Bisphosphonate Users Radiographic Characteristics of the Hip (BURCH) Study

Objective: Bisphosphonates are a class of medications that treat osteoporosis and prevent fractures, and have been available for more than a decade. However, there have been recent studies that have shown that, on rare occasions, they may be associated with an atypical hip fracture after long-term use. Radiographic features such as beaking and thickening along the side of the hip bone have been frequently observed with these atypical femur fractures, but most of the studies to date have only been focused on finding the fractures, not the x-ray features. It is not known how common these x-ray features and pain symptoms are amongst bisphosphonate users that have not yet experienced a fracture. If there is a difference between users and non-users, these features may be a valuable finding to help catch fractures before they happen. A recent hypothesis has emerged that a genetic condition, hypophosphatasia, may play a role. Study population: This study will evaluate the presence of these features in users of bisphosphonates and the general population. Individuals from the community who have taken bisphosphonates for five or more years (and still taking or have since stopped) will be compared with individuals recently starting bisphosphonate treatment and individuals without osteoporosis and not taking bisphosphonates but similar in age. Another cohort of patients who have sustained atypical femur fractures will also be recruited. Design: This study will be look at the frequency of subtrochanteric beaking and cortical thickening between three groups of people: long-term users, short-term users, and non-users. Thorough medication usage history, physical examination of the hip and radiographs (x-rays) will be taken three times over the course of three years, and a one time bone density scan will be performed upon enrolling. We will also perform genetic testing for hypophosphatasia in long term asymptomatic users and patients who have sustained the atypical femur fracture. Outcome measures: We will be looking for the presence of these "beaks" and measuring the thickness of the hip bone at a certain spot. We are interested in seeing if there is a difference between our three groups of people at first and also if these two features change over three years. We will also monitor for thigh pain, a feature of impending fracture, and if any fractures are found on x-rays. We will compare the prevalence of hypophosphatasia mutations in asymptomatic bisphosphonate users and subjects who have sustained the atypical femur fracture.