Stapler with composite cardan and screw drive

A surgical instrument comprising:

• a base;
• a first jaw having a first jaw axis and that includes a proximal portion pivotally mounted to the base to be pivotable about a pivot axis between an open and a closed positions and including a distal portion;
• a second jaw having a second jaw axis and including a proximal portion secured to the base and including a distal portion;
• a first cam surface secured to the first jaw that includes a distal cam portion that extends parallel to the first jaw axis and a proximal rotation cam portion that is inclined at an angle relative to the distal cam portion;
• a second cam surface secured to the second jaw that extends parallel to the second jaw axis;
• a drive member including a cross-beam, which is sized to slideably engage the first and second cam surfaces, a first transverse beam portion, and a second transverse beam portion;
• and
• a lead screw configured to advance the drive member in a distal direction parallel to the second jaw axis;
• wherein while the first jaw is in the open position, the proximal rotation cam portion and the second cam surface are disposed to contact the first and second transverse beam portions, respectively, and the proximal rotation cam portion is disposed to impart a rotational force to the first jaw about the pivot axis as the lead screw advances the drive member in the distal direction;
• and
• wherein while the first jaw is in the closed position, the distal cam portion and the second cam surface are disposed, to contact the first and second transverse beam portions, respectively, and to impart a clamp force to the first and second jaws as the lead screw advances the drive member in the distal direction;
• a metal drive shaft, including a proximal portion and a distal portion and including a first clevis at the distal portion of the drive shaft, the first clevis including first opposed facing arms therein, the drive shaft defining first opposed facing holes therein, the drive shaft configured to impart a rotational drive force;
• a metal driven shaft, including a proximal portion and a distal portion and including a second clevis at the proximal portion of the driven shaft, the second clevis including second opposed facing arms defining second opposed facing holes therein, the driven shaft configured to impart the rotational drive force to the lead screw;
• a universal double joint including:
• a metal sleeve member defining a proximal end opening and a distal end opening;
• a first metal cross pin defining a first cross pin bore;
• a second metal cross pin defining a second cross pin bore;
• a first rotatable bearing including a first spherical surface formed of a plastic material, sized to fit within the proximal end opening of the sleeve member for smooth rotation therein, including a first axial engagement structure, and defining a distal opening and a first transverse bore, the first clevis extending within the distal opening such that the first opposed facing holes align with the first transverse bore;
• the first cross pin extending within the aligned first opposed facing holes and the first transverse bore, such that the first cross pin couples the first rotatable plastic bearing to rotate in unison with the metal drive shaft;
• a second rotatable bearing having a second spherical surface formed of a plastic material, sized to fit within the distal end opening of the sleeve member for smooth rotation therein, including a second engagement structure, and defining a proximal opening and a second transverse bore, the second clevis extending within the proximal opening such that the second opposed facing holes align with the second transverse bore;
• the second cross pin extending within the aligned second opposed facing holes and the second transverse bore, such that the second cross pin couples the second rotatable plastic bearing to rotate in unison with the metal driven shaft;
• a first metal coupling pin extending through the first cross pin bore and rotatable within the first cross pin bore, configured to impart the drive force from the first cross pin mounted in the first clevis to the sleeve member;
• and
• a second metal coupling pin extending through the second cross pin bore and rotatable within the second cross pin bore, configured to impart drive force from the sleeve member to the second cross pin mounted in the second clevis;
• the first and second axial engagement structures configured to engage each other.