Survey of above knee (A/K) prostheses currently used in the Chugoku-Shikoku district of Japan

To determine the extent to which recent advances in biomechanical technology have been implemented and to evaluate these new technologies, 84 unilateral above knee (A/K) amputees and their prostheses were surveyed in the Chugoku-Shikoku district of Japan, especially in regard to the types, sockets and components of A/K prostheses currently in use. Background factors such as age and sex of the A/K amputees and the period after amputation were also surveyed. Of the 84 amputees surveyed, 74 (88.1%) were over 40 years old and 40 (47.6%) were over 60 years old. There were 10 women (11.9%) and 74 men (88.1%). The period after amputation was under 25 years in 58 (69.0%) cases. Regarding the type of A/K prostheses, one-third of the prostheses was of the exoskeletal type and two-thirds were of the endoskeletal type. Although the endoskeletal type is becoming more popular recently, elderly A/K amputees tend to use the exoskeletal type. Thirty-one (36.9%) had plug-fit sockets which are preferable for those who follow the Japanese practice of sitting on the floor, especially for elderly amputees. Thirty-seven (44.0%) had a lock-knee, 27 (73.0%) of which were used by amputees over 60 years old. Seventy-three (86.9%) had a single-axis ankle which is generally considered to be the most stable ankle. Thus, the most common combination of prosthetic components for elderly A/K amputees was the plug-fit socket, lock-knee joint and single-axis ankle.