From the Guidelines
Plain X-rays can show several findings suggestive of osteomyelitis in the foot, including soft tissue swelling, periosteal reaction, cortical erosion, and focal bone destruction or lucency, with characteristic findings being highly suggestive of osteomyelitis when interpreted by an experienced reader 1. The classic radiographic signs of osteomyelitis on a plain foot X-ray include:
- Soft tissue swelling
- Periosteal reaction
- Cortical erosion
- Focal bone destruction or lucency As osteomyelitis progresses, other changes may become visible, such as:
- Sequestration (segments of dead bone separated from living bone)
- Involucrum (new bone formation around dead bone)
- Joint space narrowing if the infection extends to adjacent joints These changes typically become visible only after 10-14 days of infection, as 30-50% of bone mineral content must be lost before changes are detectable on plain radiographs 1. The sensitivity of X-rays for early diagnosis of osteomyelitis is limited, ranging from 43-75%, with specificity around 75% 1. For this reason, more advanced imaging such as MRI, nuclear medicine studies, or CT may be necessary when osteomyelitis is clinically suspected but X-rays appear normal 1. When interpreting foot X-rays, it's essential to compare with the contralateral foot and consider clinical context, as similar findings can occur in neuropathic arthropathy (Charcot foot), particularly in diabetic patients 1. In cases where the initial X-ray is normal but clinical suspicion of osteomyelitis remains high, it may be useful to repeat the X-ray in 2-3 weeks to assess for any changes 1.
From the Research
Radiographic Findings of Osteomyelitis
The radiographic findings of osteomyelitis on a plain foot X-ray (X-ray) are not explicitly described in the provided studies. However, the following information can be gathered:
- Plain film radiography should be performed as initial imaging, but sensitivity is low in the early stages of disease 2, 3.
- The sensitivity of magnetic resonance imaging, both with and without contrast material, is higher for detecting areas of bone necrosis in advanced stages 2.
- Plain X-rays can reveal osteomyelitis, but the findings are not specified 4.
- The combination of probe-to-bone test and plain radiography can be sufficient for diagnosing osteomyelitis in high-risk inpatients, with a sensitivity of 0.97 and specificity of 0.92 5.
Key Points
- Osteomyelitis is an infection-related inflammatory disease of the bones 2.
- Imaging and laboratory results are typically used to support a clinical diagnosis of osteomyelitis 2, 3.
- Microbial cultures and bone biopsies provide conclusive diagnoses 2, 3.
- The first imaging procedure that needs to be done is radiography, but its sensitivity is low in the early stages of the disease 2, 3.