Paget’s disease of bone is a chronic disorder that typically results in enlarged and deformed bones in one or more regions of the skeleton. Excessive bone breakdown and formation cause the bone to be dense but fragile. As a result, bone pain, arthritis, noticeable deformities, and fractures can occur.
The cause of Paget’s disease is unknown. Recent studies, however, have suggested that the disease may be caused by a “slow viral” infection of bone, a condition that is present for many years before symptoms appear.
In addition, there is also a hereditary factor, since the disease may appear in more than one member of a family. The hereditary factor may lead to susceptibility among family members to the suspected viral infection.
Paget’s disease is most common in Caucasian people of European descent, but it also occurs in African-Americans. It is rare in those of Asian descent. Paget’s disease is rarely diagnosed in people under 40 but may occur in up to 3% of the American population over 60. Both men and women are affected.
Bone pain is the most common symptom. The pain may occur in any bone affected by Paget’s disease and often localizes to areas adjacent to the joints (e.g., hip pain may occur when the pelvis or thigh bone is involved). Headaches and hearing loss may occur when Paget’s disease affects the skull. Pressure on nerves may also occur when the skull or spine is affected. Deformities of bone, such as an increase in head size, bowing of a limb, or curvature of the spine, may occur in advanced cases. These deformities are due to enlargement or softening of the affected bones. Although Pagetic lesions may occur in multiple sites, it does not spread from bone to bone. When it is in the hip, however, damage to the cartilage of joints adjacent to the affected bone may lead to arthritis. Pagetic bone is susceptible to fractures with even moderate stress.
Bones affected with Paget’s disease have a characteristic appearance on x-rays. Sometimes, the patient’s doctor is alerted to the possibility of Paget’s disease when a blood test reveals an elevated level of alkaline phosphatase. In this case, more specific tests, such as the bone-specific alkaline phosphatase test, x-rays, and bone scans, are done. After the age of 40, siblings and children of someone with Paget’s disease may wish to have a standard alkaline phosphatase blood test every two or three years.
Hearing Loss in Paget’s Disease
When Paget’s disease affects the skull and the temporal bone (the bone that surrounds the inner ear), severe and progressive loss of hearing may occur. This may involve both sides or one side predominantly. If the loss of hearing is progressive and due to Paget’s disease, treating the underlying Paget’s disease may slow or stop the progression of the hearing loss. Hearing aids may sometimes be helpful.
Exercise is very important in maintaining skeletal health and is recommended for some patients with Paget’s disease. Before beginning any exercise program, it is wise to discuss the program with your physician, since undue stress on affected bones should be avoided. Exercise is also helpful in avoiding weight gain that may put additional stress on the bones and in maintaining the mobility of the joints.
Two classes of drugs are approved by the FDA for the treatment of this disease. Both classes of drugs suppress the abnormal bone remodeling that is associated with Paget’s disease:
- Bisphosphonates. Bisphosphonates are drugs that inhibit abnormal bone resorption. Three bisphosphonates are approved in the U.S. for treatment of Paget’s disease: Alendronate sodium (Fosamax®), which is given in tablet form; Etidronate disodium (Didronel®), which is also given in tablet form; and Pamidronate disodium (Aredia®), which is given intravenously.
- Calcitonin. Calcitonin is a hormone secreted by the thyroid gland that also inhibits abnormal bone resorption. Synthetic salmon calcitonin is taken by injection; the brand names for this drug are Calcimar®, Miacalcin®, and Osteocalcin®. At this time, Cibacalein® (synthetic human calcitonin), which is another drug approved by the FDA for treating Paget’s disease, can only be obtained if a physician requests it directly from the manufacturer. Talk to your physician about the treatment that is most appropriate for you.
There are generally three major complications of Paget’s disease for which surgery may be recommended. The first complication occurs when Pagetic bone fractures. Surgical fixation of Pagetic fractures may allow the fracture to heal in better position. The second complication occurs when the patient develops severe degenerative arthritis. If medication and physical therapy are no longer helpful, and if disability is severe, surgery may be considered as an option. Total joint replacement of the hips and knees should be reserved for the most severe cases of arthritis, when other methods of treatment are no longer effective. The third situation involves bone deformity, especially of the tibia. The surgical cutting and realignment of a Pagetic bone may help painful weight-bearing joints, especially the knees. Medical therapy prior to surgery is recommended to decrease bleeding during surgery and to prevent other complications during and after surgery.
Quality of Life
Some of the same issues that affect patients with osteoporosis and other chronic disorders affect patients with Paget’s disease. There has, however, been little research on the impact of Paget’s disease on quality of life. A study by Dr. Deborah Gold et al. that was published in the Journal of Bone and Mineral Research entitled “Paget’s Disease of Bone and Quality of Life” (vol. 11, no. 12, pp. 1897-1903) addressed the psychological,
social, and physical consequences of Paget’s disease as well as the impact they had on quality of life. This study was based on previous studies of patients with another prevalent chronic skeletal disorder — osteoporosis -because many of the physical consequences of these two disorders are similar.
Results of the study suggest that a substantial portion of the individual’s perception of quality of life depends on his or her physical condition and disease state. The greater the illness-related problems, the worse the quality of life. Income and education enhanced self-reported quality of life as did excellent self-rated health and health that had improved from 5 years previous. From this study, the researchers concluded that Paget’s disease of bone affects the psychological functioning of its sufferers considerably, and this finding may have an impact on treatment of Paget patients. If physicians and other health care professionals are aware of the likelihood of psychological issues, they may tailor treatment plans to include psychological outcomes, which may ultimately improve quality of life for patients with Paget’s disease of bone.
Specialists in Paget’s Disease
Endocrinologists (physicians that specialize in hormonal and metabolic disorders) and rheumatologists (physicians that specialize in joint and muscle disorders) are internists that are generally knowledgeable about treating Paget’s disease. Also, orthopedic surgeons, otolaryngologists (physicians that specialize in ear, nose, and throat disorders) and neurologists may be called upon to evaluate specialized symptoms in Paget’s disease.