A Field Study Of The Ambrl Porous Laminate Pte Prosthesis

Clyde M. E. Dolan


Summary of a report published by New York University Prosthetics and Orthotics in 1968. Copies of the complete report may be obtained from Prosthetics and Orthotics, New York University Post-Graduate Medical School, 317 East 34th Street, New York, N.Y. 10016.

In 1962, the U.S. Army Medical Biomechanical Research Laboratory (AMBRL) reported on a technique for the preparation of porous prostheses originally designed for upper-extremity applications. Although the concept was well received, strength and durability of the porous polyester formulation proved inadequate, especially when applied to lower extremity (e.g.,PTB) prostheses. In a preliminary evaluation of the polyester technique conducted by New York University, it was reported that although the porous laminate technique constituted a potentially valuable method of PTB fabrication, the results did not indicate that the optimal combination of weight, porosity and structural rigidity had been achieved. Problems noted in the fabrication process included significantly increased fabrication time, nonreproducibility of results, and curing involving two different oven temperatures.

In a redevelopment of the porous lamination technique, reported in 1966, epoxy resin was used. The new technique resulted in laminates which reportedly were: (1) two and one-half times stronger than prior products, (2) twice as porous, and (3) reproducible. They also required two hours less processing time and only a single oven temperature. On the basis of the positive results of a preliminary evaluation of the new technique, the Subcommittee on Child Prosthetics Problems recommended that NYU conduct a special workshop in the preparation of AMBRL Porous Laminate PTB prostheses, followed by a field evaluation.

Following this workshop, the technique was used in the fabrication of 20 prostheses at five participating juvenile amputee clinics in the southern section of the country during the summer of 1967. Essential aspects investigated were the fabrication process; subjective reactions of subjects, parents and clinic personnel; medical considerations; adjustments and durability.

The data indicated that porous laminate PTB prostheses were generally well accepted by patients and parents but less so by prosthetic clinic personnel. The developer's claims of reduced perspiration, added comfort, decreased dermatological problems, and lighter weight were generally corroborated; weight reduction was the most consistently reported advantage.

Increased fabrication time and some increase in the complexity of the fabrication process were cited as problems. A question concerning cosmetic characteristics elicited both favorable and unfavorable remarks; the porous laminate's propensity to collect and trap dirt particles caused some dissatisfaction, although the textured appearance of the porous laminate was preferred in some instances.

Concern was expressed regarding the durability of the porous laminate, particularly when subjected to arduous use, but experimental evidence to support this concern was apparently not recorded.

Based upon patients' and parents' preference for the experimental limbs, including instances of improvement in stump condition, it appears that the porous laminate PTB is a significant and worthwhile addition to prosthetic technology. Other applications of the porous laminate may also be appropriate, particularly for those patients with substantial body areas enclosed within a socket, with severe perspiration problems, or where a lightweight prosthesis is indicated. Shoulder caps, transthoracic sockets, above-and below-elbow sockets, or hip disarticulation and hemipelvectomy applications may be considered. Informal observations of several upper-extremity fittings have again indicated that the porous laminate offers distinct advantages in terms of decreased perspiration and weight.

The instruction manual for the preparation of the Porous PTB prosthesis has been published as U.S. AMBRL Technical Report 6804. Under the auspices of the University Council on Orthotic-Prosthetic Education (UCOPE), New York University will offer a workshop in the porous laminate technique during the coming year.

Clyde M. E. Dolan is the Assistant Project Director of Prosthetics and Orthotics at the New York University Post-Graduate Medical School New York, New York