Paget’s disease of bone is a chronic disorder that interferes with the body’s normal recycling process in which the old bone tissue is replaced by new bone tissue. This is known as bone remodelling. Paget’s disease causes this recycling process to shift out of balance, resulting in the formation of abnormally shaped new bones which may be weak and brittle. It usually occurs in the spine, legs, skull and pelvis. The risk of Paget’s disease increases with age and also if any family members have this disorder. Paget’s disease can result in complications like broken bones, bone pain, arthritis, deformities, fractures, hearing loss and pinched nerves in the spine.
Causes of Paget’s disease
The exact cause of Paget’s disease is yet unknown. There are two cells that are responsible for bone remodelling: Osteoclasts which absorb the old bone and Osteoblasts which make the new bone. In Paget’s disease of bone, the osteoclast cells malfunction and absorb the old bone at a faster rate than usual. Because of this, the osteoblasts try to produce new bone at a faster rate, but the new bone is weaker than normal. However, doctors have identified certain risk factors which may make a person more susceptible to this disease.
They are:
- Genetics: In approximately one-third of the cases, Paget’s disease is inherited. Therefore, if a relative or a family member has this condition, a person is more likely to get affected.
- Age: The risk of Paget’s disease increases with an increase in age.
- Environmental Factors: There is evidence that the number of people with Paget’s disease is decreasing. This may indicate a possible role of environmental factors.
What are its symptoms?
Paget’s disease usually does not cause any symptoms. Many people are unaware that they have this disease until X-rays are taken for some other reason. However, when people are affected by this condition, the most common complaint is bone pain. The bone pain of Paget’s disease depends on the affected part of the body. In Paget’s disease, since the new bone is generated faster than normal, it is not as strong as the normal bone. This can result in increased risk and occurrence of fractures. Due to the bowing of the affected bones next to the joints, arthritis can also occur.
- Spine: When the spine is affected, the nerve roots can get compressed leading to pain, tingling and numbness in the limbs.
- Skull: An overgrowth of bone in the skull can cause headaches and/or hearing loss.
- Pelvis: If this disease occurs in the pelvic region, hip pain is a major symptom.
- Legs: In the legs, the new bones may undergo bending, causing a person to become bowlegged, and the extra stress on the adjacent joints can result in osteoarthritis in the knee or the hip.
In advanced stages of Paget’s disease, congestive heart failure may sometimes occur. If this disease occurs in several bones in the body, the osteoclasts which absorb the old bone may release sufficient quantities of bone causing an increase in calcium levels in the blood. This can lead to many other symptoms such as fatigue, weakness, abdominal pain, loss of appetite, constipation and many others.
How do doctors diagnose Paget’s disease of bone?
Most often, Paget’s disease is discovered when X-rays or blood tests are performed for some other reasons. If this condition is detected, doctors perform tests to confirm the diagnosis.
They are:
- X-rays: Paget’s disease can usually be detected by examining an x-ray. A bone affected by Paget’s disease appears larger and denser than a normal bone and may also appear deformed.
- Bone Scan: To determine which bones are affected by this disease, a small amount of radioactive dye is injected into a vein. A special camera then detects the areas of the skeleton where there is an increased absorption of the radioactive material. These indicate the regions where there is excess bone remodelling.
- Blood and Urine Tests: People who are affected by Paget’s disease usually have increased alkaline phosphatase levels due to high bone remodelling rate. Serum alkaline phosphatase tests and urine tests can help confirm the diagnosis.
- Biopsy: A small sample of the affected bone is extracted and examined in a lab to confirm the occurrence and assess the severity of the condition.
Treatment of Paget’s disease of bone
There is no specific treatment for this disease. Therefore, any treatment is aimed merely at relieving the symptoms and preventing future complications. Treatment measures are of two types: surgical and nonsurgical.
Nonsurgical treatments include:
- Bisphosphonate medication: These include a variety of medicines including alendronate (Fosamax), ibandronate (Boniva), pamidronate (Aredia), and risedronate (Actonel). All of these help control bone regeneration or remodelling.
- Nonsteroidal anti-inflammatory drugs (NSAIDs): Over-the-counter painkillers such as ibuprofen and paracetamol may be given to relieve the pain due to Paget’s disease or resultant conditions like arthritis.
- Supportive Therapies: Physiotherapy regimen and use of other devices such as braces, walking sticks or shoe inserts can help relieve pain by preventing misalignment of the affected bones.
In some cases, if further complications such as fractures, deformities or severe joint damage occur, surgery may be performed. Surgery can help heal the fractures, replace joints damaged by severe arthritis, realign deformed bones and reduce pressure on the nerves.
Some of the surgical procedures are:
- Osteotomy: In this process, the doctor removes a wedge of bone near the damaged joint in order to shift the weight onto a healthier part of the bone. This procedure can restore the alignment to the weight-bearing joints that are affected by Paget’s disease and help relieve the pain.
- Total joint replacement: The affected parts of the joint are removed and replaced with a metal or plastic device called the prosthesis. The prosthesis is designed to replicate the movement of a normal, healthy joint.
As with many of the diseases, some simple lifestyle habits and home remedies can help reduce the risk of Paget’s disease and its associated complications. Exercising regularly can help maintain the mobility of the joints and strengthen the bones, besides regulating a host of bodily processes. A healthy diet containing adequate levels of calcium and Vitamin D which helps in absorption of calcium can also be beneficial.
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