Snapshot A 52-year-old man presents to the emergency department for fever, chills, and pain in the left foot. His symptoms progessively worsened over the course of a week. Medical history is significant for poorly controlled type II diabetes mellitus. On physical exam, there is tenderness to palpation of the left foot. Laboratory testing is significant for an elevated erythrocyte sedimentation rate and C-reactive protein; as well as, a leukocytosis. A plain radiograph demonstrates periosteal thickening and soft tissue swelling. Introduction Clinical definition inflammation of the bone and bone marrow most commonly due secondarily to infection that can be categorized as acute osteomyelitis more common in children typically symptom onset is within 2 weeks postinfection chronic osteomyelitis more common in adults typically symptoms persists months or years postinfection Epidemiology risk factors diabetes peripheral vascular disease open fracture intravenous drug use catheter use surgery Etiology note that infection can be due to bacteria, fungi, and mycobacteria microbiology Staphylococcus auerus most common cause overall may be seen in sickle cell disease prosthetic joint replacement vertebral involvement intravenous drug use Neisseria gonorrhoeae rare Staphylococcus epidermidis can also be seen in prosthetic joint involvement Mycobacterium tuberculosis can also be seen in cases of vertebral involvement (Pott disease) Pasteurella multocida seen in cases caused by cat and dog bites Pseudomonas and Candida can also be seen in cases caused by intravenous drug abuse Pathogenesis hematogenous seeding of bone contiguous spread of infection from adjacent structures (e.g., soft tissues and joints) direct inoculation e.g., penetrating trauma and contaminated surgical tools Prognosis mortality has significantly decreased since the use of antibiotics Presentation Symptoms acute osteomyelitis lethargy acute pain in affected site erythema and chronic osteomyelitis chronic pain Physical exam swelling erythema tenderness reduced range of motion bone tenderness ulcers exposed bone may be seen sinus tract pathognomonic for chronic osteomyelitis must perform a neurovascular exam Imaging Radiographs indication preferred initial test in evaluating for osteomyelitis note that it takes 10-14 days postinfection for findings to appear findings periosteal thickening and elevation "Codman triangle" Magnetic resonance imaging indication considered when radiography is unrevealing findigs may reveal bone necrosis, abscess, and sinus tracts Studies Labs ↑ C-reactive protein ↑ erythrocyte sedimentation rate leukocytosis present in acute osteomyelitis unlikely to be found in chronic osteomyelitis Biopsy and culture confirms the diagnosis Differential Septic arthritis Gout Cellulitis Osteosarcoma Treatment Medical empiric antibiotics indication considered the mainstay of treatment eventually tailored to organism after culture sensitivities return Operative debridement indication to remove necrotic tissue Complications Bone necrosis Sepsis Squamous cell carcinoma most common tumor associated with osteomyelitis