chain saw to assist in a procedure known as a symphysiotomy.

 In the late 18th century (around 1780–1785), two Scottish doctors, John Aitken and James Jeffray, developed a hand-cranked, fine-toothed chain saw to assist in a procedure known as a symphysiotomy.  

​Here is the context behind that grim historical fact:

​The Procedure: A symphysiotomy involved cutting through the cartilage and bone of the pubic symphysis (the front of the pelvis) to widen the birth canal during obstructed labor. At the time, this was a life-saving alternative to much deadlier options, such as a C-section, which was almost always fatal in the pre-anesthesia and pre-antiseptic era.  

​The Design: Unlike the massive, gas-powered tools used in forestry today, the original medical chainsaw was a small, hand-cranked device. It featured a fine, serrated link chain that allowed surgeons to make precise, relatively quick cuts to bone and cartilage, which was far less traumatic to the surrounding tissue than the chisels and rigid saws used previously.  

​Evolution: Over the 19th century, these medical bone saws (including the Gigli twisted wire saw) were refined for various surgical amputations and bone excisions. It wasn't until the early 20th century that the mechanism was mechanized and adapted for the timber industry, eventually evolving into the powerful, engine-driven tools used today.