A comparison of new bone formation in patients with ankylosing spondylitis and patients with diffuse idiopathic skeletal hyperostosis: A retrospective cohort study over six years

Abstract

Objective. Ankylosing spondylitis (AS) and diffuse idiopathic skeletal hyperostosis (DISH) are both characterized by new bone formation in the spine but presumably have a different pathogenesis. This study was undertaken to compare the natural course of new bone formation in AS and DISH.Methods. Lateral radiographs of the cervical and lumbar spine from AS and DISH patients obtained at >2 time points within 6 years were analyzed to quantify osteophyte development. Radiographs were scored in a blinded manner by 2 readers using the modified Stoke AS Spine Score (mSASSS). Bone spurs were categorized as having an angle of <45°or >45°.Results. AS patients (n ‫؍‬ 146) were younger than DISH patients (n ‫؍‬ 141) (mean ؎ SD 54.2 ؎ 12.3 years versus 60.3 ؎ 7.7 years). Symptom duration (mean ؎ SD) was 23.6 ؎ 11.2 years in AS patients and 21.6 ؎ 12.4 years in DISH patients. The mSASSS at baseline was lower in DISH patients (mean ؎ SD 14.3 ؎ 6.7) than in AS patients (20.5 ؎ 14.5) but had increased by a similar amount at followup (3.3 ؎ 4.2 versus 4.1 ؎ 9.5). The mean mSASSS progression rate per year (1.3 units) was also comparable. The mean ؎ SD number of syndesmophytes per patient was higher in AS (5.7 ؎ 5.5) than DISH (2.7 ؎ 2.8) patients (P < 0.001), while degenerative bone spurs (mean ؎ SD) were more frequent in DISH (1.4 ؎ 1.8) than AS (1.0 ؎ 1.4) patients. AS patients developed more new bone spurs with an angle of <45°than >45°per patient (mean ؎ SD 2.1 ؎ 2.7 versus 0.6 ؎ 0.9) (P < 0.001), while similar amounts of both types of bone formation were seen in DISH patients. Diffuse idiopathic skeletal hyperostosis (DISH) and ankylosing spondylitis (AS) are the 2 most common diseases that are characterized by ossification of the ligaments and tendons in both the axial skeleton and peripheral sites (1-3). Formation of new bone in the spine is most typically seen at the anterior site of the vertebrae, but it does also occur at other sites in both diseases (4,5). The lower part of the thoracic spine and the upper part of the lumbar spine are the most frequently involved regions in both conditions (6-8). Osteophytes, commonly referred to as bone spurs, are bony projections that form along joint margins (9). Conclusion. Our findings indicate that the rates of new bone formation in AS andThe radiographic appearance of both diseases is very similar, but the underlying pathology differs. Although there is no doubt that both spinal inflammation and new bone formation occur in AS, exactly how they are related is not so clear (10). Even less is known about DISH in this regard. While immune-mediated inflammatory rheumatic processes largely based on a genetic background are believed to occur in AS (11), DISH is

Diffuse idiopathic skeletal hyperostosis (DISH): where we are now and where to go next

“…[37][38][39] These modalities are also helpful in the evaluation of peripheral enthesopathy for which US is also a readily available and sensitive tool. 40 A small case-control study suggested that MRI was capable to detect vertebral corner fat infiltration similar to findings in AS.…”

Impaired quality of life in adults with X-linked hypophosphatemia and skeletal symptoms

“…In ax-SpA, there is some evidence that inflammation precedes radiographic progression in the skeleton (36,37) or that new bone formation can be considered as a repair mechanism associated with the transformation of new inflammatory lesions to fatty degenerative changes (38,39). However, formation of enthesophytes can occur in absence of inflammation and may be due to excess of mechanical stress and composition of the bone matrix.…”

Spondyloarthritis and Diffuse Idiopathic Skeletal Hyperostosis: Two Different Diseases That Continue to Intersect

“…Establishing the presence of DISH in patients with SpA can be useful in better evaluating the damage to the musculoskeletal system and the cardiovascular risk. It is desirable that interest in DISH continue to expand because an understanding of the mechanisms involved in the bone proliferation of DISH could also elucidate the relationships between inflammation and bone proliferation in axial and peripheral SpA 21 .…”