Several factors influence deformities in healthy vertebrae
MedWire News: Prevalent vertebral fractures, hyperkyphosis, low bone mineral density (BMD), and advancing age all influence the level of wedging deformity in nonfractured vertebrae, Argentinean researchers report.
The presence of these factors "could contribute to a higher vulnerability of the vertebrae, making them more susceptible to fractures," remark Ariel Sánchez (Centro de Endocrinología de Rosario) and colleagues.
"Vertebral deformities are associated with higher morbidity, mortality, and financial burden for health services," say the researchers who investigated the vulnerability of healthy vertebrae in 175 postmenopausal women with and without vertebral compression fractures.
The women, who had a mean age of 69.7 years, had not received any prior treatment for osteoporosis.
Anteroposterior and lateral radiographs of the thoracic spine revealed that 45 of the women had evidence of prevalent vertebral fracture, while the remaining 130 had experienced no fractures.
Using bone morphometry, the researchers measured the wedging angle and degree of kyphosis (as determined by the Cobb angle) of each vertebral body. They then calculated the mean wedge angle (MWA) of the nonfractured (healthy) vertebrae, which was considered an indicator of the structural vulnerability of nonfractured vertebrae.
Patients with prevalent fractures had significantly lower BMD (0.699 vs 0.774 g/cm2), wider Cobb angle (64.5 vs 44.3°), and a higher sum of wedge angles (48.3 vs 27.3°) and MWA of healthy vertebrae (4.1 vs 3.0°) than patients without vertebral fractures.
In addition, women with vertebral fractures had significantly greater height loss than women without such fractures, at 7.1 versus 3.6 cm.
Multivariate analysis showed that increasing MWA of healthy vertebrae was independently associated with advancing age, lower femoral neck BMD, presence of clinical kyphosis, and vertebral fractures.
Furthermore, healthy vertebrae from patients with prevalent fractures had a MWA that was 15% higher than that in patients without fractures, which could indicate that the healthy vertebrae in fracture patients have greater structural vulnerability than those in patients without fractures, Sánchez and co-authors remark.
Writing in the journal Bone, the researchers conclude that their findings "suggest that nonfractured, mildly deformed vertebrae present a structural morphometric deterioration that increases with age."
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By Laura Dean