Special-Purpose Orthoses for Children: A Brief Review*
Congenital Hip Dislocation and Dysplasia
For infants in the prewalking stage, several orthotic designs may be used to hold the hip in a flexion-abduction attitude, in an attempt to position and maintain the femoral head within the acetabulum. The three devices illustrated are the Pavlik harness and the Von Rosen and llfeld splints.
The Pavlik harness (Fig. 1 ) consists of a chest strap, a shoulder harness, and anterior and posterior straps that extend from the chest strap to bootees that hold the feet securely.
The Von Rosen splint (Fig. 2 ) consists of a plastic frame that is easily shaped to conform to the child's body. The superior part of the frame passes over the shoulders, the inferior part passes under the thighs, while the middle part conforms to the posterior and lateral aspects of the trunk. A horizontal strap holds the splint in place while two vertical straps hold the thighs in the desired position.
The Ilfeld splint (Fig. 3 ) consists of two thigh bands which are connected to a cross bar by universal joints. The thigh bands hold the thigh in the abducted position. The degree of abduction is controlled by adjusting the length of the cross bar. A waist band is generally used to hold the splint in place more securely.
None of these orthoses are immobilizers; that is, they all allow varying degrees of motion while accomplishing their basic purpose of imposing a flexion-abduction attitude.
Angular and Rotational Deformities
Denis Browne Splint
This orthosis consists of a variable-length spreader bar with foot plates at either end (Fig. 4 ). The infant's shoes are securely attached to the foot plates, whose rotational position is adjustable. Varus-valgus positioning of the foot is accomplished by bending the spreader bar. This simple splint is used in the management of rotational and angular deformities such as clubfoot, pronated foot, and abnormal tibial torsion.
The distal components of this orthosis are quite similar to the Denis Browne splint and serve the same purpose. To apply corrective forces for more proximal abnormalities, calf and thigh bands and pressure pads are attached to an "A"-shaped metal frame (Fig. 5 ). All components are either adjustable or available in several sizes, so that children of varying heights and girths can be accommodated.
A torsion shaft consists of a tightly coiled spring within a flexible housing, or of a flexible plastic rod. Usually the proximal end of the shaft is attached to a pelvic band with the distal end attached to the shoe (Fig. 6 ). The tension in the spring is used to apply a rotary force to the distal segments of the limb. An adjustment screw increases or decreases spring tension and thus the degree of rotary force imparted to the leg.
Use of this component may be considered in the management of mild scissors gait, spastic hemiplegia, and in some cases where there is abnormal toe-in or toe-out. However, the utilization for this type of orthosis has been seriously questioned, because of the possibility of introducing rotary stresses in areas other than those requiring correction. This problem must always be taken into consideration in utilizing a torsion-shaft orthosis.
Among the orthoses most commonly used in the management of this disease are the designs known as the Trilateral, Toronto, and Scottish Rite. All three maintain the hip in abduction so that the femoral head is well-contained within the acetabulum. The trilateral and Toronto designs also rotate the femur internally to aid containment.
The trilateral orthosis (Fig. 7 ) consists of an ischial-weight-bearing plastic brim, a single medial upright including a drop-ring knee lock, a spring loaded shoe attachment which maintains desired foot-ankle alignment, and a modified pattern bottom to transmit body weight to the floor, thus minimizing weight-bearing through the anatomic hip. The designation "trilateral" derives from the fact that the lateral wall of the plastic brim is cut away distal to the trochanter to eliminate medially directed forces which might tend to adduct the hip. Fitting of this orthosis may be unilateral or bilateral.
The Toronto orthosis (Fig. 8 ) consists of a single vertical tube whose upper end is connected to bilateral thigh cuffs and whose lower end is connected to horizontal spreader bars. The latter connection is by means of ball joints which permit each knee to flex independently. Shoe blocks are attached to high-top shoes to maintain foot-ankle alignment.
The last design the Scottish Rite (Fig. 9 ), consists of a pelvic band, two hip joints, and two thigh cuffs which are connected by a horizontal telescoping spreader bar. While this is the lightest and least restrictive of the three orthoses, it does not hold the femur in internal rotation, nor does it maintain proper alignment of the subtalar joint.
It should also be pointed out that the trilateral is the only design which can be applied unilaterally and which attempts to transmit body weight to the floor through the orthosis rather than through the hip joint.
The parapodium is a prefabricated standing frame worn over the clothes to enable young paraplegics to stand without the assistance of crutches. It consists of a springloaded shoe clamp, aluminum uprights, a foam knee block, and back and chest panels (Fig. 10 ). The orthosis has hip and knee joints which lock and unlock, thus allowing the patient to sit as well as to stand. The locks are controlled by folding handles located just below the hip joints. These handles rotate the uprights as well as the hip and knee joints of the device. For the standing position, the joint axes are aligned in the anteroposterior direction; when rotated 90 deg. the joints are free to flex. When not in use, the handles fold flat along the aluminum uprights.
*Reprinted from Lower-Limb Orthotics, 1981 Revision. Prosthetics and Orthotics, New York University Post-Graduate Medical School.