IN-VITRO LOAD MEASUREMENT USING AN INSTRUMENTED SPINAL FIXATION DEVICE

An AO spinal fixateur interne was modified to study tile effects of a corpectomy on implant performance. A hermetically sealed cartridge con taining strain gauges and an inductively Powered telemetry unit was in tegrated into the threaded portion of the original implant. Five cadav eric spines were instrumented with the modified implant spanning a sin gle lumbar vertebra. The spines were tested in axial compression, tors ion, flexion, extension and lateral bending: Measurements of the three forces and moments within the implant were performed in the intact sp ine and repealed following a corpectomy and corpectomy plus complete p osterior ligamentous injury. The bending moment increased following co lpectomy in all testing modes. The largest increase was in the flexion Dt bending moment, which increased SI om 155 Nmm to 3328 Nmm followin g corpectomy. Copyright (C) 1996 Elsevier Science Ltd for IPEMB.