[Appropriateness and limitations of bone mineral measurements by DXA (dual energy x-ray absorptiometry) in the elderly--comparison with x-ray findings]

Area of Science:

• Gerontology
• Radiology
• Orthopedics

Background:

• Osteoporosis is a significant health concern in the elderly.
• Accurate bone mineral density (BMD) assessment is crucial for diagnosing and managing osteoporosis.
• Aging-related calcifications can interfere with BMD measurements, particularly in the lumbar spine.

Purpose of the Study:

• To evaluate the appropriateness and limitations of dual energy x-ray absorptiometry (DXA) for measuring bone mineral density (BMD) in elderly individuals.
• To investigate the influence of aging-related calcifications (spinal osteophytosis, abdominal aortic calcification) on lumbar spine and proximal femur BMD measurements.
• To determine the most reliable skeletal sites for BMD assessment in the elderly population.

Main Methods:

• Bone mineral density (BMD) measurements were performed using dual energy x-ray absorptiometry (DXA) on 674 elderly individuals.
• Measurements included the lumbar spine (anteroposterior projection) and three proximal femur regions (femoral neck, trochanter, Ward's triangle).
• Correlation analyses were conducted to assess the association between BMD values and the presence/severity of spinal osteophytosis and abdominal aortic calcification.

Main Results:

• DXA measurements were less feasible in older, less competent, or more symptomatic individuals.
• Lumbar spine BMD (AP projection) did not show typical age-related declines and was strongly correlated with spinal osteophytosis and aortic calcification.
• Proximal femur BMD measurements demonstrated linear age-related declines and showed no significant association with these abnormal calcifications.

Conclusions:

• Lumbar spine BMD measurements using DXA in the elderly can be significantly influenced by co-existing calcifications, potentially leading to inaccurate assessments.
• Proximal femur BMD measurements are more reliable indicators of bone mineral density in the elderly, unaffected by spinal and aortic calcifications.
• For accurate bone health evaluation in older adults, focusing on proximal femur BMD is recommended over lumbar spine BMD when confounding calcifications are present.