Osteomyelitis



Osteomyelitis


Julie Johnson

John R. Fowler



INTRODUCTION



  • Pathoanatomy—bony infection caused by microbial invasion characterized by inflammation and destruction of bone


  • Mechanism—contiguous spread (abscess, septic joint), direct inoculation (trauma, surgery, foreign body), or indirect (hematogenous seeding)


  • Epidemiology—24 cases per 100 000 person-years, more male patients than female, greater incidence with age, occurs more in lower extremity than in upper extremity, 1% to 6% of all hand infections involve bone, most often in the distal phalanx


  • Risk factors include recent surgery or trauma, IV drug use, immune deficiency/suppression, diabetes, vascular insufficiency.


EVALUATION



  • History—pain, fever, chills, fatigue, exposure to risk factors


  • Physical examination—tenderness, erythema, edema, warmth, fluctuance, exposed bone, sinus tract (Figure 50.1)


  • Laboratory studies—elevated white blood cell count, erythrocyte sedimentation rate, and C-reactive protein (lack specificity), positive blood cultures in 50% of cases; laboratory findings can be normal in osteomyelitis of the small bones of the hand and wrist


  • Imaging—Radiograph (Figure 50.2) (lytic lesion, surrounding sclerosis, periosteal thickening) may not show changes for 2 weeks, MRI positive up to 90% sensitivity and specificity (distinguish between soft tissue and bone infection), CT scan is rarely used in diagnosis (may be helpful for guided needle biopsy)




  • Classification—acute (within 2 weeks), subacute (between 2 weeks and several months), and chronic (after several months); 10% to 30% acute turn chronic; chronic osteomyelitis characterized by sequestrum (necrotic bone) and involucrum (new bone formation)






FIGURE 50.1 Abscess over thumb metacarpophalangeal joint tracks to bone with osteomyelitis.

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May 7, 2019 | Posted by in ORTHOPEDIC | Comments Off on Osteomyelitis
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