Inflammatory lesions of the spine on magnetic resonance imaging predict the development of new syndesmophytes in ankylosing spondylitis: evidence of a relationship between inflammation and new bone formation.
OBJECTIVE
To determine whether a vertebral corner that demonstrates an active corner inflammatory lesion (CIL) on magnetic resonance imaging (MRI) in patients with ankylosing spondylitis (AS) is more likely to evolve into a de novo syndesmophyte visible on plain radiography than is a vertebral corner that demonstrates no active inflammation on MRI.


METHODS
MRI scans and plain radiographs were obtained for 29 patients recruited into randomized placebo-controlled trials of anti-tumor necrosis factor alpha (anti-TNFalpha) therapy. MRI was conducted at baseline, 12 or 24 weeks (n=29), and 2 years (n=22), while radiography was conducted at baseline and 2 years. A persistent CIL was defined as a CIL that was found on all available scans. A resolved CIL was defined as having completely disappeared on either the second or third scan. A validation cohort consisted of 41 AS patients followed up prospectively. Anonymized MRIs were assessed independently by 3 readers who were blinded with regard to radiographic findings.


RESULTS
New syndesmophytes developed significantly more frequently in vertebral corners with inflammation (20%) than in those without inflammation (5.1%) seen on baseline MRI (P<or=0.008 for all reader pairs). They also developed more frequently in vertebral corners where inflammation had resolved than in those where inflammation persisted after anti-TNF treatment. This was confirmed in the analysis of the prospective cohort, in which significantly more vertebral corners with inflammation (14.3%) compared with those without inflammation (2.9%) seen on baseline MRI developed new syndesmophytes (P<or=0.003 for all reader pairs).


CONCLUSIONS
Our findings indicate that a syndesmophyte is more likely to develop from a prior inflammatory lesion, supporting a relationship between inflammation and ankylosis.
Maksymowych
Walter P
WP
University of Alberta, Department of Medicine, Edmonton, Alberta, Canada. walter.maksymowych@ualberta.ca
Chiowchanwisawakit
Praveena
P
Clare
Tracey
T
Pedersen
Susanne J
SJ
Østergaard
Mikkel
M
Lambert
Robert G W
RG
D000328:Adult; D000911:Antibodies, Monoclonal / Q000627:therapeutic use; D018501:Antirheumatic Agents / Q000627:therapeutic use; D002574:Cervical Vertebrae / Q000276:immunology / Q000473:pathology*; D005260:Female; D006801:Humans; D000069285:Infliximab; D008159:Lumbar Vertebrae / Q000276:immunology / Q000473:pathology*; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D010000:Osteitis / Q000276:immunology / Q000473:pathology*; D010012:Osteogenesis / Q000276:immunology*; D013167:Spondylitis, Ankylosing / Q000188:drug therapy / Q000276:immunology / Q000473:pathology*
D000911:Antibodies, Monoclonal; D018501:Antirheumatic Agents; D000069285:Infliximab