Anvil connection detection of circular stapler

A circular stapler comprising:

• a housing with a handle extending from the housing;
• a shaft coupled to and extending from the housing in a different direction than the handle;
• a stapling head coupled to a distal end of the shaft, the stapling head being configured to cut tissue and dispense one or more staples into tissue;
• an adjustment knob rotatably coupled to the housing, the adjustment knob being coupled to a first end of a pushrod extending through the housing and the shaft;
• a trocar coupled to a second end of the pushrod, the trocar being positioned within and axially translatable relative to the stapling head;
• an anvil removably coupled to a distal end of the trocar;
• and
• a feedback system disposed within the housing or the stapling head, wherein the feedback system comprises at least one sensor configured to detect connection of the anvil to the trocar.

A circular stapler comprising:

• a housing with a handle extending from the housing;
• a shaft coupled to and extending from the housing in a different direction than the handle;
• a stapling head coupled to a distal end of the shaft, the stapling head being configured to cut tissue and dispense one or more staples into tissue;
• an adjustment knob rotatably coupled to the housing, the adjustment knob being coupled to a first end of a pushrod extending through the housing and the shaft;
• a trocar coupled to a second end of the pushrod, the trocar being positioned within and axially translatable relative to the stapling head;
• an anvil removably coupled to a distal end of the trocar;
• and
• a feedback system disposed within the housing or the stapling head, wherein the feedback system is configured to detect connection of the anvil to the trocar before retraction of the trocar into the stapling head, wherein detection of the connection of the anvil to the trocar comprises comparing a torque response of the trocar against a threshold torque value, which torque response is based on a predetermined sequence of motions of the trocar.