Osteomyelitis in Emergency Medicine Workup

Updated: Nov 03, 2022
  • Author: Randall W King, MD, FACEP; Chief Editor: Jeter (Jay) Pritchard Taylor, III, MD  more...
  • Print

Approach Considerations

The studies below are indicated in patients with osteomyelitis.

The Infectious Diseases Society of America (IDSA) issued new guidelines on vertebral osteomyelitis in 2015. [11, 12]


Laboratory Studies

The studies below are indicated in patients with osteomyelitis.

CBC count

The WBC count may be elevated, but it is frequently normal.

A leftward shift is common with increased polymorphonuclear leukocyte counts.

C-reactive protein

The C-reactive protein level is usually elevated and nonspecific; this study may be more useful than the erythrocyte sedimentation rate (ESR) because it reveals elevation earlier.


The ESR is usually elevated (90%); however, this finding is clinically nonspecific.

CRP and ESR have limited roles in the setting of chronic osteomyelitis and are often normal.

Elevated ESR and CRP may suggest vertebral osteomyelitis. [11, 12]


Procalcitonin elevation: This can potentially be useful in diagnosis because it is relatively specific; however, it lacks sensitivity. [13]


Superficial wound or sinus tract cultures often do not correlate with the bacteria that is causing osteomyelitis and have limited use. Blood culture results are positive in approximately 50% of patients with hematogenous osteomyelitis. However, a positive blood culture may preclude the need for further invasive procedures to isolate the organism. Bone cultures from biopsy or aspiration have a diagnostic yield of approximately 77% across all studies. [2]


Imaging Studies


Radiographic evidence of acute osteomyelitis is first suggested by overlying soft-tissue edema at 3-5 days after infection. Examples of radiographic evidence of osteomyelitis are presented in the images below.

Osteomyelitis of the elbow. Photography by David E Osteomyelitis of the elbow. Photography by David Effron MD, FACEP.
Osteomyelitis of index finger metacarpal head seco Osteomyelitis of index finger metacarpal head secondary to clenched fist injury. Photography by David Effron MD, FACEP.
Osteomyelitis of the great toe. Photography by Dav Osteomyelitis of the great toe. Photography by David Effron MD, FACEP.
Osteomyelitis of T10 secondary to streptococcal di Osteomyelitis of T10 secondary to streptococcal disease. Photography by David Effron MD, FACEP.
Osteomyelitis. Radiography of diabetic foot showin Osteomyelitis. Radiography of diabetic foot showing osteomyelitis with gas. Photography by David Effron MD, FACEP.

Bony changes are not evident for 14-21 days and initially manifest as periosteal elevation followed by cortical or medullary lucencies. By 28 days, 90% of patients demonstrate some abnormality.

Approximately 40-50% focal bone loss is necessary to cause detectable lucency on plain films.

In patients in whom TB is of concern, chest radiography may demonstrate lesions characteristic of TB.

Plain radiographs of the spine are not sensitive for early diagnosis of vertebral osteomyelitis. [11, 12]


The MRI is effective in the early detection and surgical localization of osteomyelitis. [14, 15]

Studies have shown its superiority compared with plain radiography, CT, and radionuclide scanning and is considered to be the imaging of choice.

Sensitivity ranges from 90-100%.

Patients with back pain and with elevated ESR and CRP levels should undergo MRI to distinguish infection from disc herniation or other structural cause of back pain. [11, 12]

Positron emission tomographic scanning

Positron emission tomographic (PET) scanning has accuracy similar to MRI.

Radionuclide bone scanning

Three phase bone scan, gallium scan and tagged WBC scan are considerations in patients who are unable to have MRI imaging. A three phase bone scan has high sensitivity and specificity in adults with normal findings on radiograph. Specificity is dramatically decreased in the setting of previous surgery or traumatized bone.

In special circumstances, additional information can be obtained from further scanning with leukocytes labeled with gallium 67 and/or indium 111.

CT scanning

CT scans can depict abnormal calcification, ossification, and intracortical abnormalities.

It is not recommended for routine use for diagnosing osteomyelitis but is often the imaging of choice when MRI is not available


This simple and inexpensive technique has shown promise, particularly in children with acute osteomyelitis.

Ultrasonography may demonstrate changes as early as 1-2 days after onset of symptoms.

Abnormalities include soft tissue abscess or fluid collection and periosteal elevation.

Ultrasonography allows for ultrasound-guided aspiration.

It does not allow for evaluation of bone cortex.



The probe to bone (PTB) test may be a useful rapid adjunct in the evaluation of the diabetic foot. The procedure involves inserting a blunt probe into the suspected ulceration on the plantar surface of the foot. A "click" (solid or gritty end point) indicates a positive finding. Note that location of the ulcer and the performer’s expertise may affect reliability. [16] . A positive PTB test finding in a high-risk patient indicates a high probability of osteomyelitis. A negative PTB test result in a low-risk patient indicates a low probability of osteomyelitis. [17]