A 55-year-old diabetic man with peripheral vascular disease (ABI 0.4) has a non-healing below-knee gangrene. Transcutaneous oxygen pressure (TcPO2) at the proposed amputation site is 42 mmHg. What does this TcPO2 value indicate regarding healing potential?

• A TcPO2 <35 mmHg would be needed to predict poor healing; 42 mmHg is borderline
• B TcPO2 is unreliable in diabetic patients and ABI should be used instead
• C TcPO2 >40 mmHg predicts adequate tissue oxygenation and primary healing at this level ✓
• D TcPO2 >20 mmHg is sufficient to predict primary healing at any level

Explanation

Transcutaneous oxygen pressure (TcPO2) is the most reliable non-invasive predictor of amputation stump healing in vascular disease. A TcPO2 ≥40 mmHg at the proposed amputation level predicts reliable primary wound healing (sensitivity ~80%). TcPO2 <20 mmHg predicts healing failure. Values 20-40 mmHg are borderline — hyperbaric oxygen may be considered. This patient's TcPO2 of 42 mmHg at the below-knee level predicts adequate healing potential, supporting below-knee amputation rather than a higher level. ABI is unreliable in diabetics due to medial calcification causing falsely elevated readings.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.