Paget's disease fracture. Coloured X-ray showing a fractured clavicle (collar bone) at the shoulder, caused by Paget's disease. The fracture is visible as a clear break at top centre in the light blue region of the horizontal bone running across the top. The upper arm bone is at right (green). Paget's disease (medical name: osteitis deformans) is a chronic bone disease which occurs in the elderly. Affected bones thicken, their structure becomes disorganized, and they weaken with an increased tendency to fracture.