry have joined together to design and manufacture a wide variety of adaptive seating systems that facilitate therising process. These systems can be divided into three groups: those without mechanical devices, those with mechanical lifts, and those that can lift, tilt in space, recline, or rock. The design of mechanical seating systems without mechanical assists have been influenced by several factors, including chair height, armrest height, and foot position of the occupant. The evaluation of STS performance involves a variety of measurements to include joint angles and moments, speed of time to rise, functional reach and sway, and perception of patient stability (or perceived safety) in rising from a chair. These studies reported that chair seat height, use of armrest, and foot position had a major influence on the ability to do a STS movement. The use of higher chair seats resulted in lower moments at the knee and hip level. Investigators reported that lowering the chair height increased the need for momentum generation or repositioning of the feet to lower the needed moments. They found that the use of an armrest reduced the moments needed at the hip without altering the range of motion of the joints. These investigators found that repositioning of the feet influenced the strategy of STS movement, allowing lower mean extension moments at the hipwhen the foot position changed from anterior to posterior. Adaptive seating systems with lifts include the spring-booster chair spring-loaded flap seat, and ejector chair. Innovative investigators reported that increased seat height complemented by the mechanical lift enhanced STS transfers by persons with disabilities. The investigators noted that it was easier to perform STS transfer when using a mechanical lift than when rising unassisted or from a raised seat height. The latest adaptive seating system, the elevator chair, has the unique ability to assist the occupant to the STS position. The rear section of this chair remains in a fixed position to support the buttocks of the user during the mechanical lift. The front portion of the seat folds down incrementally as the chair rises to allow the feet of the user to be positioned firmly on the floor. Using an elevator chair, the height that the chair rises will vary with the length of the occupant's legs. When the user reaches a point when his/her legs are comfortably straight and the body is in an erect position, the occupant will walk unassisted from the chair. This elevator chair will soon be available with a tilt-in-space capability as well as a gently rocking motion. The elevator chairs are ideally suited for offices, waiting rooms, hospitals, long-term care facilities, and homes. While persons with disabilities appreciate the benefits of these adaptive seating systems, which allow them to achieve a STS position without assistance, healthcare personnel also value the benefits of these adaptive seating systems because they eliminate their need to lift the occupant to a standing position--an invitation for a potentially serious back injury.