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The concept of a wheelchair cushion fitting clinic for the prevention of pressure sores is reviewed in the light of recent estimates of the cost of pressure sores in the U.K. A method for measuring the pressure beneath the ischial tuberosities is discussed and techniques for measuring a patient's habitual exercise frequency and seated posture are described. Results from the records of 600 spinal injury patients including Rancho Los Amigos Hospital are reported and used to demonstrate the importance of low pressure beneath the ischial tuberosities as an indicator of wheelchair cushion suitability.

The Rancho Flotation Bed provides hydrostatic support with maximum pressures over bony prominences of 15 to 25 mm Hg (measured with a pneumatic pressure transducer). This is generally below the levels normally quoted as conducive to the development of ischaemia. Clinical experience has shown the bed to be a successful aid to nursing by eliminating the need to turn the patients for pressure reasons, allowing patients with pressure sores to remain in a position which is more comfortable and more suitable for other nursing care. It also makes it easier for nurses to handle patients in order to care for the pressure sores.

A measurement technique was developed that enabled us to separate (and exclude) the effects of all viscoelastic moments from that produced by the extensor tendon itself. Knowing this moment at various joint positions allowed us to calculate the effective extensor moment arm at the proximal interphalangeal joint. Measurements made on lateral films enabled us to show which fibers of the extensor complex were tensed at various positions of the joint. The results obtained on three fresh cadaver long fingers confirmed the findings of Sarrafian-that in the flexed position, the most central fibers are tensed; whereas, in the extended position, the lateral fibers are tensed.

A new infinitely variable automatic transmission called the RESATRAN that automatically changes its speed ratio in response to load torque being transmitted is presented. A prototype has been built and tested on a conventional three-wheeled electric motor propelled wheelchair. It is shown theoretically that more than 50 percent reduction in power during hill climbing may be expected when a transmission-equipped wheelchair is compared to a direct-drive vehicle operating at the same voltage. It is suggested that with such a transmission, wheelchairs can use much smaller motors and associated electronic controls, while at the same time gaining in efficiency that results in longer operating distances for the same battery charge. Design details of the transmission and test results are presented. These results show a substantial reduction in operating current and increased distance of operation over a test course.

Rehabilitation engineering emphasizes the application of the physical, medical, allied health and social sciences to ameliorate the handicaps of persons with disabilities. A handicap is the consequence of a disability that interferes with a person's life goals in daily living, vocation, avocation and recreation. The degree of a handicap depends on the interaction of a disability and a particular environment as well as on the nature of the life goals of persons with a disability. Thus, technology can reduce a handicap by overcoming functional barriers, but it may increase a handicap by raising a person's life goals to a level that cannot yet technically be achieved, or if developed, effectively delivered. The design-development-production process and the special problems inherent in the development and distribution of technical devices for handicapped persons are discussed. The dependence of the service-delivery system on adequate information and effective evaluation of devices in meeting the needs of handicapped persons is critically examined. Recommendations to overcome barriers that interfere with the availability of the products of technology for persons with disabilities are presented. A description of research areas of technology for the handicapped is also presented.

Engineering services currently being used for spine stabilization, respiratory assist, and pressure sore prevention are discussed as well as devices under development for bowel and bladder control, reduction of contractural deformities and spasticity, and electrical stimulation of paralyzed muscles. Concepts and devices for improved function are divided into categories of: orthotic devices; environmental control systems; mobility systems; page-turning devices. A wide range of engineering devices are available but strict attention must be given to medical rationale for their use.

To demonstrate in the cadaver model that the sequence of extension of the flexed metacarpophalangeal and proximal interphalangeal joints of the intrinsic-minus finger can be explained on the basis of moment ratios about these joints, the engineering concept of free body analysis was applied. Intrinsic-minus fingers, i.e., fingers of a cadaver in which all forces exerted by the intrinsic muscles were removed, were observed to hyperextend maximally at the metacarpophalangeal joint before extension of the proximal interphalangeal joint began. Mathematical calculation of moments provides an explanation of this sequence. This study confirmed that, when an equilibrium of forces at the hyperextended metacarpophalangeal joint is reached, the proximal interphalangeal joint is incompletely extended. These forces include: (1) the proximal pull of the extensor tendon; (2) the distal loading of the extensor tendon by the flexor tendons; (3) the force preventing spanning of the laminae.

Evaluation of the Seattle Foot was the first major evaluation project undertaken by the Rehabilitation Research and Development Evaluation Unit. As a joint project with the Prosthetic and Sensory Aids Service, it not only helped to launch an important new prosthetic foot concept but also set precedents for methods and procedures to evaluate promising prototype devices and to facilitate their commercialization. A great many people contributed to this project. Fred Downs and Edward Nowack organized the service delivery of the Seattle Foot through their 44 Prosthetic Clinics in VAMCs across the nation. The clinic chiefs and the prosthetic contractors gave freely of their time to ensure that evaluation data and comments were obtained and reported. Ernest Burgess and his Prosthetic Research Study staff developed evaluation protocols on which this evaluation was based. Finally, the 486 amputee veteran subjects made the evaluation a credible reality with their thoughtful responses.