Patent ID: 8066745

Claim:
A spinal fixation assembly comprising: a receiver having a bore for receiving a screw having a threaded portion and a screw head that is received in said bore, wherein said bore has an opening at a first end of said receiver through which said threaded portion and said screw head pass when said screw is received in said receiver and a second opening at a second end of said receiver through which only said threaded portion passes until said screw head is received in a seat of said receiver; a compression member dimensioned to be received in said bore and having a first end for receiving an elongated member and a second end for engaging said screw head; said receiver comprising a receiving channel for receiving an elongated member: said receiver further comprising a first wall, a second wall generally opposing said first wall, and a third wall coupling said first and second walls to define a first locking channel and further comprising a fourth wall, a fifth wall generally opposing said fourth wall, and a sixth wall coupling said fourth and fifth walls to define a second locking channel; said first and second locking channels being non linear and spiraling or revolving in a general helix about an axis of said receiver; said compression member comprising a compression member wall that is generally U-shaped and adapted to define a compression member seat; at least one of said first, second or third walls of said first locking channel cooperating with at least one of said fourth, fifth or sixth walls to define at least one camming surface that engages said elongated member and urges it downward in response to rotary movement of said receiver, which causes generally axial movement of said compression member such that said compression member engages and applies a compressive force against said screw head until said screw head becomes locked to said receiver, and substantially simultaneously, said elongated member becomes captured or locked in said first and second locking channels.