What is Paget Bone Disease?
Paget’s disease is a condition that affects the growth of bones, causing abnormalities such as unusual bone growth. This often results in widespread pain throughout the body’s muscle and bone system.
When you have Paget’s disease, there’s an increase in the activity of cells that break down bone (osteoclasts), closely followed by an increase in cells that build new bone (osteoblasts). This leads to the formation of disorderly bone that is less dense, weaker, has more blood vessels, and is more prone to break. However, good news is that over three-quarters of people with Paget’s disease don’t show any symptoms. It’s the second most common bone disorder seen in older adults, taking place after osteoporosis. The condition can affect one or more bones, but it usually targets the axial skeleton, which includes the spine, pelvis, and skull. The condition doesn’t spread to other bones, but it can worsen at the site where it already exists. One serious complication of Paget’s disease is the development of a type of cancer called pagetic sarcoma, which can be life-threatening.
The exact cause of Paget’s disease is not known, but it may be linked to certain genes and environmental factors. The disease is most commonly found in Europe, North America, and Australia, and is rare in Asia and Africa. Some viruses have been detected in the bones affected by the disease, but their role in the disease’s development is still unclear.
What Causes Paget Bone Disease?
Some research suggests that Paget’s disease of the bone is caused solely by a group of viruses called paramyxoviruses. However, many studies propose that the primary culprit may be the production of a special protein (a cytokine) called IL-6 found only in the bone marrow of patients with Paget’s disease. This cytokine is involved in inflammation and immune response, influencing the cells responsible for bone resorption (osteoclasts).
Research also shows that genetics plays a significant role in this disease. Studies looking at large groups of people have uncovered a strong genetic link to this disease, suggesting that it can run in families. In fact, brothers and sisters of a person with the disease are at a high risk of developing it. This association is supported by the observation that certain immune system-related genetic markers, known as HLA markers, are often found in people with the disease.
Risk Factors and Frequency for Paget Bone Disease
Paget’s disease typically affects people over the age of 50. Its prevalence has been decreasing worldwide over the past 20 years, and it’s now estimated to affect between 1.5% and 8.3% of the population. It commonly occurs in white people of Northern European ancestry. The disease affects males and females equally, but it is somewhat more common in white males. In the United States, it is thought to affect between 1 and 3 million people, although many don’t show any symptoms. Often, people start showing signs of the disease in their 40s or 50s but it is usually diagnosed a decade later.
- Paget’s disease is typically seen in people aged 50 and above.
- The prevalence of the disease has declined globally in the last 20 years, currently estimated to be between 1.5% and 8.3% of the population.
- The disease is common among white people of Northern European descent.
- Paget’s disease affects both males and females equally, but is somewhat more common in white males.
- In the United States, it affects between 1 to 3 million people, but many have no symptoms.
- It usually starts showing symptoms in the 40s or 50s, but is often diagnosed a decade later.
Signs and Symptoms of Paget Bone Disease
Paget’s disease is commonly diagnosed incidentally during an x-ray, as many patients do not show symptoms. The disease usually affects one bone, with the spine, pelvis, and the femur among the long bones being commonly affected.
In some cases, symptoms do arise, and they include:
- Pain in the bones and joints
- Widespread joint stiffness
- An unusually large skull
- Bone or musculoskeletal deformities
- Hearing loss, if the petrous temporal bone is affected
- Migraines
- Bone fractures
- Heart failure
- Cranial nerve damage
- Headaches
- Deformities of the skull and jaw
The lumbar spine, sacrum, and skull are most often involved in the disease, and pain, especially when weight-bearing, is a common symptom. In some patients, physical examination may reveal bone deformity or angulation, localized pain, increased warmth, altered gait, and balance problems.
Incomplete fractures are common in Paget’s disease, especially in the tibia and femur. Simple injuries could result in fractures, with femur fractures often involving the subtrochanteric region.
A small portion of Paget’s disease patients may develop osteosarcoma, a type of bone cancer, which is often signaled by a sudden increase in swelling or bone pain. This complication can be life-threatening. Additionally, giant cell tumors may form in the facial bones. If vertebral fractures occur, it could potentially lead to acute spinal cord compression.
About one in five patients with Paget’s disease experiences an increase in cardiac output when the axial skeleton is involved. Also, calcified aortic stenosis, a heart valve disease, is commonly observed in these patients.
Testing for Paget Bone Disease
When it comes to diagnosing Paget’s disease, a variety of tests can be helpful. These include a bone scan and a bone x-ray. Additionally, blood tests looking for elevated levels of specific markers that show increased bone breakdown, such as N-telopeptide, can be useful.
Patients with Paget’s disease also frequently show certain patterns in other lab results. They often have high levels of an enzyme in their blood called alkaline phosphatase (ALP). However, levels of serum calcium (calcium in the blood) and phosphate usually stay normal despite the disease.
Some other blood and urine tests can provide further information about the disease. For instance, measurements of ALP in the serum (the clear liquid part of your blood), along with levels of hydroxyproline, C-telopeptide, and N-telopeptide in urine, can be helpful. Procollagen N-terminal peptide is another substance often found in higher levels in the blood of patients with Paget’s disease, since it’s a marker of bone formation.
Sometimes, people with Paget’s disease also have hyperuricemia, which means that there’s too much uric acid in their blood. This condition is common among Paget’s patients because the disease involves a higher turnover of bone. Secondary hyperparathyroidism, which is an overactivity of the parathyroid glands due to high demand for calcium in the body, may occur in approximately 10% of patients with Paget’s disease.
Plain x-rays can help provide more insight into the disease as well. They can show things like increased bone density and thickness, signs of arthritis-like changes, bone expansion, or areas where bone has been destroyed. Bone scans are another helpful tool in diagnosing Paget’s. They can show how extensive the disease is and should be used to monitor the disease’s progress during treatment. Importantly, a bone scan can also pick up early changes in bone before the patient even begins to experience symptoms.
Treatment Options for Paget Bone Disease
Some people diagnosed with Paget’s disease, a condition that disrupts the normal process of bone renewal, may not need any treatment. This can include individuals who don’t have any abnormal blood test results or any active symptoms of the disease.
However, treatment is usually recommended for patients with Paget’s disease if they show signs of abnormal bone defects, if the disease affects their weight-bearing bones (bones that support the body’s weight), if they have deformities in the skull, if their bone changes are rapidly progressing, or if they are experiencing widespread pain.
A variety of treatment options can help to prevent the breakdown and abnormal growth of bones associated with Paget’s disease. Some of the most common treatments include:
– Bisphosphonates: These are drugs that help slow down bone remodeling, which is the process where old bone is replaced by new bone.
– Calcitonin: This medication can also help with bone absorption and provide some pain relief.
– Denosumab: This drug is sometimes used if patients can’t take bisphosphonates, and it generally gives good results.
– Supplements: Taking calcium and vitamin D can provide some relief from symptoms.
– Pain relief: Pain can typically be managed with NSAIDs (Non-Steroidal Anti-Inflammatory Drugs) or acetaminophen, a common mild painkiller.
Surgery is typically only considered if the patient’s Paget’s disease has advanced to osteosarcoma, a type of bone cancer. If osteosarcoma develops, palliative options like removing the affected limb may be considered. When deciding on treatment options, doctors must consider each patient’s unique situation. For instance, younger patients may be offered surgery to remove the tumor and save the limb. However, this might not be a suitable option for older patients with other health concerns.
Paget’s disease can sometimes cause fractures that require radiation and internal fixation, a type of surgery that stabilizes the broken bones, to relieve pain. Chemotherapy, a cancer treatment, is not effective for treating sarcoma, a type of cancer that can develop in people with Paget’s disease. A high number of patients may need further surgery due to complications or unsuccessful initial surgery.
For patients experiencing nerve compression complications, including a serious condition called cauda equina syndrome where the tail of the spinal cord is compressed, a surgery called laminectomy may be necessary. This procedure involves removing a portion of the vertebrae to relieve pressure on the spinal cord or nerves.
What else can Paget Bone Disease be?
When a doctor is trying to diagnose Paget’s disease, they must also consider other diseases that have similar symptoms. These include:
- Osteomalacia, a softening of the bones
- Osteoporosis, a condition where bones become weak and brittle
- Malignancy of the bone, which can be primary or metastatic
- Renal osteodystrophy, bone damage caused by kidney disease
- Osteoarthritis, a type of arthritis that affects the joints
- Osteopenia, a condition where bone density is lower than normal
- Fibrous dysplasia, a disorder where normal bone is replaced with fibrous bone tissue
What to expect with Paget Bone Disease
The outlook for patients treated for Paget’s disease of the bone is generally positive, particularly if the disease is caught in its early stages. While there is no definitive cure for Paget’s disease of the bone, available treatments can control the progression of the disorder, slowing it down or even bringing it to a halt.
Patients dealing with a form of the disease that affects many bones (called polyostotic) may not have outcomes as good as those where only one bone is affected (referred to as monostotic). The negative impacts of the disease are usually due to broken bones, lasting pain, irregular bone shape, and issues with the nervous system.
If Paget’s disease of the bone develops into a kind of cancer known as sarcomatous degeneration, the patient’s survival rate could be significantly low.
Possible Complications When Diagnosed with Paget Bone Disease
Some potential complications associated with certain conditions are:
- Secondary osteoarthritis (a type of arthritis caused by another condition)
- Vertigo (a sensation of feeling off balance)
- Deafness
- Dental malocclusion (an issue with the alignment of the teeth)
- Tinnitus (ringing or noise in the ears)
- Cranial nerve compression (pressure on a nerve in the brain)
- Basilar invagination (a condition where the top of the second bone in the neck pushes upward)
- Cauda equina syndrome (a serious neurological condition affecting bundle of nerve roots at the lower end of the spinal cord)
- Fractures (broken bones)
- Hashimoto thyroiditis (a condition that affects the thyroid gland)
- Osteopetrosis (a rare inherited disorder that makes bones increase in density)
- Dupuytren’s contracture (a hand deformity that usually develops over years)
- The development of osteosarcoma (a type of bone cancer)
- High-output cardiac failure (a condition where the heart can’t pump enough blood to meet the body’s needs)
Preventing Paget Bone Disease
If you’ve been diagnosed with Paget’s disease of the bone, it’s important to understand the symptoms and potential complications. By recognizing the signs of this disease, you can help catch it early and prevent it from advancing. With today’s treatments, there’s a great chance to manage the disease and avoid complications altogether.
You also need to know which of your bones are affected by the disease because different complications can occur depending on the location. For instance, if the disease affects the bones around the ear, you could potentially develop hearing loss. If it affects the bones around the heart, it could lead to heart failure.
Understanding these possibilities helps you stay alert for any unusual symptoms. This way, you can quickly seek medical help to receive appropriate treatment. By doing so, you can manage any potential concerns effectively and promptly.
