Circular frame reaction force sensing

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
• at least one detector disposed within or adjacent to the adjustment knob, wherein the at least one detector is configured to detect an amount of tissue compression of tissue clamped between the anvil and the stapling head prior to firing of the circular stapler.