Osteomyelitis

Posted by e-Medical PPT Wednesday, August 29, 2012
Inflammation of bone and marrow
Types 
Pyogenic osteomyelitis
Tuberculous osteomyelitis


Pyogenic osteomyelitis
Always caused by bacteria
Routes of infection
 Hematogenous spread
 Extension from a contiguous site
 Direct implantation

Causes
Staphylococcus aureus in 80% to 90% of cases
E.coli, Pseudomonas, and Klebsiella in patients with genitourinary tract infections and IV drug abusers.
In neonates: Hemophilus influenza and group B streptococci
In patients with sickle cell disease –Salmonella infection

Pathophysiology
1.Organisms once localized in bone
2.Bacteria proliferate and induce inflammatory reaction and cause cell death.
3.Bone undergoes necrosis within first 48 hours
4.Bacteria and inflammation spread within the shaft of the bone and may percolate throughout the haversian systems and reach the periosteum
5.Subperiosteal abscess
6.Segmental bone necrosis----> sequestrum (dead piece of bone)
7.Rupture of periosteum leads to an abscess in the surrounding soft tissue and the formation of draining sinus.
8.Over time, host response develops
9.After first week of infection chronic inflammatory cells become more numerous
10.Cytokines from leukocytes stimulates osteoclastic bone resorption ingrowth of fibrous tissue deposition of reactive bone in the periphery
11.Reactive woven or lamellar bone which forms sleeve of living tissue surrounding dead bone is called as involucrum.

Brodie abscess: is a small intraosseous abscess that frequently involves the cortex and is walled off by reactive bone
Sclerosing osteomyelitis of Garre: typically develops in jaw and is associated with extensive new bone formation 
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