The chainsaw was originally invented to assist with childbirth. Specifically, two Scottish doctors created a small, hand-operated chain saw in the 1780s to cut through pelvic bone and cartilage when a baby became stuck in the birth canal. It looked nothing like the gas-powered machines used to fell trees today. The original was a fine serrated chain with handles on either end, small enough to be used in surgery.
The Medical Problem It Solved
In the 18th century, a difficult childbirth could easily become fatal. When a baby was too large to pass through the mother’s pelvis, or the pelvis was too narrow due to conditions like rickets, doctors had limited options. Cesarean sections existed but were extremely dangerous and almost always killed the mother. The alternative was a procedure called symphysiotomy: manually widening the pelvis by cutting through the cartilage and bone at the front of the pubic joint.
Before the chain saw existed, surgeons performed this procedure with a knife or a regular bone saw. Both were slow, imprecise, and agonizing, especially in an era when anesthesia was rarely available. The process of sawing through bone with conventional tools was brutal for the patient and difficult for the surgeon, particularly in the tight, hard-to-reach space of the pelvis.
Who Invented It and When
Scottish doctors John Aitken and James Jeffray independently developed the concept between roughly 1783 and 1790. Aitken’s version is described in a 1785 medical text called Principles of Midwifery as a “flexible saw contrived to be used when there is obstructive bone.” It worked like a watch chain with small cutting teeth, designed to saw from the inside outward. The surgeon would thread the chain around the bone and pull it back and forth using the two handles.
Jeffray claimed he had conceived the idea independently around the same time but wasn’t able to have a working version produced until 1790. Both doctors also saw the tool’s potential for removing diseased bone outside of childbirth, making it useful in broader surgical contexts.
How It Differed From Modern Chainsaws
The original medical chain saw shared a basic concept with today’s chainsaws (a cutting chain moving along a guide), but that’s where the similarities end. It was a hand-powered tool small enough to fit into a surgical field. The chain was fine and serrated, nothing like the heavy-duty cutting chains on a modern logging saw. It had no motor, no guide bar, and no housing. Think of it as closer to a piece of surgical wire with teeth than to anything you’d find in a hardware store.
The tool had real limitations. The chain sometimes broke during use or got trapped in the patient’s bone. And its hand-powered speed wasn’t fast enough to cut through dense, compact bone efficiently. It was an improvement over a knife, but still far from ideal.
The Osteotome: A Critical Upgrade
In 1830, German physician Bernhard Heine refined the concept into a device he called the osteotome. This was the first mechanical chain saw. Instead of pulling a chain back and forth by hand, Heine added a hand crank that drove an endless loop of chain around a guide. The mechanism cut through bone quickly without subjecting the patient to the jarring blows of a hammer and chisel or the rough vibration of a standard amputation saw. In a time when patients were typically awake during surgery, that difference mattered enormously.
Heine’s osteotome is considered the direct ancestor of the modern chainsaw. It established the core mechanical principle: a toothed chain rotating continuously around a bar, powered by a crank or motor.
From Operating Rooms to Forests
The leap from bone surgery to timber took over a century. In 1905, a San Francisco inventor named Samuel J. Bens recognized that the chain-cutting mechanism could work on wood, specifically the massive redwood trees of California. He filed a patent for what became the first recognizably modern chainsaw designed for logging.
Even then, practical gasoline-powered chainsaws didn’t arrive until the late 1920s. The German company Stihl produced its first gas chainsaw in 1929. It weighed 46 kilograms (about 101 pounds) and required two people to operate. With 6 horsepower, it was a far cry from the lightweight one-person saws available today, but it revolutionized forestry work. From that point forward, the chainsaw’s identity shifted entirely. Its medical origins faded into obscurity, only to resurface periodically as one of history’s more unsettling pieces of trivia.
Why Symphysiotomy Fell Out of Favor
The procedure the chainsaw was invented for didn’t last. Symphysiotomy carried serious complications: hemorrhage, damage to the urinary tract, and long-term difficulty walking. As surgical techniques and hygiene improved through the 19th and 20th centuries, cesarean sections became dramatically safer. C-sections eventually replaced symphysiotomy almost entirely in modern obstetrics. The tool that was built to make a dangerous birth procedure faster and less painful ended up outliving the procedure itself, just in an entirely different industry.