Osteonecrosis

Osteonecrosis

OVERVIEW:

Death of the cellular components of bony tissue

System(s) affected: Musculoskeletal
Genetics: The underlying condition of hemoglobinopathies, especially sickle cell disease, diabetes, and type II or IV hyperlipemia are inheritable and associated with a high incidence of osteonecrosis. Other forms have no proven genetic relationship.
Incidence/Prevalence in USA: Dependent upon the underlying condition
Predominant age: 3rd to 6th decade
Predominant sex: Male > Female

SIGNS AND SYMPTOMS:

• The symptoms may be acute as in osteonecrosis of sickle cell disease or renal transplant. Usually insidious in other forms. Diagnosis may not be made for two years after onset of symptoms.
• Pain, the prominent symptom, is made worse with activity
• Loss of motion of the affected joint
• Stiffness (especially early morning)
• Swelling if the involved joint is superficial
• Locking may occur if a loose body has developed
• Proximal femur is the most common site and more prevalent in males in the 3rd-6th decade
• The distal femur, especially the medial femoral condyle, is the second most frequent site. This area is unique in that night pain is a prominent early symptom. Most common in females in the 6th-7th decade.
• Other sites in decreasing frequency are the proximal humerus, talus, carpal lunate (Kienbock's disease) and the humeral capitulum

CAUSES:

• Idiopathic
• Fractures, especially the femoral neck
• Traumatic (fractures, dislocation)
• Dislocations
• Legg-Calve-Perthes (seen in 6-12 year age group)
• Hemoglobinopathies (especially sickle cell disease)
• Metabolic (hemoglobinopathies, alcohol, steroids, renal failure/transplantation)

RISK FACTORS:

• Gaucher's disease - especially likely as a postoperative infection
• Diabetes mellitus
• Alcoholism - the most frequent cause
• Type II or IV hyperlipemia
• Cortisone therapy (may be seen with Cushing's disease)
• Obesity
• Oral contraceptives
• Organ transplant, especially kidney
• Pregnancy
• Decompression sickness (bends)

DIAGNOSIS

DIFFERENTIAL DIAGNOSIS:

Rheumatoid arthritis, septic necrosis and severe secondary hyperparathyroidism. A crescent sign (a linear subchondral lucency indicates collapse of subchondral bone. Patchy lucencies reflect resorption; patchy sclerosis indicates growth of new bone over the scaffolding of dead trabeculae) in these conditions may occur because the bone may be so soft that it collapses producing a crescent sign.

LABORATORY:

N/A

Drugs that may alter lab results: N/A
Disorders that may alter lab results: N/A

PATHOLOGICAL FINDINGS:

The subchondral fracture occurs during bone repair as necrotic bone is resorbed. Later, a collapse of the bone occurs with subsequent irregularities at the joint surface. This will eventually produce osteoarthritic changes.

SPECIAL TESTS:

Bone scan shows decreased bone uptake (sometimes increased uptake depending on the stage). Later, the uptake increases as reparative processes begin within the bone.

IMAGING:

MRI will show a decreased signal intensity of the involved bone and is the most sensitive diagnostic exam.

DIAGNOSTIC PROCEDURES:

The presence of a crescent sign is practically diagnostic (see Differential Diagnosis of osteonecrosis). It is caused by a subchondral fracture.

TREATMENT

APPROPRIATE HEALTH CARE:

Outpatient normally; inpatient if surgery indicated

GENERAL MEASURES:

• Only four conditions can be treated to decrease the incidence of osteonecrosis
• Alcoholism - abstinence is obvious, but quite difficult to attain
• Dysbarism - new tables of decompression, if followed, will lower osteonecrosis incidence of divers
• Transplant patients - decreased doses of cortisone and regulation of calcium and phosphorous metabolism
• Sickle cell disease - treat a crisis vigorously with hydration, possible exchange transfusion and oxygenation, especially hyperbaric oxygen

SURGICAL MEASURES:

Bone grafts, arthroplasty, allografts and arthrodesis may be used, dependent upon the joint involved

ACTIVITY:

As tolerated

DIET:

No special diet

PATIENT EDUCATION:

The patient should be instructed in the use of crutches and/or canes when the lower extremity is involved. Proper use of a walking cane can decrease the pressure on the femoral head 20-30% when walking.

MEDICATIONS

DRUG(S) OF CHOICE:

• NSAIDs - consistent with the underlying disease may be used for painful episodes
• Acetaminophen - 500 mg qid can be quite helpful in alleviating symptoms

Contraindications: See manufacturer's profile of each drug
Precautions: NSAIDs - if history of peptic ulcer is present, the use of ranitidine (Zantac) 150 mg bid or 300 mg hs can be given. Misoprostol (Cytotec) 100 µg bid will usually prevent gastritis (not needed with acetaminophen).
Significant possible interactions: See manufacturer's profile of each drug

ALTERNATIVE DRUGS:

Other H2-receptor antagonists in patients with a history of peptic ulcer disease

FOLLOW UP

PATIENT MONITORING:

X-rays should be made every 12-18 months, more frequently if symptoms become more severe

PREVENTION/AVOIDANCE:

Early diagnosis and treatment of underlying disease

POSSIBLE COMPLICATIONS:

• Progression of disease
• The progression of osteonecrosis leads to osteoarthritis of the involved joint to a varying degree. Arthroplasty of the hip carries a much poorer prognosis than osteoarthritis alone. It should be postponed as long as possible.

EXPECTED COURSE AND PROGNOSIS:

Gaucher's disease is associated with a high risk of infection following surgery

MISCELLANEOUS

ASSOCIATED CONDITIONS:

N/A

AGE-RELATED FACTORS:

Pediatric: Legg-Calve-Perthes occurs in the 6-12 year age group. Prognosis is better in younger patients.
Geriatric: N/A
Others: N/A

PREGNANCY:

Is a risk factor

SYNONYMS:

• Idiopathic osteonecrosis
• Avascular necrosis
• lunatomalacia, Kienbock's disease
• Subchondral fracture

ICD-9-CM:

730.1 Osteonecrosis

(see images)

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Medical Diagnosis » O » Osteonecrosis