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▪ Bacterial invasion and destruction of bone
▫ E.g. Staphylococcus aureus (S. aureus),
Mycobacterium tuberculosis (M.
tuberculosis), Pseudomonas aeruginosa
▪ Trauma/open fractures, diabetes/
atherosclerosis, orthopedic implants,
▪ Pain → individual avoids using infected
▪ Fever, chills, weakness, headache
▪ Needle aspiration: pathogen detection
▪ Before identifying pathogen → general
▪ Known pathogen → specifi c antibiotics
Figure 106.1 An X-ray image of the tibia
demonstrating a radiolucency with a sclerotic
border consistent with a Brodie abscess.
▪ Bacterial infection (S. aureus, M.
tuberculosis most common) → bone, bone
▪ Bacteria → bone via bloodstream, nearby
infection, open fractures/orthopedic
▪ First week: bacterial reproduction →
infl ammation → bone necrosis (e.g.
sequestrum); if periosteum bursts →
▪ Later: cytokines induce bone resorption
→ replacement with fi brous tissue → new
bone formation around necrotic one (e.g.
▪ Diabetes, fractures, splenectomy,
orthopedic procedures/hardware
▪ If M. tuberculosis disseminates from joint to
▪ Inadequate treatment → chronic infection
▪ Redness, swelling, painful site, sinus
▪ Weakness, fever, headache, shivering
▪ Contrast enhancement of abscess rim
▪ If MRI not attainable: higher radiotracer
▫ Osteopenia (decreased bone density)
▫ Periosteal reaction (thickening of
▫ Aggressive infection → Codman’s
triangle (lifted periosteum with triangleshaped, ossifi ed edge)
Chapter 106 Bone & Joint Infections
Figure 106.2 A plain radiograph of the right
lower leg of an individual with postoperative
osteomyelitis. The surgical wound started
discharging pus two weeks post open
reduction. There is medial cortical destruction
and loss of trabeculations with lateral cortical
▪ Long-term intravenous antibiotics
▪ Surgical removal of dead bone
▪ Joint structures: infected, damaged
▪ Pathogen enters the joint via bloodstream,
from nearby infection/directly (e.g. open
▪ Infection of joint → endotoxin production →
cytokine release → neutrophil attraction →
infl ammation, damage of joint structures
▪ Most commonly S. aureus (any age group),
Neisseria gonorrhoeae (N. gonorrhoeae;
▪ Most commonly affects knee; less
▫ Endosteal scalloping (focal resorption of
▫ Advanced osteomyelitis → cortical bone
▫ Peripheral sclerosis (increased density
at periphery, lower density centrally)
Needle aspiration guided with ultrasound
▪ Specifi c antibiotic therapy
▪ Artifi cial joint, surgical procedure
▪ Chronic arthritis (e.g. rheumatoid arthritis)
Figure 106.3 A red, hot, swollen left knee in
an individual with septic arthritis.
▪ General antibiotics depending on Gram
▪ Switch to specifi c antibiotics once bacteria
▪ Pain medications (e.g. NSAIDs,
▪ Surgically drain, cleanse joint fl uid
▪ ↑ fl uid in synovial part of joint
▪ Narrowing of joint space due to destruction
▪ Destruction of bone adjacent to cartilage
▪ Assess spread of infection outside the joint
▪ Guiding needle for aspiration
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