A Modified Prosthesis For Elbow Disarticulation Amputees

Robert E. Tooms , M.D. Elizabeth Speltz, R.P.T. Ronney Snell, CP.


The elbow disarticulation amputee is usually fitted with a prosthesis which incorporates a standard above-elbow socket and an above-elbow figure-of-eight harness. Although the presence of the humeral condyles in this type of amputation serves the desirable function of preventing socket rotation on the stump, the condyles may also cause a fitting problem, since they produce a somewhat bulbous stump. The prosthetist must frequently make the entire socket, or at least the middle portion, larger in order to allow the amputee to get his stump all the way into it. In some cases it has been necessary to form a removable window in front of the socket to overcome this problem.

In 1962 we saw an elbow disarticulation amputee in our clinic whose stump had grown too large to allow proper seating of the stump in his standard above-elbow socket. Since the socket was in good repair otherwise, we attempted to salvage the prosthesis by removing the anterior wall of the socket and making modifications in the harness and suspension. After these alterations, the child was able to get his stump all the way in with ease, and continued to use the prosthesis for several more months before a new socket was necessary. There was excellent patient acceptance of the prosthesis, and the child voluntarily stated that he preferred it to his previous standard above-elbow prosthesis and harness.

Subsequently, we have continued to fit all elbow disarticulation amputees seen in our clinic with this type of modified prosthesis. In brief, the pertinent modifications in the fabrication of this prosthesis are as follows:

The stump is measured and fabrication initiated as for a standard above-elbow prosthesis. That portion of the anterior wall of the socket overlying the biceps muscle is then cut away, with the cut extending down to the level of the distal fourth of the stump. The lateral wall of the socket is cut down to the level of the axilla rather than extending up to the level of the acromion. Thus the medial, lateral, and posterior brim lines of the socket are level (Fig. 1 ).

The harness consists of a standard below-elbow figure-of-eight harness with a Northwestern ring and an inverted-Y strap attached to the medial and lateral socket walls for suspension. An elbow lock control strap is attached to the Northwestern ring and passes across the shoulder just medial to the anterior suspension strap (Fig. 1 and 2 ). The cable is a standard above-elbow dual-control, split-housing type.

We have utilized this modified prosthesis both for initial fitting of elbow disarticulation amputees and for socket replacements. To date we have fitted eight such prostheses to five children, as well as to an equal or greater number of adult amputees, who are not included in this study. Only one patient has preferred the standard above-elbow prosthesis to the modified prosthesis. This one exception is a congenital quadrilateral amputee who requires the stabilizing force of the anterior socket wall when he uses his upper-extremity prosthesis to rise from a sitting or lying position. This is the only disadvantage we have noted with the prosthesis thus far.

On the positive side, we have found the following advantages in using the modified elbow disarticulation prosthesis :

  1. Fitting is less complicated.

  2. Harnessing is simpler and less bulky.

  3. Suspension is actually better.

  4. The entire prosthesis is lighter and less bulky.

  5. The prosthesis is easier to don, and this phase of training is simplified.

  6. The socket is cooler and easier to clean.

  7. The socket accommodates for growth, and fewer socket changes are therefore needed.

Summary

Because of the somewhat bulbous stump produced by the humeral condyles in an elbow disarticulation amputation, various socket modifications may be necessary to insure proper fit and ease of prosthetic donning and doffing. A modified prosthesis which we have used with success in our clinic for the past four years to overcome these problems is described, with its advantages and disadvantages.

Robert E. Tooms , M.D., Elizabeth Speltz, R.P.T., and Ronney Snell, CP. are associated with the Child Amputee Clinic Crippled Children's Hospital Memphis, Tennessee.