Fabrication of a Closed Syme's Prosthesis

ROBERT A. NELSON, C.P.


This report describes a method of fitting a Syme's amputation with a lighter and stronger prosthesis which has better cosmetic capabilities because of the absence of a medial or posterior opening.

These improvements are accomplished by using a medial pad or wedge to convert the bulbous-ended residual limb to a cylindrical shape ( Fig. 1 ). This pad makes it possible to use a closed cylindrical socket and still provide the necessary suspension.

The pad or wedge can be made out of any one of the many new plastic materials now available, such as Plastazote, Pelite, or AliPlast. The pad is fabricated by measuring the circumference of the distal bulbous end, and then moving up the limb with a tape measure until a point is reached at which the circumference is the same as that of the bulbous end. The area of smaller circumferences between these points is filled in with the plastic material until all circumferences are the same. This filling in is usually done on the medial side between the bulbous flare of the distal end and bulge of the soleus muscle. When working with a Syme's amputation deriving from a congenital deficiency in which there is also absence of the fibula, it will be necessary to make a pad which fully encircles the limb.

When the pad is finished it is placed in the appropriate place against the skin and covered with a cast sock ( Fig. 2 ). A second cast sock is then applied and the stump wrap-cast with plaster of Paris. For easy removal of the cast it is helpful to place a nylon stocking between the two cotton cast socks. Care should be taken to place the pad next to the skin and not between the cast socks because if this is done it will be necessary to cut the cast in order to remove it.

The cast is made by normal circumferential wrapping with plaster-of-Paris bandage. After the plaster bandage has hardened, the patient then stands and boards are placed under the cast until the desired height has been reached. While the patient stands with equal weight borne on both limbs and with about 5 deg. of flexion in the cast, a mark is made on the lateral side of the cast ( Fig. 3 ) with the aid of a plumb bob. This mark indicates the amount of flexion in the cast. The level to which the socket is to extend is also marked on the cast. These marks will be used in preparing and aligning the definitive socket.

The patient now sits down and as he. holds the first cast sock and nylon stocking, the cast is pulled off and all other appropriate measurements are taken. The pad will not be used again until the definitive limb is ready for fitting.

The negative cast is filled and the alignment line transferred to the positive mold ( Fig. 4 ). Normal cast modifications are made except in the area of the partial or full circumferential pad. The cast is screened lightly to smooth the area.

Before the laminating is done care should be taken to insure that the alignment lines will transfer to the laminated socket. The lay-up for the socket can be the same as would be used for a normal below-knee socket as it will be much stronger without a medial or posterior opening than would otherwise be the case.

After the socket is fabricated, it can be attached to the foot using the alignment and height lines for guidance. The prosthesis is now ready for dynamic fitting.

The pad is used for suspension of the prosthesis. It is placed on the patient's skin ( Fig. 5 ). A prosthetic sock is pulled over the pad and the prosthesis applied. If necessary, material can be added or removed from the pad to achieve proper fitting. Once proper fitting and alignment are achieved the prosthesis can be foamed, shaped, and laminated for better cosmesis ( Fig. 6 ).

It is advisable to provide the patient with a second pad so that it can be changed for daily cleaning.

Descriptors: AliPlast; Pelite; Plastazote; prosthesis; Syme's amputation.

Amputee Clinic, Rehabilitation Center, Children's Hospital of Buffalo, Buffalo, New York