RISK ASSESSMENT OF FRACTURES DURING BIPHOSPHATE TX BY ULTRASOUND WITH BQ1-H2

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Osteoporosis is a major medical problem, clinically manifested by skeletal fractures occuring with minimum trauma (henceforth named atraumatic fractures). Because bone density is inversely correlated with the rate of skeletal fractures, bone density has been used to define osteoporosis, with a value below about 75% of normal peak value (T-score<-2.5) referred to as osteoporosis even in the absence of fractures. However, bone density alone does not predict the risk of fractures. Some patients with normal bone density develop non-traumatic fractures, and some with low bone density do not sustain fractures. One explanation for this finding is that bone "quality" may sometimes be "out of step" from bone density. Thus, some subjects with low bone density may be less susceptible to fracture, if bone quality is superior. On the other hand, some with high bone density may be susceptible to fractures if bone quality is poor. There are some conditions that are associated with or cause deterioration of bone quality, such as Paget's disease of bone, osteomalacia or rickets, immobilization, and endemic fluorosis. Bone quality is defined as the "totality of features and characteristics that influence a bone's ability to resist fractures" (bone strength). Unfortunately, there is no commercial device that can measure bone quality non-invasively. Bone strength can only be measured directly by mechanical testing. However, such methods cannot be applied clinically because of their destructive and invasive nature. It has previously been shown that modulus of elasticity (the parameter that decribes the relationship between stress and strain) correlates with and can be used as a predictor of bone strength. This is the basis for using ultrasound velocity (or its function) as a non-invasive approach of assessing bone strength. However, the available methods are based on the transmision ultrasound, wherein the time or speed of ultrasound traversing across bone tissue is measured. Unfortunately, the data obtained therein are influenced by bone geometry and density at the organ level, overlying tissue and bone marrow content, and can thus only partly reveal bone quality. The purpose of this study is to assess the risk of developing atraumatic fractures in postmenopasal women taking therapeutic bisphosphonate (BP) for osteoporosis/osteopenia by ultrasound critical angle reflectometry (UCR). The UCR device performs a measurement of normalized elasticity of bone which can be used as an aid to the physician in gauging risk for developing atraumatic fractures during bisphosphonate treatment.