Note

It’s important to know that in children, infections typically affect the long bones. Conversely, in adults, the vertebrae (bones of the spine) and the pelvis are the most frequent sites of infection.

Acute osteomyelitis is more commonly seen in children due to the abundant blood supply to their developing bones. When osteomyelitis occurs in adults, it’s often associated with weakened host defenses caused by conditions such as general poor health, intravenous drug use, infections originating from dental root canals, or other illnesses that suppress the immune system.

Wald Vogel Classification of Osteomyelitis

Osteomyelitis can be categorized based on:

1. Duration of Infection

2. How the bone becomes infected

Duration of Infection

Acute osteomyelitis (suppurative osteomyelitis): This phase generally refers to the infection before significant bone death has occurred. Early events include tissue swelling (edema), the formation of pus, blood vessel congestion, and the blockage (thrombosis) of small blood vessels.

Chronic osteomyelitis (suppurative osteomyelitis phase): This stage involves infection within the bone itself and in the tissues surrounding bone that has died. It can arise from recurring acute cases and is characterized by large areas of reduced blood flow (ischemia), tissue death (necrosis), and the presence of dead bone fragments called sequestra.

N.B.: Untreated acute osteomyelitis can progress to the chronic form. This happens because the infection and the resulting inflammation obstruct blood vessels, leading to bone death. Chronic osteomyelitis is generally more challenging to treat.

Sequestra: This refers to a piece of dead bone that separates from healthy bone.

Mechanism of Bone Infection

Hematogenous: This occurs when bacteria travel to the bone through the bloodstream. It’s the most common way children develop osteomyelitis.

Associated with vascular insufficiency: Infections can arise in individuals with conditions that reduce blood flow, such as in the feet of diabetic patients or those with peripheral vascular disease.

Contiguous: This type of infection results from the direct introduction of bacteria from a nearby site of infection. Examples include post-traumatic osteomyelitis following an injury or infections originating from adjacent tissues or prosthetic devices.

Pathophysiology of Osteomyelitis

Osteomyelitis begins when infectious bacteria invade the bone. These bacteria can reach the bone via the bloodstream, spread from a nearby infection, or be introduced directly through contamination. Risk factors that increase susceptibility include open wounds over a bone, open fractures, recent surgical procedures, injections near bone, medications that weaken the immune system, and pre-existing medical conditions like diabetes.

Generally, microorganisms infect the bone through one of three primary routes:

• Through the bloodstream (hematogenously): This is the most frequent mechanism.

• From nearby infections: Such as in cases of cellulitis (skin infection).

• Penetrating trauma: This includes injuries and procedures like joint replacements, internal fixation of fractures, or infections stemming from advanced gum disease (peripheral periodontitis) in teeth.

When the infection originates in the bloodstream, it commonly affects the metaphysis, the region of growth in a long bone. Once the bone is infected, white blood cells (leukocytes) migrate to the area to engulf the infectious organisms. In this process, they release enzymes that break down bone tissue.

The accumulating pus spreads into the bone’s blood vessels, hindering blood flow. This leads to areas of dead, infected bone known as sequestra, which are central to chronic infection. The body often attempts to form new bone around these necrotic areas, and this newly formed bone is called the involucrum.

Microscopic examination of these areas of dead bone is a key factor in distinguishing between acute and chronic osteomyelitis.

The illness typically has a rapid onset, often within 48 hours. Initially, there is bone pain and significant tenderness upon touch, but without visible signs of inflammation. As the infection spreads beneath the periosteum (the outer layer of bone), local and systemic signs of infection become apparent. Pus then accumulates within the bone and surrounding soft tissues. The bone’s appearance on X-rays doesn’t change for the first 10 to 14 days, making initial radiographs useful as a baseline for comparison and to rule out other conditions like Ewing’s sarcoma or leukemia. A blurring of the lines between soft tissue layers might be visible. Osteomyelitis encompasses the infection of all components of the bone, including the bone marrow. In its chronic form, it can result in the thickening and hardening of bone (sclerosis) and deformities.

PREDISPOSING FACTORS

• Pyomyositis (bacterial infection of muscle)

• Cellulitis (skin infection)

• Sickle-cell disease (especially during a thrombotic crisis) (Staphylococcus aureus is a common cause, but Salmonella is also frequent in these patients)

• Diabetes

• Intravenous drug use

• Previous removal of the spleen

• Age (both young children and older adults are at higher risk)

• Immune suppression (weakened immune system)

• Autoimmune disorders

• Systemic infections (infections affecting the entire body)

Signs and Symptoms of Osteomyelitis

Acute osteomyelitis

• Symptoms typically develop over a few days.

• Fever is common, often high, but may be absent, especially in newborns.

• Pain in the affected limb is usually severe.

• Tenderness and increased warmth can be felt at the infection site, accompanied by swelling of the surrounding tissues and joint.

• Difficulty or inability to use the affected limb.

• Commonly affects children aged 4 years and older with reduced immunity, but adults can also be affected.

• A history of injury might be reported but can be misleading, especially if there is no fever.

• General feeling of illness (malaise).

• Redness of the limb.

• Swelling (edema) of the limb.

Chronic osteomyelitis

• May present with pain, redness of the skin (erythema), or swelling, sometimes accompanied by a draining sinus tract (an abnormal channel).

• Deep or extensive open sores (ulcers) that don’t heal after several weeks of appropriate care, such as in diabetic foot ulcers, and fractures that fail to heal should raise suspicion of chronic osteomyelitis.

Differential diagnosis

• Infection of the joints.

• Injury (trauma) to a limb, fracture (in children).

• Bone cancer (osteosarcoma, particularly around the knee area in children and adults).

Management of Osteomyelitis

Management can involve medication, surgery, or a combination of both.

Aims of management

1. To maintain the function of the limb and nearby joints.

2. To prevent further complications from developing.

Admission

• The child is typically admitted to the pediatric ward.

• A thorough medical history is taken, including the patient’s name, sex, address, nationality, past medical conditions, and previous surgeries.

Assessment

• Vital signs such as temperature (T), pulse (P), respiration rate (R), and blood pressure (BP) are measured and recorded.

• The affected limb is examined for redness, warmth, swelling (edema), and a general physical examination is conducted from head to toe.

• The doctor is informed, who will then order necessary investigations.

Investigations / Diagnosis

Diagnosis is based on physical examination, laboratory tests, and radiological findings.

• X-ray findings:

  • Usually appears normal in the first 1-2 weeks.

  • Loss of bone density (rarefaction) becomes visible at approximately 2 weeks.

  • A thin “white” line may appear on the surface of the infected part of the bone, indicating periosteal reaction.

  • Later, a piece of dead bone (sequestrum) might be visible.

• Blood tests: Complete blood count (CBC), erythrocyte sedimentation rate (ESR), and culture and sensitivity (C&S) tests are performed to identify the type of bacteria.

Medical Management

• Immobilize the affected limb, often using a splint.

• Elevate the affected limb.

• Provide pain and fever relief using medications like paracetamol or ibuprofen.

• Typically, patients require several weeks of antibiotic treatment to effectively clear the infection.

• Drain any infected sites if necessary.

• Immobilize or stabilize the bone if required.

• Administer intravenous antibiotics, such as Cloxacillin: For children under 12 years old, the dosage is 50 mg/kg every 6 hours; for those above 12 years old, it’s 500 mg intravenously every 6 hours for 2 weeks. This may be followed by oral antibiotics for at least 4 weeks (and potentially up to 3 months) if the initial treatment is not successful.

• Alternatively, Ceftriaxone at a dosage of 50mg-100mg/kg may be used for approximately 10 days. Vancomycin, penicillin, and ciprofloxacin are other options depending on the results of the culture and sensitivity tests.

• Administer pain relievers (analgesics) based on the severity of the pain, such as ibuprofen, acetaminophen, or morphine for severe pain.

• If there’s no improvement after 48-72 hours of antibiotic therapy, surgical intervention is considered.

Surgical intervention may be indicated in the following situations:

• Drainage of pus collections under the periosteum or in the soft tissues.

• Drainage of pus within the bone marrow cavity.

• Removal of dead bone tissue and localized pus.

• Debridement (cleaning) of nearby sites of infection (which also requires antibiotic therapy).

• Removal of sequestra (dead bone fragments).

• Surgical cleaning of the area to remove necrotic tissue.

• Failure to improve after 48-72 hours of antibiotic treatment.

Chronic osteomyelitis

• Management involves both surgery and antibiotics.

• Continue administering intravenous antibiotics such as ceftriaxone (50mg-100mg/kg for about 10 days), vancomycin, penicillin, or ciprofloxacin, guided by culture and sensitivity results.

Nursing Care

Nursing Diagnosis

1. Ineffective Tissue Perfusion Related to: Inflammatory reaction, Thrombosis of vessels, Tissue destruction, Edema, Abscess formation As evidenced by: Bone necrosis, Continuation of the infectious process, Delayed healing, Pain, Erythema, Swelling, Altered sensation in the affected area, Weak peripheral pulses.

   Ineffective Tissue Perfusion Interventions:

   1. Improve blood flow to the site, as it delivers nutrients, removes waste, and promotes healing. Optimal blood flow through vessels is crucial for perfusion.

   2. Manage underlying chronic conditions and lifestyle factors that impair blood flow, such as diabetes, peripheral vascular disease, sickle cell disease, neuropathy, smoking, and malnutrition. These should be addressed before surgery.

   3. Provide DVT prophylaxis (measures to prevent blood clots), administering prescribed anticoagulants to enhance circulation.

   4. Prepare the patient for potential surgery if needed to restore blood flow, such as debridement or vascular surgery.

   5. Implement pressure ulcer prevention strategies for immobile patients to reduce the risk of osteomyelitis.

2. Hyperthermia Related to: Increased metabolic rate, Infection, Inflammatory response, Trauma As evidenced by: Increased body temperature, Warmth to touch, Flushed skin, Tachypnea, Tachycardia.

   Hyperthermia Interventions:

   1. Provide a tepid sponge bath to lower body temperature and provide comfort.

   2. Apply a cooling blanket to reduce internal body temperature through surface cooling, while closely monitoring to prevent a rapid temperature drop.

   3. Initiate prescribed antibiotic therapy, emphasizing to patients that long-term treatment may be necessary.

   4. Educate the patient and family about recognizing symptoms like fever, chills, skin warmth, or flushing, advising them to seek immediate assistance.

3. Acute pain Related to: Inflammation, Tissue necrosis As evidenced by: Verbalization of pain, Tenderness with palpation, Guarding behaviors, Facial grimacing, Increased vital signs.

   Acute Pain Intervention

   1. Reposition the patient as needed to alleviate pressure on pain receptors.

   2. Administer prescribed pain medication. Mild to moderate pain can be managed with NSAIDs. Severe pain or pain related to procedures might require oral or IV opioids.

   3. Elevate or immobilize the affected site to improve circulation and reduce pain.

   4. Collaborate with physical and occupational therapists for pain management techniques.

   5. Be prepared to refer patients to a pain specialist, as osteomyelitis treatment can be prolonged and painful, potentially leading to chronic pain.

Complications

• Necrosis (tissue death)

• Gangrene (severe tissue death)

• Amputation (surgical removal of a limb)

• Sepsis (a life-threatening response to infection)

• Bone cancer.