Radiographic evaluation of stump-socket fit.

2 Present address: Columbia Medical Center, 630 W. 168th St., New York, N. Y. 10032. The critical relationship between accurate fit of a prosthesis and amputee comfort and function constitutes the foundation of all prosthetic fitting. Consequently, one of the most important features of a lower-extremity prosthesis is the distribution of the pressures applied to the stump by the socket. Since World War II, considerable progress has been made in the design of sockets, leading to the widespread use of "total-contact" sockets for amputations at all levels. However, reliable objective information regarding the relationship of the stump to the socket below its proximal brim is masked by the opaqueness of the socket material. The use of conventional materials (e.g., chalk, talcum, clay, and lipstick) to determine the adequacy of fit and the achievement of total contact has proved of limited value in the accurate diagnosis of fitting problems. The use of X-rays as a means of checking stump-socket fit has been discussed by several investigators (1-5). Conventional X-ray films of the stump in the socket from the front and side under weight-bearing conditions have been of considerable value in determining total contact, fit, and alignment, but the films obtained by conventional techniques do not always reveal a clear demarcation between the soft tissues of the stump and the inner surface of the socket (5). A radiographic method or procedure that would consistently give an adequate visualization of the stump-socket interface would provide valuable information for the physician and for the prosthetist in fitting patients. Such a procedure would also contribute to overall knowledge in this area of prosthetics, and this knowledge would aid in teaching the proper fabrication of sockets. Some preliminary experimental work relevant to the above-stated deficiency, reported by Dr. N. C. McCollough, involved the topical application of an X-ray contrast material to the skin of the stump (5). Two or three coats of a saturated solution of sodium iodide in absolute alcohol were applied to the stump with a sponge and allowed to dry. The usual number of stump socks were then applied, the stump was inserted into the prosthesis, and films were made under weight-bearing conditions in the anteroposterior and lateral projections. The films obtained by this method provided a clear outline of the periphery of the stump, and any lack of total contact was easily recognized.