Normally, the finger pulleys (A2, A3, A4) hold the flexor tendons tight against the finger bones. When enough pulleys tear — usually two or more — the tendon loses that support and lifts away from the bone in a visible curve when the finger bends. The shape looks like an archer’s bow, which is where the name comes from.
Bowstringing is a sign doctors look for on exam and on ultrasound. It’s most often tied to the highest injury grade, Schöffl Grade IV, where several pulleys have torn at once.[1] It’s also a dynamic sign — the gap between tendon and bone is often only visible on ultrasound while the finger is actively gripping, not at rest.[2]
Bowstringing describes what the tendon is doing mechanically. It does not, by itself, decide whether someone needs surgery — that decision also depends on how many pulleys are torn, ongoing grip demands, and time since the injury.