A Simplified Ankle Joint for the Toronto Swivel Walker
W. D. Friddle, Jr., C.P.O. Leslie C. Meyer, M.D.
The habilitation of the child with congenital quadrimembral deficits is a major challenge but also is one which presents a unique opportunity for close cooperation between all members of the amputee clinic team. The many detailed and informative reports that have been published concerning these patients substantiate the need for innovative variations in treatment procedures to solve the specific problems of each individual child1-7.
Of utmost importance to these patients are balance and ambulation. The Ontario Crippled Children's Centre, using the principles of Spielrein, has carefully documented the mechanics of the swivel walker (Fig. 1 ), and has described methods of measurement and fabrication for this device (Fig. 2 and Fig. 3 )4.
We have followed these principles of fabrication and assembly which are relatively simple in the hands of a qualified prosthetist. The ankle joint of the walker, however, is complex and expensive. It is mounted between the pylon and the foot and consists of a spring-loaded cam follower which returns the foot to a neutral position. Built-in stops restrict rotation to 39 deg. forward and 11 deg. backwards.
We have found that this complex unit can be successfully replaced by a piece of the heel bumper used in a single-axis foot. This bumper is made of pure gum rubber (Fig. 4 ), and, in a sense, operates on a torsion-bar principle, effectively allowing variable rotation and making the stops unnecessary. Fig. 5 shows the position of the heel bumper in the assembly.
In treating the patient described in this report, a piece of heel bumper three inches in length and one inch in diameter was used. Bumpers are available in diameters of 1/2, 3/4, and 1 inch and provide different amounts of torsional resistance according to the size used. The length of the bumper can also be modified for variations in torsional resistance.
The patient (C. H.) for whom this modified swivel walker was constructed was a girl with quadrimembral limb deficiencies aged 18 months (born Mar. 26, 1972) with a diagnosis of (1) Meromelia, terminal transverse, distal humeral, bilateral; (2) Bilateral PFFD Aitken type D (Fig. 6 ).
The child was bright and cooperative. She was initially fitted with a pair of upper-limb prostheses with nonfunctional terminal devices. A "bucket" was fashioned and attached to a platform with small wheels thus providing a means of transportation and training in balance. She quickly adjusted to these initial pieces of equipment following which she was fitted with a modified swivel walker (Fig. 7 ).
Fig. 8 show close-up views of the finished apparatus.
It is expected that this child will soon be fitted with a functional terminal device and that ultimately she will be a candidate for externally powered upper-limb prostheses.
Fig. 1 , Fig. 2 , and Fig. 3 are reproduced from Fitting and Training Children with Swivel Walkers by W. M. Motloch, and Jane Elliott, Artif. Limbs, 10:2:27-38, Autumn 1966, with the kind permission of the publisher.
Shriners Hospital for Crippled Children Greenville, South Carolina
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