Patient description: The patient is a 53-year-old man complaining of frequent headaches, generalized bone pain and difficulty chewing that started 6 years ago and is getting worse. Examination shows bilateral swellings around the molars. The swellings have increased since his last examination. Several extraoral lesions of the head and face are detected. The swellings are non-tender and attached to the underlying bone. Further evaluation shows increased uptake of radioactive substance as well as an increase in urinary pyridinoline. The serum alkaline phosphatase is 300 IU/L (the normal range is 44- 147 IU/L). The patient's sister had the same problems. She was diagnosed with Paget's disease of bone when she was 52 years old. The diagnosis of Paget's Disease of Bone is confirmed and Bisphosphonate will be started as first-line therapy.

Clinical trial eligibility criteria: eligible ages (years): 50.0-999.0,  Osteoporosis Bone Diseases, Metabolic Hip Fractures STUDY GROUP For the respective groups, individuals need to be either: 1. Diagnosis of Osteoporosis or Osteopenia AND have received bisphosphonate therapy for at least 5 years 2. Diagnosis of Osteoporosis or Osteopenia AND have received bisphosphonate therapy for less than 1 year 3. Diagnosis of Osteoporosis or Osteopenia AND have received bisphosphonate therapy for 1 to 5 years 4. No Diagnosis of Osteoporosis or Osteopenia AND have never received bisphosphonate therapy In Common Will Be: 1. Age 50 or older 2. Ambulatory 3. Living independently  STUDY GROUP Will Be: 1. Inability to provide informed consent 2. Cognitive Impairment (MCI/dementia) 3. Current diagnosis of cancer including: breast, prostate, lung, colon, stomach, bladder, uterus, rectum, thyroid, and kidney 4. Previous bilateral hip fractures 5. Pregnancy 6. Small bowel resections 7. Malabsorption 8. Paget s Disease of the Bone 9. Preexisting osteomalacia, active malignancy, prior bone metastasis, osteogenesis imperfecta, fibrous dysplasia, history of kidney failure STUDY GROUP: For the respective groups, individuals need to be either: 1. Diagnosis of atypical femur fracture within the past 10 years, regardless of bisphosphonate use. OR 2. Diagnosis of Osteoporosis or Osteopenia AND have received bisphosphonate therapy for at least 5 years without atypical femur fracture In Common Will Be: 1. Age 45 or older 2. Ambulatory 3. Living independently STUDY GROUP will be: 1. Inability to provide informed consent 2. Cognitive Impairment (MCI/dementia) 3. Current diagnosis of cancer including: breast, prostate, lung, colon, stomach, bladder, uterus, rectum, thyroid, and kidney 4. Pregnancy 5. Small bowel resections 6. Malabsorption 7. Paget s Disease of the Bone The following information pertains to individuals in the Longitudinal Group. Individuals who currently have thigh pain will not be excluded from this study. As the goal of this study is to correlate medication usage with a radiographic feature, individuals concurrently with thigh pain will still be considered, but we will take note of the duration of medication usage and the start of thigh pain per participant history. Duration of thigh pain prior to fracture will likewise be considered. If a current fracture is found on radiographs or suspicion is high for a fracture, selected participants will be sent for MRI of bilateral femurs and participant will be referred back to their primary provider for additional evaluation and treatment. Individuals who have previously had a unilateral hip fracture or arthroplasty will also not be excluded. As several previous studies have shown, bilateral fractures are not uncommon. We will continue to monitor the progress on the contralateral hip. We will query for details regarding history of first fracture and medication usage. These participants will be subanalyzed for medication usage and time between fractures. Individuals with bilateral (but not unilateral) fractures and bilateral arthroplasty initially will be excluded. However, individuals who are found to have unilateral or bilateral fractures during radiographic studies or undergo unilateral or bilateral arthroplasty during their three years of participation will be allowed to remain in the protocol, and we will assess for change in their anatomy. Individuals who are being treated with corticosteroids or other types of medications will not be excluded from this study. These variables will be considered confounders and will be analyzed by univariate analysis. Individuals with anatomical variations such as coxa vara or coxa valga will not be excluded. We will assume that they will be equally distributed into control and treatment groups. These individuals may be at higher risk for atypical fractures, and will be subanalyzed with appropriate femoral-angle matched controls. Controls that choose to begin bisphosphonate during the study will not be excluded from the study, but will be included in a subanalysis of individuals with less than 3 years of bisphosphonate exposure. Likewise, participants who choose to discontinue bisphosphonate usage will also not be dropped from the study. Analysis will be carried through with groups designated by intent to treat. Users who have taken the drug for 5 years and more who are currently on a drug holiday are eligible (because the drug stays in the bone for so long)