Electromyographic Studies on Recoördination of I eg Movements in Poliomyelitis Patients With Transposed Tendons. ∗

Man, in contrast to lower mammals, 1 can retime the action phase of a transposed muscle in accordance with its new function. Just how this occurs, is largely unknown. A systematic investigation of “recoordination,” therefore, offers points of great theoretical and practical interest. A first report of our results is herewith presented.

Technic. The muscular action potentials were amplified in an ordinary vacuum tube amplifier set and recorded by an electromagnetically driven stylus writing on “Teledeltos” paper. Before entering the recorder, the amplified action currents passed through rectifying and integrating sets, partially summating and integrating individual spikes so as to give an estimate of the intensity of the contraction. Three identical channels were in operation, admitting independent simultaneous recording from three muscles. Provisions were made for the synchronization of these records with motion pictures. The electrodes consisted of copper mesh embedded in moist agar pads and strapped to the skin, cca 1 inch apart. Needle electrodes inserted through the skin did not prove significantly superior to surface leads. Elaborate precautions and checks were devised to guard against leakage of current from other than immediately subjacent muscles.

Tests. For the sake of standardization, the tests were restricted to a single type of operation, namely, transposition of the tendon of the M. biceps femoris to the extensor side of the knee joint to substitute for the weakened or lost action of a paralyzed M. quadriceps. The action of the transplant was to be compared with its preoperative flexor and extensor relations. The muscles chosen to represent the knee extensor and flexor group were the residual M. rectus femoris and the inner hamstrings, respectively. The action phases of these muscles during a number of standardized test performances (simple voluntary movements on command, resisted and unresisted; from prone, supine, seated, standing position; stretch reflexes; walking; bicycling; stooping, etc) were determined in both normal and polio-myelitic (unoperated) individuals.