A 60-year-old diabetic patient presents with a plantar foot ulcer under the first metatarsal head that probes to bone. X-ray shows periosteal reaction and cortical erosion of the metatarsal head. The most important investigation to confirm osteomyelitis underlying this ulcer is:
- A MRI of the foot with gadolinium contrast ✓
- B Tc-99m bone scan (triple phase)
- C Serum CRP and ESR measurement
- D Doppler ultrasound for vascular status
Explanation
MRI with gadolinium is the gold standard investigation for diagnosing diabetic foot osteomyelitis, with sensitivity ~90% and specificity ~80%. It distinguishes osteomyelitis (marrow edema, cortical destruction, periosteal enhancement) from Charcot neuroarthropathy, soft tissue infection, and non-infected bone. Tc-99m bone scan is sensitive but not specific in diabetes (Charcot mimics osteomyelitis on bone scan). CRP/ESR are non-specific. Doppler assesses vascular status (important for healing) but cannot diagnose osteomyelitis. The 'probe-to-bone' test is highly specific clinically, but MRI provides anatomic detail for surgical planning.
Reference: Maheshwari Essential Orthopaedics, 6th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.