Method for using a trocar for penetration and skin incision

A method for establishing a surgical port for an internal body cavity during endoscopic or arthroscopic surgery on a patient, said method comprising:

• a) providing a trocar having an obturator assembly and a cannula assembly surrounding said obturator assembly, said obturator assembly capable of being inserted into and withdrawn from said cannula assembly, said obturator assembly having;
• i) an obturator, said obturator including a flat cutting blade at a distal end of said obturator, said flat cutting blade having first and second planar surfaces generally parallel to each other, said planar surfaces converging to a cutting edge surface, and a handle at a proximal end of said obturator;
• ii) a shield slidably mounted on said obturator, said shield movable from a precocked position wherein said shield is retracted so as to expose said flat cutting blade of said obturator, to an extended position wherein said shield covers said flat cutting blade, said shield having a shield retaining surface thereon and a precock surface thereon;
• iii) a precock lever movable from an unactuated position wherein said shield is in the extended position to an actuated position wherein said shield is in the precocked position, said precock lever having a shield retraction surface cooperable with said precock surface of said shield for moving said shield from the extended position to the precocked position when said precock lever is moved from the unactuated position to the actuated position;
• and
• iv) a shield retaining subassembly cooperable with said shield retaining surface of said shield, said shield retaining subassembly adapted to hold said shield in the precocked position when said precock lever has been moved from the unactuated position to the actuated position;
• b) moving the precock lever from the unactuated position to the actuated position so as to expose said flat cutting blade of said obturator upon retraction of said shield from its extended position to its precock position;
• c) incising the skin of the patient with said exposed flat cutting blade of said obturator;
• d) applying a penetrating force against the incised skin with said exposed flat cutting blade of said obturator so as to gain entry of said trocar into the internal body cavity of the patient;
• and
• e) removing said obturator assembly from said cannula assembly so as to provide the surgical port through the cannula assembly into the internal body cavity of the patient.