A survey of bridging bone on chest radiography shows a greater than expected prevalence of marginal syndesmophytes.

Background: The recognition of thin marginal spinal syndesmophytes is important, in part due to their association with non-traumatic or mildly traumatic vertebral fractures.

Purpose: To determine a lower limit on the prevalence of marginal spinal syndesmophytes using chest radiographs.

Material and methods: We conducted a retrospective analysis of 500 chest radiographs, assessing the prevalence of thin marginal syndesmophytes, bridging or near-bridging osteophytes, and flowing paravertebral ossifications in the thoracic intervertebral discs among individuals aged 16 years and older in a North American city.

Results: Among the 500 participants, we observed that thin vertical marginal syndesmophytes were present in 17 (3.4%) cases, bridging or near-bridging osteophytes were present in 126 (25.2%) cases, and flowing paravertebral ossifications were present in 37 (7.4%) cases. Out of the 17 participants with thin marginal syndesmophytes, 10 exhibited a bamboo-like spine appearance, defined as the presence of ≥4 contiguous levels of bridging marginal syndesmophytes. Analysis of syndesmophyte distribution per vertebral level indicated a higher frequency of involvement in the mid to lower thoracic spine, maximal at T9/10.

Conclusions: The presence of thin marginal syndesmophytes in the thoracic spine on routine chest radiographs is substantially more prevalent than would be anticipated based on the existing literature. The feasibility of reliably identifying these syndesmophytes in the spine and the impact of this on morbidity should be further investigated due to their association with advanced ankylosing spondylitis and their susceptibility to fractures.