Low Friction Rod Persuader
First Claim
1. An instrument for reducing a spinal rod, the instrument comprising:
- an elongate clamp member configured for receiving a coupling member of a spinal fixation system;
a drive member rotatably coupled to the clamp member, the drive member including a helical groove;
at least one rolling 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 rolling element such that rotation of the drive member causes the reducer member to be linearly advanced with the rolling 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 an advanced position thereof.
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Accused Products
Abstract
Instruments are provided for shifting elongate members, such as spinal rods, with respect to coupling members of spinal fixation systems. The instruments include a low friction drive mechanism having one or more rolling elements that ride along a helical groove or track in order to transform rotational movement of a drive member into linear shifting of a reducer member that shifts the elongate member. A one-way locking mechanism may be provided to selectively prevent unwanted counter-rotation of the low friction drive mechanism. The one-way locking mechanism may include annular ratchet teeth arranged on the exterior of the drive member and a ratchet pawl located adjacent to the teeth and selectively engageable therewith.
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Citations
10 Claims
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1. An instrument for reducing a spinal rod, the instrument comprising:
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an elongate clamp member configured for receiving a coupling member of a spinal fixation system; a drive member rotatably coupled to the clamp member, the drive member including a helical groove; at least one rolling 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 rolling element such that rotation of the drive member causes the reducer member to be linearly advanced with the rolling 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 an advanced position thereof. - View Dependent Claims (2, 3, 4, 5)
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6. An instrument for reducing a spinal rod comprising:
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An elongate clamp member for receiving a coupling member of a spinal fixation system, the clamp member comprising a hollow, generally cylindrical first end and a second end comprising a plurality of clamping arms, the generally cylindrical first end having at least one elongate slit disposed therein; a drive member rotatably disposed in the generally cylindrical first end of the clamp member, the drive member including a helical groove about its exterior; at least one rolling element partially disposed in the helical groove of the drive member and partially disposed within the elongate slit of the clamp member; an elongate reducer sleeve disposed about the clamp member and 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 rolling element; and a one-way locking mechanism comprising; an annular array of ratchet teeth coupled to the exterior of the drive member; a ratchet pawl disposed adjacent to the ratchet teeth; and a ratchet control member that holds the ratchet pawl against the ratchet teeth when shifted to a first position and allows the ratchet pawl to shift away from the ratchet teeth when the control member is shifted to a second position; wherein rotation of the drive member causes linear shifting of the reducer sleeve due to the interaction between the helical groove, the rolling element, and the reducer sleeve; and
wherein the one-way locking mechanism allows rotation of the drive member in two directions when the control member is in the first position but allows rotation of the drive member in only one direction when the control member is in the second position. - View Dependent Claims (7, 8, 9, 10)
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Specification