A Dynamic Plastic Elbow- Extension Orthosis for Reduction of Flexion Contractures

The function of the elbow is to be subservient to the hand in the sense that the elbow enables the hand and fingers to be placed at desired distances from the body. Two types of motion are required to position the hand. The first, and principal one, is the shortening and lengthening of the distance the hand is positioned from the body. The hand may be brought out at full arm's length, as when the elbow is in full extension, or it may be brought up against the shoulder, as it is when the elbow is fully flexed. The second motion of the elbow adjusts the position of the hand in relation to the transverse plane by either pronation or supination. The ulnar-humeral joint, a pure hinge-type joint, allows extension and flexion motions of the elbow. Extension of the elbow is supplied by the three heads of the triceps, and some slight effort is attributed to the anconeus. The brachialis and the biceps are the two principle flexors, with the brachioradialis considered an auxiliary flexor. Spinal cord trauma, as well as a variety of neuromuscular diseases, may cause paralysis of the elbow extensors. Although gravity does assist in elbow extension, the patient that has normal or near-normal elbow flexor strength frequently suffers elbow flexion contractures owing to a lack of active elbow extension. This happens usually in quadriplegics with a lesion at the C5-6 neurological level, in which the elbow flexion is in the range of good to normal strength and the elbow extensors are absent. A well-planned program of daily exercise is re­ quired to prevent the formation of progressive contractural deformities that frequently occur when the patient no longer has physical therapy after discharge from the hospital. Various techniques and methods are used for the post-contracture treatment. Several surgical techniques which transpose muscles to improve the extensor power of the elbow may be per­ formed. Serial plaster splinting of the elbow with forced extension while casting is a simple orthotic approach. Various orthotic appliances made of metal, leather and fabric are described in the literature. These appliances have exten­ sion moment supplied by metal springs, elastic fabric, or a machine screw. A slow steady pressure is desired so that the fibrous tissue atrophies, stretches, and, in effect, grows longer. Those designs that cause an intermittent pressure such as from a sudden passive manipu­ lation may cause the fibrous tissue to hyper­ trophy if the extension is applied inexpertly. Current research at certain Rehabilitation Engineering Centers gives consideration to the elbow flexion contracture. The Annual Progress Reports of Rancho Los Amigos briefly describe research on powered orthoses that are used to extend the contracted elbow periodically. Elec­ trical stimulation of the patient's extensor mus­ cles to overcome the contracture is also receiv­ ing their attention.