Prosthetics and Orthotics International

Initial difficulties in producing seats for the physically disabled have led to an investigation of the process of seat prescription. An adjustable assessment chair was developed for the purpose of identifying patients' seating requirements.

The main variables of the chair's configuration are controlled by a number of hydraulic and mechanical systems.

Different support surfaces can be attached to the chair to simulate different seat characteristics. At present a bead bag vacuum consolidation system is used to simulate moulded seats.

Experience to date has shown that the assessment chair performs a valuable clinical role in the provision of seating.

A study has been performed to investigate the physical effects of lumbar spinal supports. Two groups were studied, a group of normal male subjects and a group of male low back pain patients. Five different spinal supports were investigated and their effects upon the skin temperature, spinal movements and intra-abdominal pressures of these individuals were examined. The results show surprisingly similar patterns for the widely varying designs of support. The findings also suggest that the longer term wearing of a spinal support results in a degree of physical dependence. The results of this study are aimed at improving the prescription and use of spinal supports in the treatment of low back pain.

An assessment of the material properties of three types of touch and close fasteners (Velcro) in general orthopaedic usage is presented.

The materials were tested under various loading regimes using an Instron testing machine. The force-extension curves were analyzed and values determined for both the stiffness and strength of the various attachments. Particular reference was made to the alteration in attachment strength after cyclic loading.

The strength of the standard Velcro was found to be least affected after cyclic loading to simulate continuous usage. A recommendation is made on the specific application of each type of Velcro based on their material properties.

Mechanical energy levels were investigated for normals and for below-knee amputees during level walking. The weight of the prostheses was varied by attaching 0.5 kg extra weight to the prostheses.

The measurements and analyses were made with the ENOCH system consisting of a minicomputer (HP 21 MX), an optoelectronic device for displacement data measurement (Selspot) and a force plate (Kistler) for measurement of ground reaction forces.

Results by Winter et al (1976) on the energy changes during normal walking obtained from displacement data on one leg only were verified using data from both legs and the trunk.

For the amputees it was concluded that the energy changes increased for the prosthetic shank when the weight increased. For the other body segments and for the body total no significant differences were found.

A new gait training device has been developed to provide auditory feedback of knee angle information to above-knee and hip disarticulation amputees. Traditionally, new amputees have relied on visual feedback of knee position during gait training (van Griethuysen, 1979). This auditory feedback system eliminates the need for visual feedback by providing a frequency encoded tone corresponding to knee angle.

A series of 320 amputations was analyzed with regard to wound healing complications and re-amputation rates.

Among 111 AK amputations complications in wound healing were encountered in 14 per cent (15/111) of the cases, leading to re-amputation in 2 per cent (2/111).

TK amputations were followed by wound healing problems in 30 per cent (20/66) of the cases with re-amputation in 20 per cent (13/66) at AK level, as compared to 40 per cent (57/143) with wound healing complications and 20 per cent (28/143) re-amputations in BK-amputees.

As failure of BK amputation leads to re-amputation at AK level it is recommended that the TK level be selected in doubtful cases.

Modern materials and a better understanding of the biomechanical requirements enable adaptations to shoes to be made quickly and easily in cases where the deformed foot is small enough to fit satisfactorily into standard shop-bought or standard deep footwear. A flexible self-generating polyurethane foam is used inside the shoe. It expands to the internal shape of the shoe and the external shape of the foot. It can be used either against the patient's own foot or against a positive cast of the foot. The technique has been used for 75 patients and has proved successful. The insert so made is durable and economical.

A knee-ankle-foot-orthosis has been developed that incorporates a genucentric knee joint and a similarly designed ankle joint. Its design is discussed and a clinical evaluation of its use on twenty five hemiplegic patients is presented.