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Question
52 year-old male with diabetes complains of severe left foot pain for one month and now inability to ambulate. Vital signs are normal and X-rays are shown below. What's the diagnosis and why should you get a biopsy early?
Answer
Answer: Osteomyelitis and a bone biopsy (with culture) should be obtained early and before starting antibiotics.
Osteomyelitis is inflammation of a bone secondary to an infecting organism.
Risk factors include:
- Injury to bone from surgery or trauma
- Spread via bacteremia or overlying skin infection
- Secondary to foreign body or prosthetics
Causative bacteria typically include S. Aureus, Pseudomonas, Salmonella (classically with Sickle cell)
Diagnosis
- X-ray may be used (periosteal or cortical changes) but lacks sensitivity; abnormalities may not be evident for up to 14 days
- Bone scan is a better test, but false positives may occur with overlying skin infections
- MRI is arguably the best test; delineates tissues planes and the extent of infection
Early and long-term antibiotic treatment (4-6 weeks) is required, but should be done AFTER obtaining bone biopsy and culture; long-term antibiotics are the rule and the most narrow spectrum antibiotic should be determined.
Operative management is sometimes required; especially if secondary to infected prosthetics.
References
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