Complications and strategies for salvage of intervertebral fixation devices.

The recent evolution of interbody fixation devices, known as threaded interbody fusion cages, is a significant new form of segmental fixation for application to the lumbar and lumbosacral spine. This article discusses the construction, biomechanics, and use of these devices, which serve as carriers for autogenous graft material while restoring segmental stability to the involved motion segment. The biomechanics of these devices greatly surpasses those of the interbody spacers used historically. Interbody spacers have traditionally been utilized as a component of an overall construct that also employed segmental posterior instrumentation. Threaded interbody cages, on the other hand, are able to confer a degree of stability to the diseased motion segment as stand-alone constructs.