The anterior tibial, gastrocnemius, and many other of the artificial muscles devised by Duchenne are still in use in the modified form given to them by Barwell. On the other hand, the action of the long peroneus in pronating the foot, and which Duchenne imitated by an elaborate artificial tendon following the exact course of the natural one, is to-day generally supplemented by the jointed shoe and laced bandage.
In paralysis of all the muscles surrounding a joint, when the limb is placid and no retractions by adapted atrophy have taken place, the artificial muscles can only serve to oppose the malpositions which are threatened from mechanical influences.
In the upper extremities prothetic apparatus has been principally used for progressive muscular atrophy. Paralysis of the wrist extensors is perhaps the only case in which the artificial muscle is required in anterior poliomyelitis. A string may be necessary to support the arm in paralysis of the deltoid, to avert luxation of the humerus.
Duchenne's ingenuity did not shrink from the difficult task of supplementing the muscles of the trunk. This he did by inserting the elastic spirals in corsets in a direction following that of the muscles paralyzed. Thus, a unilateral paralysis of the sacro-lumbalis may be met by a spiral splint running up one side of the spine; below, to the lateral posterior portion of a pelvic girdle. In bilateral paralysis two springs are used to antagonize the action of the abdominal muscles.
In Barwell's apparatus for the trunk184 India-rubber bands are again substituted for spiral springs. No attempt is made to imitate the direction of muscles, but the force is applied in any direction required to antagonize the pressure producing the deformity.185
184 Especially designed for habitual scoliosis, but applicable also to the paralytic deformity.
185 Volkmann (loc. cit., p. 778) thinks that the force of Barwell's India-rubber straps, whether for scoliosis or club-foot apparatus, is inadequate, and much inferior to metallic springs.
It is always important to remember the rarity of scoliosis caused by spinal paralysis of the trunk-muscles, and the much greater frequency with which this deformity occurs as a consequence of the paralytic shortening of a leg. A high shoe, equalizing the length of the lower extremities, is then the simple and efficient remedy.
In cases of long standing, even when the scoliosis is due to this cause, certain muscles on the concave side of the curve may become so retracted and rigid as to require tenotomy. Before this operation it is necessary to put the rigid muscles on the stretch as much as possible; and this may be done, if necessary, by means of Sayre's hanging apparatus. After this operation the spine may be straightened out with ease—an important distinction from advanced habitual scoliosis, where the alteration in the shape of the vertebræ defeats all attempts at rectification. The position may be maintained by elastic straps or corsets and by removing the condition which has led to the deformity.
Seeligmüller criticises too unfavorably the entire system of elastic tension in the prophylaxis and treatment of paralytic deformities. He quotes Duchenne's admission, that in certain cases traction upon rigidly-retracted tissues becomes insupportably painful, and must be abandoned. It is in these cases that tenotomy becomes an indispensable preliminary to the use of apparatus. Sayre insists that the necessity for tenotomy is indicated when pressure on the rigid muscle is followed by instantaneous spasmodic contraction in the affected or neighboring muscles. He declares that such contractions indicate reflex irritations, show that the muscle has undergone structural change, and that any attempt to stretch or lengthen it would be followed by an excess of irritation and pain.