Bone densitometry is the measurement of the density of the bone. Currently, this is performed at either the screening level or the diagnostic level.
Screening bone densitometry generally consists of an ultrasound or low energy Xray analysis. The calcaneus (heel bone) is the most commonly screened bone, being the most dense in the body, but the distal radius and other bones may also be used.
The diagnostic test is a more comprehensive, sensitive, and specific test. It consists of radial tomography images of the proximal femur and lumbar spine. This generally follows a screening test that shows an abnormal result.
The results of the ultrasound or Xray are compared with average standardized scores based on a twenty-five year old individual of the same sex. This results in a score for the patient, with 0.0 being identical to baseline. The more negative the score, the lower the bone density is. Generall under -1.0 to -1.5, a patient is considered osteopenic. Under -2.0 to -2.5, a patient is considered to have osteoporosis.
As society ages due to advances in health care and medical technology, osteoporosis becomes a growing problem. The incidence of hip fractures rises with age, and the average life expectancy after a fracture of the hip is only two years. The morbidity and mortality related to osteoporosis and its cost to society as a whole is astounding!
Bone densitometry as a screening tool will become increasingly important if current societal trends continue.