Diagnosis of Osteoporosis: Clinical and Densitometric Analysis

In women and men over the age of 50 and in postmenopausal women younger than age 50, osteoporosis can be diagnosed clinically on the basis of a fragility fracture irrespective of bone mineral density (BMD) values at any of the sites used for measurement. In the absence of a prior fragility fracture, osteoporosis can be diagnosed if the BMD T-scores are less then or equal to −2.5 in women and men age 50 and over and in postmenopausal women under the age of 50. ^1,2 For calculating T-scores in men and women, the normative database to be used is that derived from Caucasian women aged 20 to 29 years, a reference population derived from the US Third National Health and Nutrition Examination Survey. ² The 10-year future fracture risk is calculated based on Canadian Fracture Risk Assessment (FRAX) or Canadian Association of Radiologists and Osteoporosis Canada (CAROC) for postmenopausal women and men age 50 years and older. ²

In premenopausal women and men under the age of 50, a diagnosis of osteoporosis can be made clinically in the presence of fragility fractures. ³ Fracture risk is not appropriately quantified with FRAX under age 40 or CAROC under age 50. However, the presence of a vertebral or a “hip” fracture or multiple fragility fractures denotes a high fracture risk regardless of age. In the absence of prior fragility fractures, a diagnosis of osteoporosis cannot be made based on the BMD results only. A Z-score of −2 or lower is defined as “below the expected range for age” and a Z-score above −2.0 should be appropriately reported as “within the expected range for age.” ²

A fragility fracture has been defined as a fracture which occurs with a fall from standing height or less, except that hand, ankle, and foot fractures are, on the basis of evidence, not believed to be of osteoporotic provenance. ^1,2 Major osteoporotic fracture sites are proximal femur (“hip”), spine, forearm, and humerus. Other fracture sites including pelvis and rib fractures may also be classified as fragility if they occur with a fall from a standing height or less or minimal trauma. ²

Vertebral fractures on spinal radiographs have often been evaluated by the Genant semiquantitative technique. Recent research from Rotterdam, Hong Kong, and Canada suggests that vertebral fractures are best diagnosed on the basis of morphologic (qualitative) damage to vertebral end plates and/or cortices rather than morphometric tools relying on vertebral “measurements.” ⁴ In these studies, morphologic tools correlated best with bone mineral density, vertebral and nonvertebral fracture outcomes, and having better interobserver performance.