Dr. Chatterjee presented a great noon report where a middle-age male presented in DKA secondary to osteomyelitis.
Classification of Osteomyelitis
Osteomyelitis can be classified by how it occurs and timeline.
Osteomyelitis can either be acute or chronic:
Acute osteomyelitis- This is defined as the symptom duration of few days or weeks. In acute osteomyelitis, sequestra are absent
Chronic osteomyelitis is a long-standing infection over months or years. The presence of sinus tract is pathognomonic for chronic osteomyelitis. Here, sequestra are present due to bone ischemia and necrosis.
Acute and chronic osteomyelitis can present differently. Acute osteomyelitis can present as pain at involved site, with or without movement. Local findings and systemic symptoms may be present. Chronic osteomyelitis often presents with pain, erythema, or swelling, but usually not fever. There are intermittent flares of pain and swelling usually.
Osteomyelitis is also classified by how it is spread:
Hematogenous- accounts for 20% of cases, most commonly in the vertebral column. In IV drug users, bugs are more likely to infect the sternoclavicular & sacroiliac bones. Other frequent etiologies include intravascular catheters, infective endocarditis, and distant foci of infection. While monomicrobial infection by S. aureus is the most common, remember that Salmonella is common in patients with Hemoglobin SS disease and IV drug users can also have infection with Pseudomonas aeruginosa.
Direct Inoculation- More common in younger patients, this tends to occur with either trauma or surgery.
Spread from adjacent tissues- This is more common in older adults. Risk factors include poorly healing soft tissue wounds, presence of orthopedic hardware, diabetes, PVD, peripheral neuropathy.
Complications of osteomyelitis include sinus tract formation, contiguous soft tissue infection, abscesses, septic arthritis, systemic infection, bony deformity, fracture, and malignancy.
Diagnosis
Consider nonhematogenous osteomyelitis in the setting of new or worsening MSK pain, especially in:
Patients with poorly healing soft tissue or surgical wounds adjacent to bony structures
Cellulitis overlying previously implanted orthopedic hardware
Patients with traumatic injury
Diabetic patients with ulcers that probe to bone.
Consider hematogenous osteomyelitis in the setting of new or worsening MSK pain, especially with fever and recent bacteremia.
The gold standard for diagnosis is culture obtained from biopsy of involved bone. You want to obtain two specimens: 1 for gram stain and culture, 1 for histopathology.
Treatment
For nonhematogenous osteomyelitis, treatment focuses on operative debridement followed by antimicrobial therapy.
If residual infected bone is present, the patient will require a prolonged duration of IV or highly bioavailable oral antibiotics. While the optimal therapy duration is uncertain, this is usually six weeks, until debrided bone has been covered by vascularized tissue.
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