A Soft Liner for Short Above-Elbow Double-Wall Socket Prostheses

A. R. Glaubitz, C.P.O. A. F. D'Anca, M.D. S. T. Canale, M.D.


To the best of our knowledge, the use of a soft liner in a double-wall socket prosthesis for a short-above-elbow amputee has not been previously described. An appliance of this type was recently fabricated at the State Hospital for Crippled Children at Elizabethtown, Pa., and provided a satisfactory solution to a difficult fitting problem. Other clinics may be interested in trying this fitting for similar problem cases.

Case History

S. B., a 17-year-old male, sustained electrical burns of his left upper extremity in May 1969. The severity of the injury necessitated a high above-elbow amputation. The patient was first seen at the Elizabethtown amputee clinic in November 1969.

Physical examination revealed an above-elbow amputation with a short (2-in.) stump. The stump terminated in a bony pointed prominence which was quite tender. Scar tissue was abundant, especially in the axilla (Figs. 1 and 2 ).

Initial attempts to fit this patient with a standard above-elbow prosthesis were unsuccessful because of the painful stump. In order to achieve comfortable prosthetic fitting and prevent further tissue damage from continuous irritation, a double-wall socket prosthesis with an inner foam liner was constructed.

Construction Details

A plaster impression of the amputation stump was taken. This plaster wrap was extended one-half inch above the intended trim line of the inner wall socket. The abduction and flexion angles of the stump in its normal carrying position were noted on the work sheet. A positive cast was prepared in the usual manner and a plaster-of-Paris collar was added at the top. This collar measured in-long and in. thick-this thickness being the intended thickness of the foam liner. In order to obtain a thickness that was uniform, a 3/8 in. lay-up of molding clay was applied over the cast as far up as the plaster collar. To insure that the surface would be smooth, a polyvinyl alcohol (PVA) sheet was applied over the clay lay-up.

A plaster wrap was then applied over the PVA sheet, leaving the distal end open for foaming. When the plaster wrap had set, four self-tapping screws were inserted through the wrap into the collar to insure proper replacement of the wrap on the male model. The plaster wrap was then removed from the model and its inside surface coated with parting lacquer. The clay lay-up was then removed and all debris was cleaned from the cast.

The positive cast was then covered with light chamois leather for two reasons: to give strength to the foam insert, and to serve as an inner liner of the socket. The chamois was drawn tightly over the cast and was secured above the brim of the plaster collar. The seams of this chamois were placed so as not to irritate the sensitive areas of the patient's stump. Additional strength for the liner was obtained by adding two layers of tubular gauze directly over the chamois. The plaster wrap was then refastened with the self-tapping screws to the collar of the chamois-covered plaster mold. This created an even, cone-shaped space between the plaster-of-Paris mold and the plaster wrap. Elastomer Foam was then introduced into this space from the open distal end. Seventy grams of Elastomer Foam #386 were used for the liner in this case. The plaster wrap was removed after the foam had set. The soft, inner, foam liner and plaster mold are pictured in Fig. 3 and Fig. 4 .

The excess chamois leather above the brim of the plaster collar was trimmed and cemented to the liner. If a nonremovable liner is desired, the ends of the chamois could be cemented directly to the plastic-laminated socket wall which is laid up in the usual manner. The prosthetist should remember to remove the soft liner before curing the above-elbow socket. The completed prosthesis with the foam insert is pictured in Fig. 5 .

The boy was fitted with a waist belt for elbow-lock control because with a conventional fitting he had difficulty in unlocking the elbow when the forearm was flexed to 90 deg. We attributed this difficulty to his short stump and the scar tissue around the axilla area.

With the modifications described, the patient has been able to use the prosthesis without discomfort (Figs. 6 and 7 ).

Summary

A double-wall socket prosthesis for a short-above-elbow amputee has been fabricated with a soft foam liner. The indication for the use of such a liner is a painful, tender, and bony short above-elbow amputation stump which defies fitting with standard prostheses. The method of construction of the liner has been presented.

Amputee Division, State Hospital for Crippled Children, Elizabethtown, Pennsylvania