Osteomyelitis - Causes, Symptoms and Treatments

A pyogenic bone infection, osteomyelitis may be chronic or acute. It commonly results from a combination of local trauma-usually quite trivial but resulting in hematoma formation-and an acute infection originating elsewhere in the body. Although osteomyelitis often remains localized, it can spread through the bone to the marrow, cortex, and periosteum.

Acute osteomyelitis is usually a blood­borne disease, which most often affects rapidly growing children. Chronic osteomyelitis (rare) is characterized by multiple draining sinus tracts and metastatic lesions.

Osteomyelitis occurs more often in children than in adults-and particularly in boys-usually as a complication of an acute localized infection. The most common sites in children are the lower end of the femur and the upper end of the tibia, humerus, and radius. In adults, the most common sites are the pelvis and vertebrae, generally the result of contamination associated with surgery or trauma.

The incidence of both chronic and acute osteomyelitis is declining, except in drug abusers. With prompt treatment, the prognosis for acute osteomyelitis is very good; for chronic osteomyelitis, which is more prevalent in adults, the prognosis remains poor.

Causes of Osteomyelitis:

The most common pyogenic organism in osteomyelitis is Staphylococcus aureus; others include Streptococcus pyogenes, Pneumococcus, Pseudomonas aeruginosa, Escherichia coli, and Proteus vulgaris. Typically, these microbes tind a culture site in a hematoma from recent trauma or in a weakened area, such as the site of local infection (for example, furunculosis), and spread directly to bone.

As the microbes grow and form pus within the bone, tension builds within the rigid medullary cavity, forcing pus through the haversian canals. This forms a subperiosteal abscess that deprives the bone of its blood supply and eventually may cause necrosis. In turn, necrosis stimulates the periostcum to create new bone (involucrum); the old bone (sequestrum) detaches and works its way out through an abscess or the sinuses. By the time sequestrum forms, osteomyelitis is chronic.

Signs and symptoms of Osteomyelitis:

Onset of acute osteomyelitis is usually rapid, with sudden pain in the affected bone, and tenderness, heat, swelling, and restricted movement over it. Associated systemic symptoms may include tachycardia, sudden fever, nausea, and malaise. Generally, the clinical features of both chronic and acute osteomyelitis are the same, except that chronic infection can persist intermittently for years, flaring up spontaneously after minor trauma. Sometimes, however, the only symptom of chronic infection is the persistent drainage of pus from all old pocket in a sinus tract.

Diagnosis for Osteomyelitis:

Patient history, physical examination, and laboratory tests help to confirm osteomyelitis.

1.White blood cell count shows leukocytosis.

2.Erythrocyte sedimentation rate and Creactive protein (CRP) arc elevated; however, CRP appears to be a better diagnostic tool.

3.Blood cultures identify the causative organism.

X rays may not show bone involvement until the disease has been active for some time, usually 2 to 3 weeks. Bone scans can detect early infection. Computed tomography scan and magnetic resonance imaging may be necessary to delineate the extent of infection. Diagnosis must rule out poliomyelitis, rheumatic fever, myositis, and bone fractures.

Treatment of Osteomyelitis:

Treatment varies for acute and chronic osteomyelitis. Acute osteomyelitis should bc treated before a definitive diagnosis. Treatment includes administration of large doses of I.V. antibiotics (usually a penicillinase-resistant penicillin, such as nafcillin or oxacillin, or a cephalosporin) after blood cultures are taken; early surgical drainage to relieve pressure buildup and sequestrum formation; immobilization of the affected bone by plaster cast, traction, or bed rest; and supportive measures, such as administration of analgesics and I.V. fluids.

If an abscess forms, treatment includes incision and drainage, followed by a culture of the drainage. Antibiotic therapy to control infection may include administration of systemic antibiotics; intracavitary instillation of antibiotics through closed-system continuous irrigation with low intermittent suction; limited irrigation with blood drainage system with suction (Hemovac); or local application of packed, wet, antibiotic-soaked dressings.

In chronic osteomyelitis, surgery is usually required to remove dead bone and to promote drainage (saucerization). The prognosis is poor even after surgery. Patients are often in great pain and require prolonged hospitalization. Resistant chronic osteomyelitis in an arm or leg may necessitate amputation.

Some facilities also use hyperbaric oxygen to increase the activity of naturally occurring leukocytes.

Free tissue transfers and local muscle flaps are also used to fill in dead space and increase blood supply.

Special considerations and Prevention tips of Osteomyelitis:

The caregiver's major concerns are to control infection, protect the bone from injury, and offer meticulous supportive care .

1. Use strict aseptic technique when changing dressings and irrigating wounds.

2. If the patient is in skeletal traction for compound fractures, cover insertion points of pin tracks with small, dry dressings, and tell him not to touch the skin around the pins and wires.

3. Administer I.V. fluids to maintain adequate hydration as necessary.

4.Provide a diet high in protein and vitamin C.

5.Assess vital signs and wound appearance daily, and monitor daily for new pain, which may indicate secondary infection.

6. Carefully monitor suctioning equipment. Keep containers filled of solution being instilled. Monitor the amount of solution instilled and suctioned.

7. Support the affected limb with firm pillows. Keep the limb level with the body; don't let it sag.

8. Provide good skin care. Turn the patient gently every 2 hours and watch for signs of developing pressure ulcers.

9. Provide good cast care. Support the cast with firm pillows and "petal" the edges with pieces of adhesive tape or moleskin to smooth rough edges.

10. Check circulation and drainage. If a wet spot appears on the cast, circle it with a marking pen and note the time of appearance (on the cast). Be aware of how much drainage is expected. Check the circled spot at least every 4 hours. Watch for any enlargement.

11. Protect the patient from mishaps, such as jerky movements and falls, which may threaten bone integrity.

12. Be alert for sudden pain, crepitus, or deformity. Watch for any sudden malposition of the limb, which may indicate fracture.

13. Provide emotional support and appropriate diversions.

14. Stress the need for follow-up examinations.

15. Instruct the patient to seek prompt treatment for possible sources of recurrence­blisters, boils, styes, and impetigo.

Before discharge, teach the patient how to protect and clean the wound and, most importantly, how to recognize signs of recurring infection (increased temperature, redness, localized heat, and swelling).