Osteomyelitis 

          (Broadies Abscess)

          (Pott's disease). tuberculous osteomyelitis

 
Definition
 Inflammation of the bone marrow and adjacent bone.
 
Clinical Description

Acute hematogenous osteomyelitis occurs predominantly in children, with the metaphysis of long bones the most common location. Patients usually present within several days to one week after the onset of symptoms. In addition to local signs of inflammation and infection, patients have signs of systemic illness, including fever, irritability and lethargy. Typical clinical findings include tenderness over the involved bone and decreased range of motion in adjacent joints. The diagnosis of acute osteomyelitis can be established based on several specific clinical findings

The subacute and chronic forms of osteomyelitis usually occur in adults. Generally, these bone infections are secondary to an open wound, most often an open injury to bone and surrounding soft tissue. Localized bone pain, erythema and drainage around the affected area are frequently present. The cardinal signs of subacute and chronic osteomyelitis include draining sinus tracts, deformity, instability and local signs of impaired vascularity, range of motion and neurologic status. The incidence of deep musculoskeletal infection from open fractures has been reported to be as high as 23 percent.6 Patient factors, such as altered neutrophil defense, humoral immunity and cell-mediated immunity, can increase the risk of osteomyelitis

Radiology & Imaging
In osteomyelitis of the extremities, plain-film radiography and bone scintigraphy remain the primary investigative tools8,9 (Table 4).9 Radiographic evidence of bone destruction by osteomyelitis may not appear until approximately two weeks after the onset of infection (Figure 1). The radiographs may reveal osteolysis, periosteal reaction and sequestra (segments of necrotic bone separated from living bone by granulation tissue).10 A bone abscess found during the subacute or chronic stage of hematogenous osteomyelitis is known as a Brodie's abscess.

For nuclear imaging, technetium Tc-99m methylene diphosphonate is the radiopharmaceutical agent of choice11 (Figure 2). The specificity of bone scintigraphy will not be high enough to confirm the diagnosis of osteomyelitis in many clinical situations.12 On a bone scan, osteomyelitis often cannot be distinguished from a soft tissue infection, a neurotrophic lesion, gout, degenerative joint disease, postsurgical changes, a healing fra cture, a noninfectious inflammatory reaction or a stress fracture. In many instances, a bone scan will be positive despite the absence of bone or joint abnormality.

Magnetic resonance imaging (MRI) can be extremely helpful in unclear situations (Figure 3). This imaging modality is particularly useful when a patient is suspected of having osteomyelitis, discitis or septic arthritis involv ing the axial skeleton and pelvis. Compared with bone scintigraphy, MRI has equivalent or greater sensitivity, specificity and accuracy for the detection of osteomyelitis. MRI also provides greater spatial resolution in delineating the anatomic extension of infection.13

Ultrasonography and computed tomographic (CT) scanning may be helpful in the evaluation of suspected osteomyelitis.10 An ultrasound examination can detect fluid collections (e.g., an abscess) and surface abnormalities of bone (e.g., periostitis), whereas the CT scan can reveal small areas of osteolysis in cortical bone, small foci of gas and minute foreign bodies.

 
Pathology
 Acute osteomyelitis is the clinical term for a new infection in bone. This infection occurs predominantly in children and is often seeded hematogenously. In adults, osteomyelitis is usually a subacute or chronic infection that develops secondary to an open injury to bone and surrounding soft tissue. The specific organism isolated in bacterial osteomyelitis is often associated with the age of the patient or a common clinical scenario (i.e., trauma or recent surgery). Staphylococcus aureus is implicated in most patients with acute hematogenous osteomyelitis. Staphylococcus epidermidis, S. aureus, Pseudomonas aeruginosa, Serratia marcescens and Escherichia coli are commonly isolated in patients with chronic osteomyelitis

Other Possible causitive organisms

  • pyogenic (Staph. aureus)
  • TB
  • syphilis
  • Salmonella (hemoglobinopathy,

Diabetes Mellitus
Diabetes is a significant contributing factor in osteomyelitis, particularly when patients have concomitant neurologic or vascular abnormalities.33 A wide variety of organisms (e.g., P. aeruginosa, staphylococci, anaerobes) are frequently isolated from these infections. Initial hospitalization to assess vascular supply, identify offending microbes, remove dead tissue, drain wounds and assure compliance may be necessary.

 
Treatment:
For optimal results, antibiotic therapy must be started early, with antimicrobial agents administered parenterally for at least four to six weeks. Treatment generally involves evaluation, staging, determination of microbial etiology and susceptibilities, antimicrobial therapy and, if necessary, debridement, dead-space management and stabilization of bone.
This condition can be difficult to treat, since bone is not highly vascular, so high antibiotic concentrations can be difficult to attain.

Treatment for open wound / abscess - open abscess, curette, pack with bone chips
Prognosis: excellent after tx
 
Images

http://www.health.auckland.ac.nz

RNI Study of Osteomyelitis of the great toe

MRI Study Pott's disease). tuberculous osteomyelitis
 

 

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