A TRANSDUCER FOR THE MEASUREMENT OF FORCES IN EXTERNAL FRACTURE FIXATOR DEVICES - TEST-RESULTS

This communication presents a force sensor that has been developed and adapted to a bone-fracture external fixator system. This strain gage sensor measures the vertical force transmitted through the external fi xator device; non-desired effects are minimized. This sensor has been employed for the establishment of conclusions in the limb-lengthening field. This paper includes two kinds of tests carried out with two sen sorized fixators. First, the fixator is tested on a dynamic machine in order to obtain its calibration. Secondly, results of some in vivo te sts are presented. The elongation imposed is 1 mm per day; elongation forces are measured. In this experimental work the force sensor has be en used to establish a time-dependent relation between the callus leng th and the force transmitted through the fixator.