8-year-old with a non-healing wound on the leg (watch video)
Patient will present as → a 54-year-old male with fever, chills, and pain in the left foot. His symptoms progressively worsened over the course of a week. Medical history is significant for poorly controlled type II diabetes mellitus. On physical exam, there is tenderness to palpation of the left foot. Laboratory testing is significant for an elevated erythrocyte sedimentation rate and C-reactive protein; as well as, a leukocytosis. Plain radiograph demonstrates periosteal thickening and soft tissue swelling.
An acute or chronic infection and inflammation of the bone and bone marrow; can occur as a result of hematogenous seeding, a contiguous spread of infection, or direct inoculation into intact bone (trauma or surgery).
- Fever, restriction of movement of the involved extremity or refusal to bear weight, pain or tenderness in the infected area and signs of localized inflammation.
- In patients with diabetes, classic signs and symptoms of infection may be masked due to vascular disease and neuropathy.
- Staphylococcus auerus - most common cause overall.
- Pasteurella multocida - seen in cases caused by cat and dog bites.
- Salmonella spp. in patients with sickle cell.
- Mycobacterium tuberculosis - can also be seen in cases of vertebral involvement (Pott disease).
Routine radiography is standard 1st-line imaging
- Classic X-ray triad of demineralization, periosteal reaction, and bone destruction.
- Radiographic evidence of osteomyelitis lags behind symptoms and pathologic changes by 7 to 10 days.
- Magnetic resonance imaging (MRI) shows the changes before plain-film radiography or bone scan.
Labs: CRP is usually elevated but nonspecific. WBC and ESR are high in most cases.
- A persistently elevated CRP (4–6 weeks) can be associated with persistent osteomyelitis.
- Definitive diagnosis is made by blood cultures or by needle aspiration/bone biopsy.
Empiric therapy should be directed toward most probable organism and tailored once culture results are available. All hardware (if post-op) need to be removed
- Duration of therapy 4–6 weeks for acute osteomyelitis and generally >8 weeks for chronic osteomyelitis or MRSA infection.
- If a diabetic foot ulcer is larger than 2 x2 cm or bone is palpable osteomyelitis is likely.
Three-phase bone scan of the foot
A nuclear medicine bone scan may detect osteomyelitis much earlier than plain radiographs; however, it is relatively nonspecific and makes differentiating osteomyelitis from other pathologic conditions difficult.
Ultrasound of the great toe
Ultrasound has numerous benefits in detecting osteomyelitis, such as real-time imaging and avoidance of radiation and contrast dye. However, MRI is the preferred diagnostic modality because of its improved image quality and soft-tissue detail.
AP and lateral radiographs of the foot
Radiographs may show periosteal elevation and other signs suggestive of osteomyelitis; however, these signs may lag behind the disease onset by weeks and are not as reliable as MRI findings. However, radiographs should be the first imaging study ordered prior to an MRI.
MRI of the foot
CT scan of the foot
Although CT scans may show osseous changes of osteomyelitis earlier than plain radiographs; MRI is still the preferred modality for diagnosis due to its improved soft-tissue visualization.