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): 18.0-999.0,  Painful Joint Prostheses Patients selected for entry into this study will be men or women of any ethnic background who are scheduled to undergo clinical and diagnostic evaluation by a member of the Department of Orthopedic Surgery at the Hospital of the University of Pennsylvania Health System or by the collaborating physicians at the Rothman Institute or the VA Philadelphia Medical Center. Study I: FDG-PET imaging in painful partial or total joint prostheses Each patient who is a candidate will be evaluated by one of the collaborators mentioned above for a painful partial or total joint prosthesis. The patient will undergo an appropriate routine evaluation including history, physical examination, radiographic, scintigraphic, and necessary laboratory evaluation. An initial diagnosis must be made for each patient. The diagnosis of loosening will be established based on clinical examination and/or radiographic evaluation demonstrating clear evidence of this complication. Other etiologies for the joint pain, except for infection and aseptic loosening, need to be excluded. Surgical intervention (prosthesis revision) may or may not be planned for the patient who is a candidate for this study. Study II: FDG-PET imaging following uncomplicated partial or total joint arthroplasty All patients fulfilling the below will be considered potential candidates for this study. Each patient must have a diagnosis of degenerative joint disease caused by osteoarthritis (no previous hip surgery) and have undergone primary partial or total joint arthroplasty by a member of the Department of Orthopedic Surgery at the Hospital of the University of Pennsylvania or referring hospitals. Other causes of degenerative joint disease will be excluded by physical, radiographic and laboratory evaluation as clinically indicated. Osteoarthritis is the most common cause of degenerative joint disease, and in order to avoid any confounding factors in experimental results that may be caused by other types of disorders, only this group of patients will be studied. A patient will be eliminated from this group at anytime if the post-operative course is complicated by any process that is thought to influence the outcome. Variations from an uncomplicated postoperative course will be determined by the operating surgeon and clinical signs or other evidence to suggest infection, early loosening, or any other process directly involving the prosthesis  Patients with other etiologies for pain, other than for infection and aseptic loosening, will be excluded from enrollment into the study