LOWERED MOTOR CONDUCTION-VELOCITY OF THE PERONEAL NERVE AFTER INVERSION TRAUMA

To analyze the effect of inversion trauma on peroneal nerve function, motor conduction velocity was measured in 22 patients. In the injured leg, 4-8 d post trauma motor nerve conduction velocity in the knee-cap ut fibulae segment of the superficial peroneal nerve was significantly smaller when compared with the contralateral leg and the control grou p. Five weeks post trauma these values were normal again. For three se gments of the deep peroneal nerve, the motor conduction velocity was s ignificantly reduced, 4-8 d post trauma, when compared with the contro l group. In the caput-ankle and knee-ankle segment, motor conduction v elocity was still significantly lowered 5 wk post trauma. Lowered ampl itudes of the Compound Motor Action Potentials of the extensor digitor um brevis muscle were found 4-8 d post trauma. No correlation was foun d between motor nerve conduction velocities and subjective clinical te sts (anterior drawer sign and (manually performed) talar tilt test). T he results of this study support the hypothesis that inversion trauma is frequently accompanied by lesions of the peroneal nerve. Motor cond uction velocity measurements can be a valuable tool in assessing more objectively functional instability of the ankle joint induced by inver sion trauma.