[A case report and metallurgical analysis of broken Luque rod]

Wire breakage is frequently mentioned in Luque rod instrumentation with segmental sublaminar wiring, but breakage of the Luque rod is rare. A case report of a broken Luque rod in a patient following a scoliosis post-corrective operation is presented and a metallurgical analysis is provided to evaluate the mechanism of breakage. In the metallurgical analysis, we find many slots and dimples on the rod surface which were induced by an inappropriate bending apparatus and bending manipulation. These defects resulted in a stress concentration effect and initiated fatigue. As for the stress on the rod, this resulted from the force correcting the scoliotic deformity plus the load resulting from patient's daily activity, which increased the progression of fatigue and then induced the final breakage. So, to avoid Luque rod breakage we suggest that the bending manipulation be done appropriately, with external orthosis given to those patients with severe deformity or who are daily very active.