How is an obsidian scalpel similar to the stone tools used by early humans?

An obsidian scalpel is constructed exactly the same way the early humans made stone knives. A skill stoneworker uses a pressure flaking technique to force a small flake of obsidian from a larger stone. The flake is examined to see if it is a suitable shape for a blade - if not the flake is discarded and the stoneworker gets another flake from the stone. Although very sharp the obsidian blade is very thin and cannot withstand lateral force on the blade. Surgeons must be very careful to cut only soft tissues with the obsidian scalpel. Attempting to cut or scrape bone could result in breakage, which could leave obsidian flakes inside the patient.