A Prosthesis to Restore Opposition in Children with Congenital Absence of the Hand

MICHAEL H. BRYANT, M.D JOHN R. DONAHUE, M.D. JAMES F. SWEIGART, C.P.O. JAMES M. HUNTER, M.D.


Summary

This article describes a terminal device which restores opposition while maintaining sensation and control of grip strength in patients with congenital aphalangia or adactylia. In those patients who would wear a prosthesis, we found the opposition post preferred almost universally to other types of prostheses.

Introduction

The ideal prosthesis is one which restores both the motor and sensory functions of the missing limb. The usual upper-extremity prosthesis provides prehension while sacrificing sensory feedback. In the upper-extremity clinic at the Elizabethtown Hospital for Children and Youth, we have been following a small group of children with congenital deficiencies of the upper limbs. Most of the patients fall into the category of congenital adactylia, in which the carpal bones are present in varying shape and number, or aphalangia, in which the metacarpal bones are attenuated and fewer in number1. These patients usually have a sensate, mobile stump with a thick, palm-like covering of skin on the volar surface, but without the necessary opposition for grasping. Others have a proximal hemimelia with one or two digits partially or wholly present, again without the necessary opposition mechanism for grasping. We have been treating these patients with a simple device, an opposition post, which restores their prehension without loss of sensory feedback. The purpose of this article is to describe our prosthesis and report some of our short-term and long-term results.

Materials and Methods

The opposition post (Figure 1. and Figure 2. ) consists of a piece of aluminum, slightly smaller in area than the volar surface of the hand remnant. This post is attached to another aluminum bar which extends up the volar two-thirds of the forearm. The prosthesis is strapped to the forearm by two U-shaped aluminum bands and Velcro-strap closures. Usually the U-shaped band opens dorsally; but when greater stability is required, the band is rotated 90 degrees (the prosthesis is still on the volar surface of the forearm), providing a better grip on the radius and ulna, and limiting supination and pronation. Finally, the palm piece is covered with a Plastisol coating to decrease wear and increase friction. The opposition post was prescribed for 15 patients between the years 1965 and 1978. Three were lost to follow-up after the initial visit, leaving 12 patients followed for one year or more. There were three males and nine females. Six patients had partial or complete aphalangia, another four had partial or complete adactylia. One patient had bilateral proximal femoral focal deficiency with bilateral paraxial fibular hemimelia associated with amelia of the upper extremities. The remaining patient had a bilateral paraxial upper-extremity hemimelia.

Only the last two patients had bilateral deformities. The average age at initial fitting was 5.8 years. The average follow-up time was 4.2 years, and the longest follow-up was 10 years. All patients were followed by the senior author (J.H.).

Results

Of the patients who were followed more than one year, 60 per cent were still wearing their opposition post routinely (Table 1. ). Except for one child, all patients in this series were offered an alternative prosthesis which usually consisted of a wrist-disarticulation prosthesis with a Dorrance hook. Of these patients, all preferred the opposition post. The only exception was one girl who used the wrist-disarticulation prosthesis routinely in the winter, and opposition post in the summer.

We treated four patients 4 years of age or younger. One patient 3 an 1/2 years old, and another 4 years old, used the post immediately in a functional manner. A third patient was fitted at 2 and 1/2 years but did not use the post functionally until age 5. All patients who chose to use the opposition post continued to do so, most of them into their teenage years, unless they were functionally improved by surgery.

Case Report

C.S. was a 6-year-old white female who was referred to our clinic with congenital aphalangia of the right hand (Figure 3. and Figure 4. ). Roentgenographically she had remnants of the first four metacarpals (Figure 5. and Figure 6. ). There was a full range of motion at the elbow, forearm, and wrist. Two previous surgical attempts to create a web space between the first and second metacarpals had failed, and there was no independent movement of the components of her hand. No further surgery was considered, and the patient was fitted with an opposition post.

Functionally she did quite well. At the last follow-up visit she was 14 years old and was using the opposition post continuously, preferring it to the wrist-disarticulation-type prosthesis. Pinch on the affected side was 7.7 kg (17 lbs.) compared to 4.54 kg (10 lbs.) on the normal side (Figure 7. ). The distance from the opposition post to her hand in the dorsiflexed position was approximately 5 cm (2 in.) (Figure 8. ).

Discussion

Murray, et al.2, described a similar type of opposition post which consists of a rigid spatula extending from a molded polycast or laminated forearm sleeve. Our device is a little simpler in design but functionally quite similar. Murray felt that a child would use a prosthesis if it increased function and was cosmetically acceptable. In our clinic the children who rejected the opposition post did so because they had some form of rudimentary pinch and were not significantly improved by the post, or because they or their family felt it was cosmetically poor. Murray also felt that there was no aversion to any particular type of prosthesis, i.e., opposition post, Dorrance hook or hand, by those who discontinued wearing them. On the other hand, we found that those patients with adactylia or aphalangia who would use a prosthesis would almost universally prefer an opposition post to a below-elbow or wrist-disarticulation type of prosthesis. This observation resulted from the fact that sensory feedback and control of grip strength were preserved, and function was thus improved. Indeed, most of our patients did quite well.

Stump-post pinch strength was usually equal to, and occasionally greater than, thumb-index pinch on the normal side. One of our patients, not included in this series because of insufficient records, is 22 years old and is working successfully as an automobile mechanic using his opposition post full time.

References:

 

    1. Frantz, C. H., and R. O'Rahilly, Congenital skeletal limb deficiencies. J Bone Joint Surg, 9-A:327---332, March 1967.

 

  1. Murray, J. F., B. Shore, and F. Treller, Prostheses for children with unilateral congenital absence of the hand. J Bone Joint Surg, 54A:1658-1664, December 1972.