Diagnosis

Obtain deep wound culture after cleaning and debriding wound. Superficial culture results correlate poorly with true pathogen

If probing the ulcer base goes directly to bone, this is highly suggestive of osteomyelitis. Obtain a plain X-ray. Further imaging is usually unnecessary except when required for surgical planning

Assessment for peripheral arterial disease should be done for every diabetic with a foot ulcer. If dorsalis pedis or posterior tibialis pulses are not easily palpated, ankle-brachial index (ABI) and toe pressures should be done (if not done in past 12 months):

  • ABI <0.9 is abnormal. Consider vascular imaging and referral to vascular surgeon.
  • Toe pressure <30 mmHg is highly correlated to failure of medical management alone. Consider urgent vascular imaging and referral to vascular surgeon

Imaging

Plain X-ray of the involved area should be done as baseline

MRI is the most sensitive and specific imaging modality to diagnose soft-tissue complications or osteomyelitis

Bone scan is helpful to rule out osteomyelitis if negative, but a positive result is not specific. False negatives may be seen in severe peripheral arterial disease. It can be combined with SPECT/CT to provide better three-dimensional localization

White blood cell-labelled radionuclide scan has good performance to detect osteomyelitis. It can be combined with SPECT/CT to provide better three-dimensional localization