From the Guidelines
Osteomyelitis can be visible on X-ray, but only after significant bone destruction has occurred, typically 10-14 days after the infection begins, with a sensitivity of 43-75% and specificity of 75-83%. According to the 2016 IWGDF guidance on the diagnosis and management of foot infections in persons with diabetes 1, a probable diagnosis of bone infection is reasonable if there are positive results on a combination of diagnostic tests, such as probe-to-bone, serum inflammatory markers, plain X-ray, MRI, or radionuclide scanning. The 2012 Infectious Diseases Society of America clinical practice guideline for the diagnosis and treatment of diabetic foot infections also recommends plain radiographs of the affected foot to look for bony abnormalities, as well as for soft tissue gas and radio-opaque foreign bodies 1.
Some key points to consider when interpreting X-ray results for osteomyelitis include:
- Early signs of osteomyelitis on X-ray may include soft tissue swelling and deep tissue swelling
- Later findings may include periosteal reaction, bone destruction, and sequestration (dead bone fragments)
- X-rays have limited sensitivity and specificity for detecting osteomyelitis, especially in the early stages of infection
- Additional imaging modalities like MRI, CT scan, or nuclear medicine studies may be needed for accurate diagnosis, especially in early infection
It's essential to note that negative X-ray results do not exclude osteomyelitis if clinical suspicion is high, and further imaging or diagnostic tests may be necessary to confirm the diagnosis. The IWGDF guidance recommends using MRI when an advanced imaging test is needed for diagnosing diabetic foot osteomyelitis 1.
From the Research
Osteomyelitis Diagnosis using X-ray
- Osteomyelitis is an infection-related inflammatory disease of the bones, and imaging results are crucial for its diagnosis 2.
- The first imaging procedure used is radiography, but its sensitivity is low in the early stages of the disease 2.
- Conventional radiography should always be the first imaging modality used, as it provides an overview of the anatomy and the pathologic conditions of the bone and soft tissues of the region of interest 3.
- However, conventional radiography and computed tomography (CT) imaging may not be sensitive enough to detect early acute osteomyelitis, even after a week of symptoms in the affected limb 4.
Limitations of X-ray in Osteomyelitis Diagnosis
- The sensitivity of X-ray is low in the early stages of osteomyelitis, making it challenging to diagnose the condition using this modality alone 2, 3.
- Other imaging modalities like magnetic resonance imaging (MRI) are more sensitive and specific for detecting osteomyelitis, especially in the early stages 3, 4.
- MRI is the imaging modality of choice for diagnosing osteomyelitis, particularly in cases where conventional radiography and CT imaging are inconclusive 4.
Alternative Imaging Modalities
- MRI is the most sensitive and specific imaging modality for detecting osteomyelitis, providing superb anatomic detail and accurate information about the extent of the infectious process and soft tissues involved 3, 4.
- Other imaging modalities like ultrasonography, computed tomography, and scintigraphy may also be used to diagnose osteomyelitis, but MRI is generally considered the gold standard 3.