PATIENT MONITORING-SYSTEM FOR LOAD MEASUREMENT WITH SPINAL FIXATION DEVICES

Fractures of the spine can be stabilized by different implants. Their stiffness varies widely and only little is known about the loads actin g on these devices. In order to measure the forces and moments in the implant, the internal fixator after Dick was modified. An inductively powered telemery unit is placed inside the fixator and is hermetically sealed against body fluids. An integrated eight channel telemetry chi p was developed to measure the signals of six strain gauge sensors, th e implant temperature and the power supply. Because true fixators are implanted together, two telemetry transmitters run at the sane time. T his paper describes the function of the instrumented implant and the e xternal system components.