Paget's disease is classified according to the affected bone regions and the course of the disease:

1. Monostotic Paget: Affects only a single bone, often the skull bones, pelvis, or long tubular bones.
2. Polyostotic Paget: Affects multiple bones simultaneously or consecutively, often symmetrically.
3. Active phase: Characterized by increased osteoclast activity with rapid bone resorption and remodeling.
4. Inactive phase: Characterized by a slowed bone metabolism and ossification of the affected areas.

The exact causes of Paget's disease are not fully understood, but genetic and environmental factors play a role:

- Genetic predisposition:

- Inheritance of mutations, particularly in the SQSTM1 gene, which affects bone metabolism.

- Viral infections:

- Suspected that latent infections with paramyxoviruses can trigger the disease process.

- Age:

- More common in people over 50 years old.

- Environmental factors:

- Possible triggers such as diet, environmental toxins, or other exogenous influences.

The symptoms vary greatly and depend on the affected bone region and the stage of the disease:

- **Bone pain:** Often the first symptom, especially at rest or at night.

- **Bone deformities:** Coarsened bone structure, e.g., curvatures of the long bones or skull enlargement.

- **Fractures:** Increased susceptibility to fractures due to weakened bone substance.

- **Joint pain:** Secondary osteoarthritis in adjacent joints due to bone deformities.

- **Neurological symptoms:** Pressure on nerves, e.g., in spinal canal narrowings, can lead to pain, numbness, or paralysis.

- **Hearing loss:** Involvement of the skull due to pressure on the auditory nerve.

The diagnosis is made through a combination of clinical findings, laboratory values, and imaging techniques:

- Anamnesis:

- Collection of symptoms, disease progression, and family history.

- Physical examination:

- Palpation and inspection of the affected bone regions for deformities or tenderness.

- Laboratory tests:

- Elevated alkaline phosphatase (AP) as a marker for increased bone turnover.

- Imaging techniques:

- X-ray: Visualization of bone thickening, deformities, and sclerosis.

- Bone scintigraphy: Identification of active disease sites.

- MRI or CT: Detailed imaging in case of suspected complications such as fractures or tumors.

Conservative Therapy

The treatment aims to normalize bone metabolism and prevent complications:

• Medication Therapy:
  • Bisphosphonates: Inhibit osteoclast activity and slow down bone remodeling.
  • Calcitonin: Supports the reduction of bone resorption.
  • NSAIDs: Relief of pain and inflammation.
• Physiotherapy:
  • Exercises to maintain mobility and strengthen muscles.
• Pain Therapy:
  • Complementary measures such as heat treatments or acupuncture.

Surgical Therapy

In severe cases or with complications, surgical interventions may be necessary:

• Fracture Care:
  • Surgical stabilization of bone fractures with plates or screws.
• Correction of Deformities:
  • Surgical procedures to improve function or relieve adjacent joints.
• Joint Replacement:
  • Implantation of prostheses in severe osteoarthritis.

Since the exact causes are not fully known, there are no specific preventive measures. General recommendations include:

1. Regular exercise: Maintaining bone health through physical activity.
2. Calcium and vitamin D intake: Supporting bone metabolism through a balanced diet.
3. Early detection: Regular monitoring of bone values and imaging in case of a family history.
4. Avoidance of risk factors: Limiting smoking and excessive alcohol consumption to promote bone strength.