What is the standard of care for postoperative evaluation of a patient with swelling on top of the foot after bunion surgery, particularly when diagnostic imaging (e.g. x-rays) is ordered but no laboratory tests (e.g. Complete Blood Count (CBC), Erythrocyte Sedimentation Rate (ESR)) are performed?

Standard of Care for Postoperative Evaluation of Swelling After Bunion Surgery

When a patient presents with swelling on top of the foot after bunion surgery, comprehensive evaluation must include both imaging AND laboratory tests to rule out infection, as relying on X-rays alone is inadequate and may lead to missed bone infections requiring amputation.

Proper Postoperative Evaluation Protocol

Initial Assessment

• Evaluate for classic signs of infection: erythema, warmth, tenderness, pain, or induration 1
• Document wound characteristics including:
  • Size and extent of swelling
  • Quality and quantity of any drainage
  • Percentage of necrotic tissue, slough, or granulation tissue 2
  • Temperature difference between affected and unaffected foot

Diagnostic Testing

1. Imaging Studies:

   • Plain X-rays are appropriate as first-line imaging but are insensitive to early osteomyelitis 1
   • X-rays alone are insufficient to rule out bone infection

2. Laboratory Tests (Required):

   • Complete blood count (CBC)
   • Inflammatory markers:
     • Erythrocyte sedimentation rate (ESR) - values ≥70 mm/hr suggest osteomyelitis 1
     • C-reactive protein (CRP) - values ≥80 mg/L with elevated ESR have high positive predictive value 1
     • Procalcitonin (PCT) - values ≥0.33 ng/mL have highest diagnostic accuracy 1

3. Advanced Imaging (when infection is suspected):

   • MRI is the preferred advanced imaging when osteomyelitis remains in doubt despite X-rays and laboratory findings (Strong recommendation, Moderate evidence) 1
   • CT scan with IV contrast is an appropriate alternative if MRI is contraindicated 1

Wound Assessment

• Probe-to-bone test: Using a sterile blunt metal probe to detect bone contact (sensitivity 87%, specificity 83%) 1
• Document any sinus tracts, undermining, or tunneling 2

Red Flags Requiring Immediate Action

• Persistent swelling despite standard postoperative care
• Increasing pain rather than decreasing pain over time
• Drainage from the surgical site
• Elevated inflammatory markers
• Fever or systemic symptoms

Common Pitfalls to Avoid

1. Relying solely on X-rays: Plain radiographs are insensitive to early osteomyelitis and may appear normal despite active infection 1

2. Failure to obtain laboratory tests: Inflammatory markers are essential for diagnosing bone infection and should be obtained when postoperative swelling is concerning 1

3. Delayed advanced imaging: When infection is suspected but X-rays are normal, MRI should be promptly obtained 1

4. Misattributing swelling to normal postoperative changes: Persistent or worsening swelling requires thorough investigation rather than reassurance alone

5. Inadequate documentation: Standardized wound measurement and documentation are essential for tracking progression 2

When to Suspect Osteomyelitis

• Persistent swelling beyond expected postoperative timeline
• Probe-to-bone test is positive
• Elevated inflammatory markers (ESR ≥70 mm/hr, CRP ≥80 mg/L)
• Radiographic changes including:
  • Loss of bone cortex with bony erosion
  • Focal loss of trabecular pattern
  • Periosteal reaction or elevation 1

Following these guidelines ensures proper evaluation of postoperative swelling after bunion surgery and helps prevent devastating complications like bone infection requiring amputation.