[Bone densitometry and ultrasound studies of the bone: methods, indications and efficacy].

The amount of calcium-containing crystals in bone tissue can be determined by osteodensitometry. The most common methods use X-ray energy. Two-dimensional approaches (dual-energy X-ray absorptiometry, DXA) have to be distinguished from volumetric measurements (quantitative computed tomography, QCT). Using ultrasound, broadband ultrasound attenuation (BUA) and ultrasound transmission velocity (SOS) can be measured. The results measured are correlated to fracture risk. Thus, considering the criteria of evidence-based medicine, these measurements are suitable for estimating the individual risk for osteoporotic fractures. Measurements can be recommended to persons with evidence for an increased osteoporosis risk based on the patient's clinical data and family history. According to a recommendation of a WHO working group in 1994, definition of osteoporosis can be based on osteodensitometry, which has now been widely accepted. Nowadays, we are able to evaluate the usefulness of osteodensitometry using X-ray energy for patient follow-up and treatment monitoring. However, not enough data are available with regard to ultrasound measurements. The correct use of these methods implies the observance of and attention to quality standards as defined by a working group of the Osteology Association ("Dachverband Osteologie" in the German-speaking countries).