Residual Sagittal Motion After Lumbar Fusion

Abstract

The amount of residual flexion-extension motion with simulated lumbar fusions (presumably allowed by the bone's inherent elasticity) under physiologically comparable moments varies with fusion type and, more substantially, with varying amounts of completeness. The current study documents a range of sagittal angular motion after several types of simulated lumbar fusion that appear to have considerable overlap with previously purported radiographic criteria for solid fusion using flexion-extension radiographs. However, it also suggests the possibility that some scenarios of solid, yet incomplete, fusion may allow motion that is substantially greater than 5 degrees, which is beyond the most liberal of previously published threshold criteria.