English to Polish Medical Other Surgery

Older surgeons preferred the circular method, which involved making a sweeping incision around the circumference of the limb, pulling away the skin and muscle, and sawing through the bone. This called for a heavy knife with a curved, broad blade. Later generations, however, preferred what they called the flap method. Liston performed the flap method on the etherized Churchill in 1846. By the 1820s, the amputation knife was already thinner and lighter, with a straight blade reflecting the growing popularity of this technique. It involved “transfixing,” which essentially required the surgeon to stab the patient, pushing the amputation knife downward into the limb before drawing it back upward and then piercing the skin from the underside of the incision.

Czy mogę prosić o pomoc w przetłumaczeniu końcówki ostatniego zdania - od słowa downward. Nie bardzo umiem to sobie wyobrazić i nie wiem co w tym wypadku oznacza from the underside of the incision.