OSTEITIS DEFORMANS (PAGET’S DISEASE)

OSTEITIS DEFORMANS (PAGET’S DISEASE) – Etiology, Pathophysiology, Signs and Symptoms, Diagnostic Evaluations and Management

Paget’s disease of bone disrupts the body’s normal bone recycling process, in which old bone tissue is gradually replaced with new bone tissue.  Overtime, the affected bones may become fragile and weak. Page’t disease of bone most commonly occurs in the pelvis, skull, spine and legs. The involved bone can be soft, leading to weakness and bending of the pelvis, low back (spine), hips, thighs, head and arms.

ETIOLOGY

• Both genetic and environmental factors are thought to play a role
• About 15% of people with Paget’s disease have a family history
• Autosomal dominant inheritance has also been described in some families
• Mutations have been identified in four genes that cause Paget’s disease
• Mechanical stress may play a role
• Paramyxovirus infection (including measles and respiratory syncytial virus) has been suggested as a possible trigger but this has been disputed.

PATHOPHYSIOLOGY

The metabolic hyperactivity is the main feature of Paget’s disease —- the primary abnormality is believed to be an intense focal resorption of normal bone by abnormal osteoclasts, leading to creation of voids and cavities in the bone —- these osteoclasts are abnormal in size, activity, and quantity and have excess nuclei —- the physiological compensatory mechanism for repair results in the deposition of fibrotic tissue and even new bone in the cavities by osteoblasts —- the osteoblast activity is so rapid that newly formed bone is not organized and remains irregular and woven in nature —- the newly formed woven bone is less resistant and more elastic than typical lamellar bone, and hence prone to deformity and micro-fractures, especially in the weight-bearing extremities —- there is a high degree of vascularity in the pagetoid bone cause of pain

Paget’s disease Evolves Through three Distinct Phases

1. An initial, short-lived burst of multinucleate osteoclastic activity causing bone resorption
2. A mixed phase of both osteoclastic and osteoblastic activity, with increased levels of bone turnover leading to deposition of structurally abnormal bone
3. A final chronic sclerotic phase, during which bone formation outweighs bone resorption

SIGNS AND SYMPTOMS

Most people who have Page’s disease of bone experience no symptoms. When symptoms do occur, the most common complaint is bone pain which may includes:

• Pelvis: Paget’s disease of bone in the pelvis can cause hip pain
• Skull: an overgrowth of bone in the skull can cause hearing loss or headaches
• Spine: if spine is affected, nerve roots can become compressed. This can cause pain, tingling and numbness in an arm or leg
• Leg: as the bones weaken, they may bend. Enlarged and misshapen bones in legs can put extra stress on nearby joints, which may cause wear-and-tear arthritis in knee or hip.

DIAGNOSTIC EVALUATIONS

• Bone-specific alkaline phosphatase (BSAP) levels are raised
• Urinary excretion of deoxypyridinoline and N-telopeptide are elevated
• Serum calcium, phosphorus, and parathyroid hormone levels are usually normal but immobilization may lead to hypercalcemia
• X-rays may show a number of signs of both osteolysis and excessive bone formation occur
• Radionuclide bone scans can show the extent of the disease
• Bone biopsy may be needed if malignant change is suspected

MANAGEMENT

Treatment approaches can focus on providing physical assistance, including the addition of wedges in the shoe, walking aids and the administration of physical therapy and pharmacotherapy

Pharmacotherapy

• Nonsteroidal anti-inflammatory drugs (NSAIDs) and paracetamol may be effective for pain
• Anti-resorptive therapy is with either bisphosphonates or calcitonin
• Biphosphonates:

Oral or intravenous bisphosphonates are the main stay of treatment

They are thought to reduce bone turnover, improve bone pain, promote healing of osteolytic lesions and restore normal bone histology

Newer bisphosphonates such as zoledronic acid may help to better achieve metabolic control of the disease and so improve these statistics

Pamidronate, risedronate, and zoledronic acid are preferred

Any calcium and vitamin D deficiency needs to be corrected before starting a bisphosphonate to avoid hypocalcemia

All oral medications should be taken with a large glass of water (6-8 oz) upon arising in the morning. Patients should remain upright for the next 30 minutes and not eat until that time has passed. Any of these treatments can be repeated if necessary. Side effects of these medicines may involve heartburn and sometimes increasing bone pain for a short period of time

There are also injectable medications. Injectable medications that can be given for Paget’s include:

• Pamidronate: which is injected in the vein once a month or once every few months? The injection takes a few hours. Unusually, there can be inflammation of the eye or loss of bone around the teeth (osteonecrosis)
• Zoledronate: this is injected in the vein once a year
• Calcitonin, a hormone that is injected under the skin several times a week

COMPLICATIONS

Complications from Paget’s disease depend on the site affected and the activity of the disease:

• Bone pain
• Bone deformity, kyphosis, frontal bossing of the skull, an enlarged maxilla, an increase in head size
• Pathological fractures
• Osteoarthritis
• Deafness and tinnitus may be due to compression of cranial nerve VIII
• Spinal stenosis
• Nerve compression syndromes

NURSING MANAGEMENT

1. Acute pain related to nerve compression, muscle spasm

Interventions

• Assess complaints of pain, location, duration of attacks, precipitating factors which aggravate
• Maintain bedrest, semi-Fowler position to the spinal bones, hips and knees in a state of flexion, supine position
• Use logroll (board) during a change of position
• Auxiliary mounting brace
• Limit activity during the acute phase according to the needs
• Teach relaxation techniques
• Collaboration: analgesics, traction, physiotherapy

• Impaired physical mobility related to pain, muscle spasms, and damage neuro-muskulus restrictive therapy

Interventions

• Give patients to perform passive range of motion exercises and active
• Assist patients in ambulation activity progressively
• Provide good skin care, massage point pressure after rehap change of position. Check the state of the skin under the brace with a specific time period
• Note the emotional responses and behaviors in immobilizing
• Demonstrate the use of auxiliary equipment such as a cane
• Collaboration: analgesic