Sensing of surgical instrument placement relative to anatomic structures

A measurement system for use with a powered surgical instrument for sensing a position of a leading edge of a tool relative to anatomic structures of a patient, the measurement system comprising:

• a first sensor disposed with respect to the powered surgical instrument to measure a tool drive parameter that is characteristic of the tool portion acting on the patient and output a tool drive signal representative the tool drive parameter as the tool portion is advanced relative to anatomy of the patient;
• a displacement sensor disposed with respect to the powered surgical instrument to measure an axial displacement of the leading edge of the tool portion relative to a reference point and output a displacement signal representative of the axial displacement;
• and
• a controller in operative communication with the first sensor to receive the tool drive signal and in operative communication with the displacement sensor to receive the displacement signal, wherein the controller is operative to identify a change in the tool drive parameter over a given amount of axial displacement of the leading edge of the tool portion that is indicative of the leading edge of the tool portion moving through an interface between anatomic structures of the patient. and wherein the controller is operative to determine an integrated tool drive parameter comprising a sum of the tool drive parameter over a given plurality of instances of the given amount of axial displacement of the leading edge of the tool portion.