Drill for surgical screw insertion with reoriented torque

An instrument for rotatably driving a screw or drill bit into bone in surgery, comprising

• a. a drive shaft having a rotational power source at a proximal end for applying a rotational force to the shaft and a gear housing at a distal end of the drive shaft;
• b. wherein the distal end of the drive shaft is connected to a first bevel gear supported in the gear housing, such that the larger diameter of the first bevel gear is in the proximal orientation, such that rotation of the drive shaft causes the first bevel gear to rotate;
• c. wherein the first bevel gear meshes with a second bevel gear having an axis of rotation at a 25°-55° angle to direct a torque from the second bevel gear at the 25°-55° angle along a first internal shaft, wherein the internal shaft terminates at a first spur gear;
• d. wherein the first spur gear meshes with a second spur gear, wherein the second spur gear drives a second internal shaft that is coupled to a head that rotatably drives a surgical screw or drill at a 115°-145° angle from the drive shaft.

An instrument for rotatably driving a screw or drill bit into bone in surgery, comprising:

• a. a drive shaft having a rotational power source at a proximal end for applying a rotational force to the shaft and a gear housing at a distal end of the drive shaft;
• b. wherein the distal end of the drive shaft is connected to a first bevel gear supported in the gear housing, such that the larger diameter of the first bevel gear is in the proximal orientation, such that rotation of the drive shaft causes the first bevel gear to rotate;
• c. wherein the first bevel gear meshes with a second bevel gear having an axis of rotation at a 25°-55° angle with respect to the drive shaft to direct a torque from the second bevel gear at the 25°-55° angle along a first internal shaft, wherein the internal shaft terminates at a first spur gear;
• d. wherein the first spur gear meshes with at least one additional second spur gear, wherein rotation of the at least one additional second spur gear causes a lead screw to rotate;
• e. wherein the lead screw meshes with a drive stage housing containing a first drive gear, such that rotation of the lead screw causes the first drive gear to rotate, and wherein rotation of the first drive gear causes the drive stage housing to move longitudinally along the lead screw;
• f. wherein a second drive gear in the drive stage housing meshes with the first drive gear, such that rotation of the first drive gear causes the second drive gear to rotate, and wherein the second drive gear is connected to a head that rotatably drives a surgical screw or drill bit at a 115°-145° angle from the drive shaft, and wherein the longitudinal motion of the drive stage housing moves in synchronization with the lead screw to maintain a firm contact of the head with the screw or drill bit as the screw or drill bit is rotatably driven into bone during a surgical procedure.