Patent ID: 11911076
Assignee: SOUTHERN CROSS PATENTS PTY LTD
Field: Medical technology (Instruments)
Classification: CPC A | IPC A

Claim 0:
1. A modular pedicle screw assembly comprising:
a bone screw having a threaded bone shaft adapted for insertion in a vertebra;
a polyaxial inner collet configured in an operative position to clamp about a head of the bone screw, said head being substantially ball-shaped with a truncated surface wherein the polyaxial inner collet includes a cavity defining an internal surface configured to permit polyaxial movement of the polyaxial inner collet in an inoperative position about the head of said bone screw;
a seat arranged to provide seating for retention of the polyaxial inner collet, the seat designed to move polyaxially in conjunction with the polyaxial inner collet in the inoperative position about the head of said bone screw;
an insert frangibly connected to the polyaxial inner collet to release from said polyaxial inner collet and locate at the truncated surface of the head of the bone screw, the polyaxial inner collet in i) the inoperative position thus being mobilized for polyaxial movement about the head of the bone screw, and ii) in the operative position arranged for clamping about the head of the bone screw having its effective clamping surface increased by the insert located at the truncated surface of said screw head; and
an inner collet actuator configured to engage the seat and operable to activate the polyaxial inner collet for movement into the operative position for clamping about the head of the bone screw to lock the polyaxial inner collet and the seat to the head of said bone screw.