Clin Med: Bone Infections

Osteomyelitis

An infection of bone tissue caused by pathogenic microorganisms invading the bone, leading to inflammation, vascular thrombosis, bone necrosis, and potential structural destruction.

Hematogenous Spread

A mechanism of infection where pathogens travel through the bloodstream to seed bone tissue; it represents the most common cause of osteomyelitis in children and most frequently affects the vertebrae in adults.

Contiguous Spread

An infection route resulting from the direct extension of bacteria from adjacent soft tissue, cellulitis, cutaneous ulcers, vascular insufficiency, or prior surgery.

Direct Inoculation

A pathway of infection resulting from trauma, penetrating injuries, open fractures, or direct surgical contamination of bone or joint structures.

Planktonic Bacteria

Free-floating bacteria that adhere to an inert substrate or matrix to initiate microcolony formation and biofilm development.

Biofilm

A structured community of bacteria embedded within a protective extracellular polymeric substance (exopolysaccharide), characterized by dormant subpopulations and reduced metabolic activity that confer resistance to antibiotic penetration and host defenses.

Sequestrum

A segment of devitalized, necrotic bone that has separated from viable surrounding bone tissue due to ischemia and localized bone abscess formation.

Involucrum

A sheath or collar of new, reactive bone formed by the periosteum surrounding necrotic bone tissue and sequestrum.

Cloaca

An opening or defect in the involucrum through which purulent exudate and necrotic debris drain away from infected bone.

Sinus Tract

A draining channel extending from deep infected bone to the external skin surface, pathognomonic for chronic osteomyelitis.

Brodie Abscess

A subacute or chronic intraosseous abscess presenting as a lucent, well-circumscribed lesion often surrounded by reactive sclerosis in the metaphysis of long bones.

Probe-to-Bone Test

A clinical bedside examination technique where a sterile, blunt metal probe is passed through a deep cutaneous or diabetic ulcer to detect palpable bone, indicating a high suspicion for underlying osteomyelitis.

Wagner Ulcer Classification

A grading scale used to evaluate the depth and severity of diabetic foot ulcers, ranging from Grade 0 (intact skin) to Grade 3 (deep ulcer with abscess, osteitis, or osteomyelitis) and Grade 5 (extensive foot gangrene requiring amputation).

Bone Biopsy and Culture

The definitive gold-standard diagnostic procedure for osteomyelitis, obtaining bone tissue for aerobic and anaerobic cultures and histopathology to identify the causative organism and direct antibiotic therapy.

Sequestrectomy

A surgical debridement procedure to excise and remove dead, necrotic bone (sequestrum) to eliminate the infectious nidus and promote tissue revascularization.

Septic Arthritis

An acute, purulent infection within a joint space leading to rapid synovial inflammation, cartilage destruction, and joint destruction, considered an orthopedic surgical emergency.

Arthrocentesis

The aspiration of synovial fluid from a joint space, serving as the essential and best initial diagnostic test for suspected septic arthritis as well as providing therapeutic decompression.

Synovial Fluid Leukocytosis

A laboratory finding on synovial fluid analysis characteristic of septic arthritis, typically presenting with an opaque/purulent appearance and a white blood cell count exceeding 50,000 cells/μL with marked neutrophil predominance.

Operative Irrigation and Debridement (I&D)

Urgent surgical exploration, flushing, and debridement of an infected joint performed to decompress intra-articular pressure, clear purulent fluid, and prevent irreversible articular cartilage erosion.

Nongonococcal Septic Arthritis

Bacterial joint infection most commonly caused by Staphylococcus aureus across all age groups (followed by Streptococci), which typically presents as an acute, warm, swollen, erythematous monoarthritis with restricted active and passive range of motion.

Gonococcal Septic Arthritis

Septic arthritis caused by Neisseria gonorrhoeae, which should be suspected in young, healthy, and sexually active individuals.

Erythrocyte Sedimentation Rate (ESR) & C-Reactive Protein (CRP)

Serum acute-phase inflammatory reactants that become elevated in bone and joint infections and are tracked serially to evaluate treatment efficacy and response.

Antibiotic Bone Beads

Polymethylmethacrylate (PMMA) or calcium sulfate beads impregnated with heat-stable antibiotics placed directly into debrided bone defects to deliver high local concentrations of antimicrobial therapy