ELECTROMYOGRAPHIC STUDY ON THE FUNCTION O F TENDON TRANSFERS IN RADIAL PALSY

The aim of this electromyographic study was to evaluate the functional result of tendon transfers for radial palsy. Eighteen patients were c ompared to 16 healthy volunteers. The intramuscular emg of four muscle s was recorded in parallel during extension-flexion movements of the w rist and fingers. The data were stored on FM tape and evaluated off-li ne. Contrary to expectations, transferred flexor muscles revealed only parr of their overall emg activity during extension. Therefore, an '' extensor quota'' (EQ) was calculated for each muscle. It reflects its emg activity during extension as part of its entire emg activity. In n on-transferred flexors EQ was low (11-27 %). High EQ Values (69-91 %) were seen in genuine extensors of healthy persons. In only 6 of 18 pat ients did transferred flexors show an EQ equivalent to genuine extenso rs (greater than or equal to 69 %). Best functional results were seen in transferred flexor carpi ulnaris (median EQ 68 %). The EQ of transf erred pronator teres was law (median 18%) and minor to flexor carpi ul naris in each patient (P < 0.05). It is concluded that in cases of rad ial palsy, pronator teres is not suitable for replacing extensor muscl es. Superficial flexors of the fingers, however, work in synergy with extensors of the wrist. According to the la reflex connections involve d, these muscles should be a good choice for regaining extension of th e wrist.