Recent advances in below-knee prosthetics.

' Executive Director, Committee on Prosthetics Research and Development, National Research Council, 2101 Constitution Ave., N. W., Washington, D.C. 20418. The concept of constructing a belowknee prosthesis with side joints and a thigh lacer was set forth by the Dutch surgeon Verduin in 1696 (Fig. 1) and followed universally until the advent of the patellar-tendon-bearing prosthesis in the late 1950's (7). Although other innovations such as contact over the distal end of the stump, suction suspension, and "muley" sockets were introduced from time to time, they were never widely used, possibly because principles governing their use were not set forth in a systematic manner. In 1957, the predecessor of CPRD, the Advisory Committee on Artificial Limbs, encouraged the University of California at Berkeley to study the problems of the below-knee amputee and to improve the then current management practices. As a result, some of the leading prosthetists in this country were invited to Berkeley later in 1957 for the express purpose of examining in detail the prosthetics practices for BK amputees and rationales for those practices (17). An analysis of the findings of that conference led to the development of the patellar-tendon-bearing prosthesis, known now as the PTB prosthesis. The original version of the PTB prosthesis was a plastic laminate socket which was formed over a modified plaster-of-Paris model of the stump, and which contained a soft inner liner that contacted the entire surface of the stump (22,23). The major weight was borne by the medial flares of the tibia and the patellar tendon. No knee joints or thigh corsets were used, suspension being effected by a fabric strap around the thigh just above the femoral condyles (Fig. 2). The PTB concept was offered in formal education programs in this country and gradually gained acceptance, so that by 1961 slightly more than half of the belowknee prostheses provided in the United States were of that type (16). The concept also has been accepted widely in other countries, and the PTB now is generally considered to be the standard prosthesis for below-knee amputations. In recent years, research groups and individual prosthetists have introduced improvements to the basic concept (6). This article describes the advanced practices in the management of the below-knee amputee that have been developed since the introduction of the PTB prosthesis.