NNN

Osteomyelitis

Oct 03, 20247 min read

Osteomyelitis is an infection of the bone that results in inflammation, necrosis, and formation of new bone. It may be classified according to what caused the infection:

  1. Hematogenous Osteomyelitis, i.e. from bloodborne spread of infection
  2. Contiguous-focus Osteomyelitis, an infection directly from surgery e.g. through contact with hardware.
  3. Osteomyelitis with Vascular Insufficiency, inflammation and necrosis resulting from ischemia of the bone tissue.

Risk Factors

  1. Older age
  2. Poor nourishment or obesity
  3. Impaired immune systems, chronic illnesses, long-term corticosteroid therapy or use of immunosuppressive agents
  4. Use of illicit IV drugs
  5. Postoperatively, typically occuring within 30 days. This may be incisional or deep (depending on if the incision reaches beyond the deep fascia layer). Implants can become a source of deep postoperative infection within a year.

Pathophysiology

Over half of bone infections are caused by Staphylococcus aureus, and increasingly of the variety that is methicillin-resistant (MRSA). Other pathogens include the gram-positive organisms streptococci and enterococci, followed by gram-negative bacteria, including pseudomonas.

  1. The initial response to infection is inflammation, increased vascularity, and edema.
  2. Within 2 to 3 days, thrombosis of the local blood vessels occur, resulting in ischemia with bone necrosis.
  3. The infection extends into the medullary cavity and under the periosteum and may spread into adjacent soft tissues and joints.
  4. If untreated, a bone abscess forms. The cavity formed by the abscess contains sequestrum (dead bone tissue), which does not easily liquefy and drain.
  5. The cavity fails to drain, collapse and heal.
  6. New bone growth, the involucrum forms and surrounds the sequestrum, resulting in a chronically infected sequestrum remains and produces recurring abscesses throughout the patient’s life. This is known as chronic osteomyelitis.
flowchart TD
1(Infection)
2(Inflammation, Increased Vascularity, Edema)
3(Infection Spreads; Medullary Cavity, Periosteum, Adjacent Soft Tissues/Joints)
4(Bone Abscess Forms, containing Sequestrum)
5(Involucrum forms around the Sequestrum)
6(Chronically Infected Sequestrum results in Recurring Ascesses)
1-->2-->3-->4-->5-->6

Clinical Manifestations

  1. If the infection is bloodborne, onset is often sudden with the clinical manifestations of sepsis: chills, high fever, general malaise, tachycardia.
    • These systemic manifestations may initially overshadow the local manifestations of infection.
    • As infection progresses through the cortex of the bone, the periosteum and soft tissues are infected, producing pain, swelling, and extreme tenderness.
    • The patient may describe a constant, pulsating pain that intensifies with movement as a result of the pressure of collecting purulent material.
  2. If the infection spreads from an adjacent infection or direct contamination, manifestations of sepsis are absent. The area over the infected bone becomes swollen, warm, painful, and tender to touch.
  3. The patient with chronic osteomyelitis presents with a nonhealing ulcer that overlies the infected bone with a connecting sinus that will intermittently and spontaneously drain pus.
  4. Diabetic Osteomyelitis may occur without any external wounds. This may present as a nonhealing fracture. Micro- and macrovascular pathophysiologic changes along with an impaired immune system in diabetics can exacerbate the spread of infection. Any foot ulcer more than 2 cm in diameter is highly suspicious for osteomyelitis.

Diagnostic Examination

  1. X-ray Findings
    • Early: soft tissue edema
    • 2 to 3 weeks: periosteum elevation and bone necrosis
  2. Radioisotope Bone Scans and MRI help with early definitive diagnosis.
  3. Blood studies reveal leukocytosis and an elevated ESR.
  4. Wound and blood cultures are used but only positive in 50% of cases.
  5. Bone Cultures may be used to isolate organisms involved.

Prevention

  1. Delay surgery if any ongoing infection is present.
  2. Prophylactic antibiotics before and after surgery.
  3. Aseptic postoperative wound care and prompt management of soft tissue infections reduces extension of infection to the bone or hematogenous spread.

Management

The initial goal of therapy is the control and halt the infective process. General supportive measures e.g. hydration, dieting, and correction of anemia are instituted. Immobilization of the infected area decreases discomfort and to prevent pathologic fractures of the weakened bone.

  1. Pharmacologic: because of the avascularity and immune system having difficulty accessing the bone, infections are harder to eradicate.
    • Antibiotic Therapy is longer-term, typically continuing for 6 to 12 weeks. Initially administered intravenously, the antibiotics may be given orally after the infection appears to be controlled.
  2. Surgical: chronic infection that does not respond to antibiotic therapy is indicative of surgical debridement. All dead and infected cartilage and bone must be removed before permanent healing can occur.
    • Exposure of the infected bone and removal of the purulent and necrotic material.
    • Sequestrectomy: removal of enough involucrum to enable the surgeon to remove the sequestrum.
    • Saucerization: if enough bone material is removed, the deep cavity is shaped into a shallow saucer.
    • Saline Irrigation is required if debris remains, typically not exceeding beyond a week.
    • The resulting cavity may be tightly closed or packed and closed later by granulation or grafting (with cancellous bone graft). Large cavities may be filled with a vascular muscle flap or bone transfer.
    • Internal fixation or external supportive devices may be required to prevent pathologic fractures as debridement weakens the bone.

Nursing Process

Assessment

  • An acute onset of signs and symptoms e.g. localized pain, edema, erythema, fever.
  • Recurrent drainage of an infected sinus with associated pain, edema, and low-grade fever.
  • Assess for risk factors: old age, diabetes, long-term corticosteroid therapy, etc.
  • History of previous injury, infection, or orthopedic surgery
  • Altered gait as the patient attempts to avoid pressure and movement of the area.
  • Generalized malaise as a systemic reaction to acute hematogenous osteomyelitis.
  • Physical Examination reveals inflamed, markedly edematous, and warm tender area. Purulent drainage may be noted.
  • Elevated temperature is present in infection, but may only be present in the afternoon or evening for those with chronic osteomyelitis.

Diagnosis

  1. Acute pain associated with inflammation and edema
  2. Impaired mobility associated with pain, use of immobilization devices, and weight-bearing limitations
  3. Risk for infection: bone abscess formation
  4. Lack of knowledge associated with treatment regimen

Planning, Goals, and Intervention

Goals include pain relief, improved physical mobility, control and eradication of infection, and knowledge of treatment regimen.

  1. Relieving Pain:
    • Immobilization via splint reduces pain and muscle spasming. This entails monitoring of the skin and neurovascular status of the affected extremity.
    • Great care and gentleness is observed in handling wounded extremities.
    • Elevation reduces swelling and associated discomfort.
    • Analgesics and other pain-reducing agents when prescribed may also be used.
  2. Improving Physical Mobility:
    • The patient must understand the rationale for activity restrictions.
    • ROM Exercises for the joints above and below the affected region.
    • Full participation in ADLs should be encouraged to promote general well-being.
  3. Controlling the Infectious Process: monitor the response to antibiotic therapy; observe the IV access site for phlebitis, infection, or infiltration.
    • In long-term intensive antibiotic therapy, monitor the patient for superinfection (oral or vaginal candidiasis, loose or foul-smelling stools), and for development of additional painful sites or sudden increases in body temperature.
    • If surgery is necessary, ensure adequate vascular flow (wound suction for fluid accumulation, elevation for venous drainage).
    • Ensure adherence to weight-bearing restrictions.
    • Maintain the aseptic technique when changing dressings to promote healing and to prevent cross contamination.

Evaluation

  1. Experiences pain relief: reports decreased pain at rest, experiences no tenderness, and experiences minimal discomfort with movement.
  2. Increases in safe physical mobility: participates in self-care activities, maintains full function of unimpaired extremities, demonstrates safe use of immobilizing and assistive devices, and modifies environment to promote safety and to avoid falls.
  3. Shows absence of infection: takes antibiotics as prescribed, reports normal temperature, exhibits no edema, drainage is absent, normal WBC/ESR results, and wound cultures are negative.

Backlinks

Graph View