Disease-specific definitions of new bone formation on spine radiographs: a systematic literature review

We aimed to explore the radiographic definitions of types of New Bone formation (NBF) by focusing on the terminology, description and location of the findings.

Three systematic literature reviews were conducted in parallel to identify the radiographic spinal NBF definitions for spondyloarthritis (SpA), Diffuse Idiopathic Skeletal Hyperostosis (DISH) and Osteorathritis (OA). Study characteristics and definitions were extracted independently by two reviewers. Definitions were analysed and collated based on whether they were unique, modified or established from previous research.

We identified 33 studies that indicated a definition for the NBF in SpA, 10 for DISH and 7 for spinal OA. In SpA, the variations in syndesmophytes included the description as well as the subtypes and locations. The differentiation of syndesmophytes from osteophytes were included in 12 articles, based on the origin and the angle of the NBF and associated findings. The definitions of DISH varied in the number of vertebrae, level and laterality. For OA, five articles indicated that osteophytes arose from the anterior or lateral aspects of the vertebral bodies, and two studies required a size cut-off.

Our ultimate aim is to create formal NBF definitions for SpA, DISH and OA guided by an atlas, through a Delphi exercise with international experts. The improved ability to differentiate these conditions radiographically will not only allow the clinicians to accurately approach patients but also will help the researchers to better classify patient phenotypes and focus on accurate radiographic outcomes.