Kyphosis does not equal vertebral fractures: the Rancho Bernardo study.J Rheumatol. 2004 Apr; 31(4):747-52.JR
Kyphosis is considered a clinical sign of osteoporotic vertebral fractures. We examined the association of radiographically defined kyphosis with vertebral fractures to determine if this belief was true.
A total of 1407 ambulatory white adults, aged 50-96 years, from the middle-class community of Rancho Bernardo, California, USA, attended a 1992-96 research clinic visit. Bone mineral density (BMD) was measured at the hip and spine, and lateral thoracolumbar spine radiographs were obtained. The degree of kyphosis was determined using the modified Cobb method.
A total of 114 of 553 men (20.6%) and 188 of 854 women (22.0%) had one or more thoracic vertebral fractures. Degenerative disc disease was observed in 45.4% of men and 56.7% of women. The mean age-adjusted Cobb angle was significantly higher (p < 0.001) in men and women with vertebral fractures in comparison to those without vertebral fractures: men 51.3 degrees vs 41.5 degrees, respectively, and women 56.4 degrees vs 46.3 degrees. The prevalence of vertebral fracture increased with higher Cobb angles and there was no significant difference by sex. The proportion of women with osteoporosis increased with the increase of Cobb angle. In the upper quartile of the Cobb angle distribution (> or = 55.5 degrees), only 36.2% of men and 36.9% of women had prevalent thoracic vertebral fractures; and osteoporosis using WHO BMD criteria was present at the total hip in 9.7% of men and 32.7% of women.
The majority of men and women with exaggerated kyphosis (the upper quartile of the Cobb angle) had no evidence of thoracic vertebral fractures or osteoporosis. Degenerative disc disease, not vertebral fractures, was the most common finding associated with radiographically defined angle of kyphosis in men and women. Thus kyphosis per se should not be considered diagnostic of osteoporosis. Nevertheless, patients with exaggerated kyphosis should be evaluated for underlying osteoporotic fracture.