Surgical Interbody Research Group--radiographic assessment of interbody fusion devices: fusion criteria for anterior lumbar interbody surgery.

The authors present their radiographic criteria for assessing fusion of the lumbar spine after anterior interbody fusion with intradiscal implants. These criteria include the assessment of plain radiographs, dynamic motion radiographs, and thin-cut computerized tomography scans. Fusion within the instrumented spinal motion segment can be determined using radiographic evaluation to assess spinal alignment on sequential examinations, angular and translational changes on dynamic motion studies, and device-host interface, and to identify new bone formation and bone remodeling. Finally, to aid the clinician in assessing fusion, the authors describe the five zones of fusion within the intervertebral disc space.