It develops when localised areas of bone undergo excessive and disorganised remodelling, with bone being broken down and rebuilt too quickly and in a chaotic pattern. This results in bone that is larger, less dense and more fragile than healthy bone, even though the total amount of bone in the affected area may be increased. Paget's disease can affect one bone or several, and progresses slowly over many years. It is often discovered incidentally, but in some cases it causes bone pain, deformity or complications affecting nearby joints and nerves. Without appropriate assessment and management, Paget's disease can lead to fractures, joint damage, nerve compression and, rarely, changes in the affected bone requiring further investigation.
What is Paget's disease?
Paget's disease of bone is a chronic condition in which the normal cycle of bone breakdown and formation becomes overactive and disorganised in specific areas of the skeleton. This produces bone that is structurally abnormal, enlarged and prone to deformity, pain and fracture.
Bone is a living tissue that is constantly being remodelled:
- Throughout life, old bone is broken down by cells called osteoclasts and new bone is built by cells called osteoblasts.
- In Paget's disease, osteoclast activity becomes excessive in affected areas, and the osteoblasts respond by rapidly laying down new bone.
- This rapid, disorganised turnover produces bone that is larger and less well-organised than normal bone, making it weaker despite its increased size.
- Paget's disease most commonly affects the pelvis, spine, skull, femur and tibia, and can involve a single bone or multiple sites.
What are the causes of Paget's disease?
The exact cause of Paget's disease is not fully understood, but it is thought to result from a combination of genetic and environmental factors affecting bone cell activity. Risk factors for Paget's disease include:
Genetic and demographic factors
- Increasing age, with the condition rarely occurring before the age of 40
- A family history of Paget's disease, present in a significant proportion of cases
- Male sex, which is affected slightly more often than female sex
- Northern European ancestry, particularly the UK
Possible environmental and medical factors
- Previous viral infection, which has been suggested as a possible trigger in genetically susceptible individuals
- Certain gene mutations, including changes in the SQSTM1 gene, identified in some familial cases
What are the symptoms of Paget's disease?
Many people with Paget's disease have no symptoms, and the condition is often found incidentally on an X-ray or blood test performed for another reason. When symptoms do occur, they may include:
- Persistent bone pain, often deep and aching, which may be worse at rest or at night
- Bone deformity, such as bowing of the leg or enlargement of the skull
- Increased warmth over an affected bone, due to increased blood flow
- Joint pain or stiffness, particularly when Paget's disease affects bone near a joint
- Hearing loss, headaches or nerve-related symptoms, when the skull or spine is affected
- Fractures occurring after relatively minor injury
Because Paget's disease is often asymptomatic, it may only come to light through incidental findings or as a cause of unexplained joint or bone pain.
When to Seek Medical Advice?
You should seek specialist assessment if you have:
- Persistent, unexplained bone or joint pain
- A known family history of Paget's disease
- Been told you have raised alkaline phosphatase or an abnormal bone X-ray
- Noticed bone deformity, swelling or increased warmth over a bone
Early assessment allows the condition to be monitored appropriately and treated where necessary, reducing the risk of complications such as fracture, deformity or joint damage.
How Paget's disease is diagnosed?
Diagnosis is based on a combination of clinical assessment, blood tests and imaging. Dr Nuttall will begin with a detailed review of your symptoms, medical history, family history and a physical examination.
Investigations for Paget's disease may include:
- Initial assessment
- Blood tests, particularly alkaline phosphatase, a marker of bone turnover that is typically raised in active Paget's disease, along with calcium and vitamin D levels
- X-rays of the affected bone, which typically show characteristic changes in bone size, shape and structure
- Further imaging and specialist investigations
- Bone scan (scintigraphy), used to identify the number and location of bones affected
- CT or MRI scanning, where more detailed assessment of a specific site is required, or if a complication is suspected
- Further investigations if there is diagnostic uncertainty or concern about a secondary complication
How to treat Paget's disease?
Treatment is aimed at controlling disease activity, relieving symptoms, preventing complications and preserving bone strength and joint function. The approach is tailored to the site and extent of disease, symptoms and overall health.
Treatment options may include:
Medical management
- Bisphosphonates, typically given as an intravenous infusion of zolendronic acid, which are highly effective at suppressing abnormal bone turnover and are the mainstay of treatment for active disease
- Oral bisphosphonates, used less commonly but considered in some cases
- Pain relief medication, to manage bone or joint pain
- Calcium and vitamin D supplementation, to support bone health, particularly where levels are low
Monitoring and supportive care
- Regular monitoring of alkaline phosphatase and symptoms, to assess treatment response and disease activity over time
- Physiotherapy, to maintain joint mobility and muscle strength where joints are affected
- Orthopaedic review, where deformity, fracture or significant joint damage requires surgical assessment
- Hearing assessment, where the skull is affected and hearing changes are present
Dr Nuttall will tailor treatment to control disease activity, relieve symptoms, and reduce the risk of long-term complications affecting your bones and joints.
