Chapter 26: Bone Infections Flashcards
Common pathogens causing osteomyelitis include…
Staph, E. Coli, Neisseria gonorrhoeae, Haemophilus influenzae, and Salmonella.
Hematogenous osteomyelitis most commonly affects the…
Metaphyses of long bones. This is due to unique vascular supply of the region. Loop allows slowing and sludging of blood flow - bacteria penetrate vessel wall.
Pressures thin-walled vessels -> compromises vascular supply -> necrosis, abscess, and pus formation.
A hole formed in the bone during the formation of a draining sinus.
Cloaca
A fragment of necrotic bone embedded in pus.
Sequestrum.
Reactive bone from periosteum and endosteum that surrounds and contains a bone infection.
Brodie abscess
Periosteal new bone formation forms a sheath around necrotic sequestrum. May exist for years before medical attention is sought.
Involucrum.
Why does osteomyelitis travel between vertebral bodies so easily?
Intervertebral disk is not a barrier to bacterial osteomyelitis, especially staph.
IV drug use, upper UTIs, urologic procedures, hematogenous spread. Common involvement of vertebrae in adults.
Complications of osteomyelitis include…
Septicemia
Acute bacterial arthritis (joint inflammation, digestion of cartilage. Destruction of articular cartilage. Medical emergency.)
Pathologic fractures
Squamous cell carcinoma (chronic osteomyelitis)
Amyloidosis
Chronic osteomyhelitis - difficult to treat, antibiotics don’t reach.
A child with a history of tuberculosis presents with back pain.
Below is the biopsy. What is the disease?
Tuberculous spondylitis (Pott Disease)
Granulomas produce caseous necrosis of the bone marrow. Kyphosis and scoliosis result from vertebrae collapse (little reactive bone formation).
Intervertebral disks not invaded by bacteria. Crushed by compression fractures instead.
If rupture into soft tissue anteriorly, drain along spinal ligaments and form cold abscess.
Psoas abscess forms near lumbar vertebrae and dissects along the pelvis as a draining sinus.
Paraplegia may result.
Granulomas in synvial tissue, which become edematous and papillary and fill the joint space. Massive destruction of articular cartilage.
Destroyed joint is replaced by bone.
Tuberculous arthritis.
Results in bony ankylosis.
The most common site of tuberculous osteomyelitis of the long bones is…
The greater trochanter of the femur.
A child presents with a functionless limb. Biopsy shows spirochetes in the epiphysis and periosteum.
Bones appear short and deformed, and the cone of calcified cartilage is destroyed. The cortex is thickened.
Biopsy shown below demonstrates periosteal new bone formation and medullary cavity filled with lymphoplasmacytic infiltrate.
Congenital syphilis of bone
Funcitonless limb called pseudoparalysis of Parrot
An adult presents with bone lesions. He reports past history of a chancre followed by several wartlike lesions on the genitals.
Biopsy demonstrates periostitis and gumma formation. Bone adjacent to gummas replaced by fibrous marrow. Periosteum is irregular and thickened, perforated by pits and serpingous ulkcerations.
Lysis and collapse of nasal and palatal bones is seen.
Acquired syphilis of bone. Seen in tertiary stage.
Saddle nose.
Punched-out lytic defects of bone are discovered with collections of large, phagocytic cells with pale, eosinophilic cytoplasm and convoluted or grooved nuclei.
Electron microscopy reveals racquet-shaped tubular structures.
Many eosinophils fill the lesions, as well as multinucleated osteoclastic giant cells.
Langerhans cell histiocytosis.
Characterized by birbeck granules on electron microscopy
A langerhans cell histiocytosis typically involving one or two lytic areas of bone in axial or appendicular skeleton.
Mild pain or incidental findings. May have some pathologic fractures, but eventual recovery is normal.
Eosinophilic granuloma.
