Abstract: A method for establishing a surgical port for endoscopic or arthroscopic surgery is disclosed. A trocar is initially provided, and the obturator of the trocar includes a flat cutting blade, a shield that moves proximally and distally from a precock position to an extended position, a precock lever to move the shield proximally to expose the flat cutting blade, and a shield retaining assembly to constrain the shield in the proximal position. "Precocking" the trocar of the present invention moves the shield from the distal position wherein the flat blade is covered, to a proximal position wherein the flat blade is exposed, and the shield is constrained by the shield retaining assembly. Once the flat cutting blade is exposed, the skin of the patient is incised with the flat cutting blade of the obturator. The flat blade of the trocar is inserted into the incision and a penetrating force is applied so that the flat blade penetrates into the internal body cavity of the patient.