Predicting Amputation In Frostbite



Posted by Jeremy Windsor on Nov 15, 2018

Following the death of Manu Cauchy earlier this year, STDZ are celebrating his life with a series of posts that describe some of his most important scientific contributions. Here's the first...

In 2001, Manu Cauchy and his colleagues at Chamonix Hospital described for the first time a method to accurately identify those who need amputation after a frostbite injury. We all know this is particularly useful in frostbite as surgery is often delayed for several weeks or months in order for injuries to heal. As Manu so memorably wrote, this delay, "often causes mental anguish for patients".

Cauchy and his team set about predicting the need for amputation by reviewing the records of 70 patients and 494 frostbitten digits. The first step was to establish a link between the extent of injury and the need for surgery. This was most clearly seen at the ends of the spectrum - frostbite to the distal phalanx recovered spontaneously, whilst the vast majority of those with metacarpal / metatarsal (98-100%) or carpal / tarsal (100%) injuries needed surgery. However the results of the study were unable to accurately predict the need for surgery in those with middle and proximal phalanges injury. In these two groups the likelihood of surgery varied from 23 to 83% depending upon whether toes or fingers were involved. The solution lay in technology. Cauchy had shown in earlier work that an isotope bone scan (2 phase 99mTc-HMTP) conducted within 3 to 8 days of injury was able to accurately predict whether a digit would heal spontaneously and if not, the level of amputation that would be needed. This led Cauchy and his team to devise a classification system that is now widely used:


Grade 1 - minimal injury with no evidence of damage after rewarming

No bone scan required - No long term sequelae


Grade 2 - injury to distal phalanx visible after rewarming - blisters visible

No bone scan required - Nail damage only 


Grade 3 - injury to proximal and middle phalanges after rewarming - haemorrhagic blisters visible

Bone scan required. Radio tracer uptake determines likelihood of spontaneous healing and extent of surgery 


Grade 4 - injury to metacarpal / metatarsal and carpal / tarsal after rewarming - haemorrhagic blisters visible

Bone scan required. Radio tracer uptake determines likelihood of spontaneous healing and extent of surgery

High risk of infection and systemic involvement


All of the images were taken from Cauchy's study published in the Wilderness and Environmental Medicine. 

This can be found at:

https://www.wemjournal.org/art...


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