Forceps with spring loaded end effector assembly

A vessel or tissue sealing instrument, comprising:

• a handle assembly having an elongated shaft extending therefrom, the shaft being movable relative to the handle assembly by an actuator;
• an end effector assembly attached to a distal end of the shaft, the end effector assembly having first and second jaw members being movable about a pivot from a first position in spaced relation relative to one another to a second position for clamping tissue, wherein a gap distance in the range of about 0.001 inches to about 0.006 inches is defined between the first jaw member and the second jaw member when the jaw members are in the second position;
• a knife actuator for advancing a knife through tissue held between jaw members;
• wherein each of the jaw members includes:
• an insulative outer housing having an electrically conductive, inwardly facing tissue contacting surface;
• a proximal flange having at least one camming surface disposed proximal to the pivot, the proximal flange including a spring-like tail which mounts within the distal end of the elongated shaft to bias the jaw members in an open configuration, wherein a proximal portion of the spring-like tail is biased radially outward within the distal end of the elongated shaft and wherein the proximal flange cooperates with the distal end of the elongated shaft to provide a clamping pressure within the range of about 3 kg/cm2 to about 16 kg/cm2 to effectively seal tissue upon application of electrosurgical energy;
• the actuator being movable relative to the handle to actuate the elongated shaft from a first position wherein the elongated shaft remains proximal to the proximal flanges of the jaw members and the jaw members are biased in a open configuration to at least one subsequent position wherein the distal end of the elongated shaft cams the proximal flanges to pivot the jaw members toward the second position to clamp tissue.