The assessment of fracture risk

Abstract

Bone mineral density is considered to be the standard measure for the diagnosis of osteoporosis and the assessment of fracture risk. The majority of fragility fractures occur in patients with bone mineral density in the osteopenic range. The Fracture Risk Assessment Tool (FRAX) can be used as an assessment modality for the prediction of fractures on the basis of clinical risk factors, with or without the use of femoral neck bone mineral density. Treatment of osteoporosis should be considered for patients with low bone mineral density (a T-score of between -1.0 and -2.5) as well as a ten-year risk of hip fracture of > or = 3% or a ten-year risk of a major osteoporosis-related fracture of > or = 20% as assessed with the FRAX. Biochemical bone markers are useful for monitoring the efficacy of antiresorptive or anabolic therapy and may aid in identifying patients who have a high risk of fracture. An approach combining the assessment of bone mineral density, clinical risk factors for fracture with use of the FRAX, and bone turnover markers will improve the prediction of fracture risk and enhance the evaluation of patients with osteoporosis.

Fig. 1

The effects of several clinical risk factors on the ten-year probability of a major osteoporotic fracture occurring in sixty-five-year-old white men and women from the United States. (Reprinted from: Kanis JA, Oden A, Johansson H, Borgström F, Ström O, McCloskey E. FRAX^® and its applications to clinical practice. Bone. 2009;44:734-43, with permission from Elsevier.)

Fig. 2

Image of FRAX^® web page (http://www.shef.ac.uk/FRAX) showing the chart for input of data and format of results in the United States version of the FRAX^® tool. (Printed with permission of the World Health Organization Collaborating Centre for Metabolic Bone Diseases, University of Sheffield. FRAX^® is registered to Professor J.A. Kanis, University of Sheffield.)

Fig. 3

Both NTX and CTX are reliable markers of bone resorption. During osteoclast-mediated resorption of bone, the collagen molecule is degraded, producing an aminoterminal (or N)-telopeptide, a carboxyterminal (or C)-telopeptide, and a central region of intact triple helix. Cross-linked N-telopeptides and C-telopeptides, known as NTX and CTX, respectively, are specific for bone and achieve a measurable concentration in blood and urine.