Cryotherapy Therapy is a medical technique both ancient and modern. As early as thousands of years ago, ice was used to treat infected wounds and various knife injuries. Ar-He knife, a kind of cryotherapy, is the first technique employing space rocket guidance technology in the world and the only technique with efficacies of ultra-low temperature and thermotherapy. Ar-He knife is a precise apparatus approved by the U.S. FDA for accurately targeting and killing cancer cells.