They are usually preceded by callus formation. There is evidence of sensory neuropathy on examination, and the tissue generally looks healthy and non-ischemic. Arterial pulses in the foot are usually good in the primarily neuropathic ulcer. Black eschar is not typically present. The extent of the ulcer may be hidden by the surrounding callus, and these lesions require careful debridement for accurate bedside assessment.
Crepitation indicates a deep necrotizing process, and flucutance suggests localized suppuration.