An Archery Assistive Device For Below-Elbow Amputees

Lee Rullman


In planning and conducting a program of recreational and sports activities for our amputee children, we have frequently found it necessary to use adaptive equipment or assistive devices. This article describes an assistive device for archery that has worked quite well for our children with below-elbow amputations. We feel it has an advantage over other devices in that it makes active use of the prosthesis. Some items we have seen have simply involved the use of a bow screwed on to the artificial arm.

The archery assist (Fig. 1 and Fig. 2 ) is held by the terminal device with the hook fingers fitted into the grooves of the assist (Fig. 3 ). The bow string is held by the small tip of the assist while the archer draws the bow. The archer keeps his arm at a right angle to the body and when full draw is reached a slight rotation of the prosthesis releases the string from the archery assist, and thereby releases the arrow.

We have found it advisable for the amputee archer to use a commercially available product to hold the arrow on the string. This item consists of a pair of small rubber stoppers (arrow-nocks) generally available from any archery shop. A package of arrow-nocks costs approximately 50 cents.

The archery assist can be made from almost any available hard wood. In making our assists at this hospital we have generally used white oak since small scraps of this wood are always close at hand. The assist can be as finished or rough as the student desires. We have had some of the children finish their own archery assists and have found that they are interested in a good-looking finished product which requires much filing, sanding, and painting. In fact, making the assist can constitute a worthwhile handicraft project for the amputee.

In making the archery assist then, we start with a piece of white oak or other hard wood approximately 3 inches x 4 inches x 1 inch. The child grasps the block with his prosthetic fingers and the outline of the fingers is drawn on the block with a lead pencil. A router or a drill is then used to cut the necessary track for the fingers. A router is the preferable tool, since a drill leaves rough edges which must be chiseled away. Fig. 4 shows the dimensions and pattern used in fashioning the archery assist.

Notes On The Swivel Walker

The orignal swivel walker was described by W. M. Motloch and Jane Elliott in an Instruction Manual of the Ontario Crippled Children's Centre (October 1966)1. So far, two children, a girl aged six and a boy aged three, have been fitted. In each case ambulator-type ankle joints were used in lieu of the Canadian design. Acceptance of the walker by both children was good and proficiency was attained rapidly. It was immediately evident, however, that despite his age disadvantage the younger child performed much better owing to the presence of some upper extremities (lower-extremity amelia with congenital loss of right forearm, as opposed to quadrilateral phocomelia of the older child).

This boy had been walking in the C.D.U. (Central Development Unit) "Ambulator."

The recent fitting of a swivel walker has afforded the first real opportunity for a comparative performance test. Work is now in hand regarding fitting of articulated swivel walkers to selected patients. As small size ankle joints are essential for cosmetic appearance, some design problems had first to be overcome and the resultant units will now be fitted with modified ambulator-type ankle mechanisms incorporating rubber torsion bars.

Mr. Bob Duncan, the C.D.U. prosthetist, has suggested a modification to the swivel walker which would reduce the amount of lateral cyclic shift of the center of gravity associated with the Canadian design. In the modified version (Fig. 1 and 2 ) the "feet" are planted on the floor while the offset required for gravitational swiveling action is instead transferred to the axes of the pylons. The bucket platform is hinged from the tops of both pylon assemblies, the shift of the center of gravity past either of the hinges resulting in the elevation of the opposite "foot." As the rise of the center of gravity for a given foot elevation remains constant with either mechanism, no claim is made for greater efficiency of the proposed system in this regard. However, the reduced lateral body movement per unit time, associated with lower lateral velocity of body sway, could lower the energy consumption to a noticeable degree. This latter claim appears to be borne out by limited field trials conducted over a period of one week on a five-year-old child wearing both types of swivel walker alternatively. It is proposed to continue this work using a mechanically improved model.

Extracted from the Journal of the Repatriation Artificial Limb and Appliance Service, Victoria, Australia, Vol. 10, No. 1, April 1968.

Lee Rullman is the Activities Director of Gillette State Hospital Saint Paul, Minnesota

References:
1. Motloch, W.M., and Elliott, Jane, "Fitting and Training Children With Swivel Walkers," Artificial Limbs, 10:27-38, Autumn 1966.