Frequency of Vertebral Compression Fractures in Spinal Osteoarthritis Patients in Relation to Bone Mineral Density

Park, Jun Sup; Joo, Yeong Shil; Choi, Yun Sun; Cheong, Myeong A; Ha, Hyung Keun; Jung, In Su; Kim, Si Min; Kim, Byoung Joon; Ahn, Kyu Jeong; Choi, Young Kil

Abstract

OBJECTIVE
To investigate the association between bone mineral density (BMD) and osteoporotic compression fractures in radiographic spinal osteoarthritis (OA) patients.
METHODS
Subjects were 382 female patients (ages 45 to 85) from outpatient clinic for osteoporosis and rheumatic diseases. BMD was measured at lumbar spine and hip by dual X-ray absorptiometry (Hologic QDR 2000). The standard anteroposterior and lateral plain radiographs of thoracic and lumbar spine were taken to define spinal OA and vertebral compression fractures. Radiographic spinal OA was defined by grade of disc degeneration and facet joint degeneration. Frequency of vertebral fractures was compared between spinal OA and control patients in relation to their BMD, age, weight, body mass index (BMI) and years post menopause.
RESULTS
Higher proportion of fracture cases were observed in spinal OA patients than non-spinal OA patients (34.1%, 44/129 vs. 18.2%, 46/253, p<0.001) despite comparable mean BMD (0.836+/-0.152 vs. 0.834+/-0.185, p=0.89) and older mean age (65.8+/-8.5 vs. 57.8+/-10.3, p<0.001). In subjects of ages from 65 to 74, spinal OA patients showed significantly higher BMD than non-spinal OA patients (0.784+/-0.125 vs. 0.719+/-0.119, p=0.007), but the frequency of fractures seems to be higher than that of non-spinal OA patients (44.9%, 22/50 patients vs. 34%,19/55 patients, p=0.58). When all study subjects were stratified according to their spine BMD (normal, osteopenia, and osteoporosis), significantly higher proportion of vertebral compression fractures was noted in spinal OA than non-spinal OA patients in osteopenia group (38.5% vs. 13.5%, p<0.001).
CONCLUSION
Higher BMD does not seem to be translated directly into decreased risk of osteoporotic compression fractures in spinal OA patients. Careful assessment of risk factors for osteoporotic fractures and newer methods for assessing bone strength in this group of patients are needed.