Association between degenerative spondylolisthesis and spinous process fracture after interspinous process spacer surgery.

Background Context: Spinous process fracture is a recognized complication associated with interspinous process spacer (IPS) surgery. Although occasionally identified by plain radiographs, computed tomography (CT) appears to identify a higher rate of such fractures. Although osteoporotic insufficiency fracture is considered a contraindication for IPS surgery, a formal risk factor analysis for this complication has not previously been reported.