High prevalence of thoracic vertebral deformities and discal wedging in ankylosing spondylitis patients with hyperkyphosis.
OBJECTIVE
To study the prevalence of deformities of vertebrae and intervertebral discs in patients with ankylosing spondylitis (AS) in relation to fixed hyperkyphosis of the spine.


METHODS
Altogether 50 patients (15 women, 35 men) with AS were studied. Hyperkyphosis was measured by the occiput to wall distance (OWD). Anterior (Ha), mid- (Hm), and posterior height (Hp) of the vertebrae and intervertebral discs were measured on lateral radiographs of the thoracic (Th5-Th12) and lumbar spine (L1-L5). Vertebral shapes were analyzed according to McCloskey, et al. Wedging of discs was calculated as Ha/Hp. Hyperkyphosis was defined as OWD > 1 cm.


RESULTS
In the thoracic spine, the prevalence of vertebral deformities was higher in patients with hyperkyphosis (n = 38) compared to patients without hyperkyphosis (n = 12) (45% vs 8%; p = 0.01). The prevalence of thoracic vertebral deformities in patients with hyperkyphosis differed little between men and women (39% vs 58%; p > 0.10) and among patients above and below the age of 45 years (50% vs 33%; p > 0.10). Patients with one or more deformed thoracic vertebrae had a higher mean OWD than patients without deformed vertebrae (12 +/- 7 vs 7 +/- 6 cm; p < 0.01). The total sum of deformities of the thoracic vertebrae and discs explained 43% of the variance of the age adjusted OWD (p < 0.001). Deformities of lumbar vertebrae and discs did not contribute to hyperkyphosis.


CONCLUSIONS
In patients with AS and hyperkyphosis, deformities of the thoracic vertebrae occur frequently and, together with wedging of the thoracic discs, contribute significantly to fixed hyperkyphosis of the spine.
Geusens
P
P
Department of Rheumatology, University Hospital, University of Maastricht, The Netherlands. piet.geusens@ping.be
Vosse
D
D
van der Heijde
D
D
Vanhoof
J
J
van Tubergen
A
A
Raus
J
J
van der Linden
S
S
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D006801:Humans; D004057:Hyperostosis, Diffuse Idiopathic Skeletal / Q000453:epidemiology* / Q000473:pathology; D007403:Intervertebral Disc / Q000473:pathology*; D007738:Kyphosis / Q000453:epidemiology* / Q000473:pathology; D008159:Lumbar Vertebrae / Q000473:pathology; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000453:epidemiology / Q000473:pathology; D015995:Prevalence; D012044:Regression Analysis; D013904:Thoracic Vertebrae / Q000473:pathology*