An instrumented rod rotator

An electronically instrumented rod rotator has been developed to monitor forces and moments applied by surgeons during spinal surgery. This instrumented rod rotator consists of an inclinometer and two pairs of strain gauges with all the support circuitry. The strain gauge data and the inclinometer are sampled with a data acquisition system and the results are displayed in real time. The device has been calibrated in the laboratory and used on seven patients. The precision of the load measurement of this device is /spl plusmn/5 N in the range of 5 to 65 N. The maximum loads applied by the surgeon during those seven surgeries are from 20 to 60 N with a torque from 4 to 11 Nm.