Definition
- Frostbite is tissue freezing with ice crystal formation, followed by microvascular thrombosis on rewarming.
- Raynaud phenomenon is episodic digital pallor, cyanosis, then rubor, triggered by cold or stress.
- Buerger disease (thromboangiitis obliterans) affects small and medium vessels in young smokers.
Classification
- Frostbite degrees run from first (hyperaemia) and second (clear blisters) to third (haemorrhagic blisters) and fourth (necrosis into bone).
- Cauchy classification grades 1 to 4 by extent of cyanosis at presentation, from none to carpal level.
- ANCA associated vasculitis includes granulomatosis with polyangiitis, microscopic polyangiitis and eosinophilic granulomatosis with polyangiitis.
Investigations
- Allen test assesses radial and ulnar contribution to the palmar arches. Delayed refill indicates occlusion or an incompetent arch.
- Angiography of Buerger disease shows corkscrew collaterals and distal segmental occlusions.
- Nailfold capillaroscopy, ANA, anti-centromere and anti-Scl-70 antibodies, and ANCA define secondary causes.
- Technetium bone scan or MR angiography after frostbite predicts the demarcation line.
Management
- Frostbite rewarming uses a water bath at 37 to 39°C until the part is pliable and flushed.
- Avoid rewarming if refreezing is likely. Thawing then refreezing causes greater damage.
- Give ibuprofen and tetanus cover. Debride clear blisters and leave haemorrhagic blisters intact.
- Consider intravenous tPA within 24 hours of rewarming for severe frostbite with perfusion deficit on imaging.
- Iloprost, a prostacyclin analogue, is used for severe frostbite, including when tPA is contraindicated.
- Delay amputation until demarcation, which can take up to three months, with dry mummified tissue left in place.
- Early surgery is reserved for infection, wet gangrene or compartment syndrome.
- Raynaud treatment is cold avoidance, then nifedipine or topical nitrates.
- Buerger disease requires complete smoking cessation to halt progression.
- Digital periarterial sympathectomy strips adventitia from the common digital arteries and superficial palmar arch for refractory ischaemia or ulcers.
- Hypothenar hammer syndrome is ulnar artery thrombosis at the hook of hamate, treated by resection and vein graft.
Complications
- Cold intolerance, hyperhidrosis and neuropathic pain persist after frostbite.
- Digital ulceration, gangrene and calcinosis complicate scleroderma.
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 12 October 2026.