US Patent 11517326 Methods and systems of determining drill breakthrough during surgical drilling

A handheld surgical instrument includes a motor that transmits rotational movement to a drill bit of the handheld surgical instrument. The drill bit extends through a depth measurement module with a depth measurement extension, and a cannula, which extends forward from the drill to measure bore depth. The depth measurement extension is moveably mounted to the drill so as to extend into the rotor bore of the motor. As the drill advances forward, the depth measurement extension remains static. As a result of the advancement of the drill, the rotor extends over the proximal end of the depth measurement extension. A controller is configured to determine a breakthrough time and a breakthrough displacement of the drill bit based on displacement data and derived signals. The controller is further configured to determine a proper length of a screw to be used in a fixation surgical procedure based on the displacement data.