Osteoporosis has received much attention as a bone disease of the elderly. Very few people are as familiar with Paget’s disease of the bone yet it is the second most common bone disease in the elderly after osteoporosis. Paget’s disease of the bone is more common in males than females and affects about 1% of Americans over the age of 40 years. The prevalence increases with age and about 1 in 10 people over the age of 80 have Paget’s disease. Overall, however, the condition seems to be decreasing in prevalence. It is a condition that not only affects the bones but has a host of effects on other organs of the body, including the heart and nerves.
Paget’s disease of bone is a chronic bone disorder affecting the adult skeleton where the bone matrix is irregular. Bone is constantly undergoing remodeling but it is an orderly process ensuring that the strength and structure of the bone is not compromised. In Paget’s disease the cells responsible for resorbing bone, osteoclasts, are more active at some points. The cells that lay down new bone, osteoblasts, are also more active at certain points. Therefore parts of the bone are less compact while other parts are overgrown. Ultimately though the bone is structurally weaker.
The exact cause of Paget’s disease has not been conclusively identified. Although genetic abnormalities have been isolated in people with Paget’s disease, the exact mechanism by which it affects normal bone remodeling is not known. There is also some evidence to suggest that a prior viral infection may play some role in Paget’s disease. However, Paget’s disease is not an infectious disorder. It is thought that some genetically susceptible people are more likely to be at risk of Paget’s disease through a viral component.
Weakening of the bones causes it to bend and become deformed over time as it is unable to bear the body weight. It causes pain in the bones and also on the joints as the misshapen bones can place additional strain on the joints. This can progress to conditions such as osteoarthritis. Many of the other more serious symptoms is a result of bone overgrowth. A protrusion of the bone presses on the surrounding tissue around the bone. This contributes to a host of other signs and symptoms. An outgrowth from the skull causes headaches and hearing loss. Bone protrusions of the vertebrae (spine) presses against nerve roots causing pain, tingling and numbness of the limbs
The same osteoporosis drugs can be used to treat Paget’s disease. Bisphosphonates are the most popular drug of choice. Certain hormones that control calcium levels, like calcitonin, influences bone growth and development. Therefore it can influence bone metabolism. Surgery may be necessary in rare cases to correct fractures, straighten deformed bones and for joint replacement. Regular monitoring of the bone is necessary to monitor the progression of the disease and effectiveness of the medication. It is also useful to identify the early stages of other disease like bone cancer which may arise in Paget’s disease.