Patent ID: 8545505

Claim:
An instrument for reducing a spinal rod, the instrument comprising: an elongate clamp member having an axial throughbore and configured for holding a coupling member of a spinal fixation system; a rotatable drive member distinct from the clamp member, and sized to be received in the clamp member axial throughbore to be rotatably coupled to the clamp member, the drive member including a helical groove; at least one rolling ball element partially disposed in the helical groove of the drive member; an elongate reducer member configured to be linearly shifted with respect to the clamp member, the reducer member including at least one opening sized and configured to receive the at least one rolling ball element such that rotation of the drive member causes the reducer member to be linearly advanced by converting an input rotary drive force applied to the rotatable drive member to translatory motion of the elongate reducing member along the elongate clamp member with the rolling ball element transmitting drive forces therebetween to provide a low friction drive interface between the drive member and the reducer member; and a one-way locking mechanism that is operable to maintain the reducer member in a distally advanced position thereof by restricting proximal linear shifting thereof.