Tulip head and collet for a poly axial screw
a poly axial screw and collet technology, applied in the field of connectors, can solve the problems of requiring more tissue damage and/or incisions, unable to achieve the rigidity or stability required, and unable to assemble, bulky,
Active Publication Date: 2020-08-27
BERRY BRET MICHAEL
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- Abstract
- Description
- Claims
- Application Information
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Benefits of technology
[0014]According to an embodiment of the present invention, provided is a tulip head compromised of two sides engaged by a joint. The top of each side is attached to the other by a hinge joint. The collet may also he connected at this hinge joint. In some embodiments, a tulip fastener may engage with the tulip head. In some embodiments, the upper section of the tulip head includes a threaded portion, corresponding to a threaded portion along an interior portion of a tulip fastener, for the fastening of the tulip fastener to the tulip head. In some embodiments, the exterior portion of the upper section of each side of the tulip head includes a partial spiral wedge having a divot at one end. Each spiral wedge may be deeper at the edge of the tulip head and shallower at the middle of the tulip head. In an exemplary embodiment, the tulip fastener may be placed onto the tulip head such that the locking protrusions on the tulip fastener may easily slide into the deeper portions or divots at one end of the spiral wedges. As the tulip fastener is twisted, the locking protrusions become pressed against the shallow portions of the spiral wedges to secure the tulip fastener o the tulip head.
Problems solved by technology
In mono axial screws, the head of the screw can be aligned with the position of the rod only to a limited extent, necessitating complicated bending to correct the angle.
While poly axial screws allow more flexibility in positioning of the screw shafts and fusion rods, they often lack the rigidity or stability required to achieve and maintain an accurate angular placement during surgery, may be difficult to connect to a fusion rod, and / or create even more bulky structures that interfere with surgery, causing more tissue damage and / or require larger incisions.
Typically, the parts of a poly axial screw are configured for pre-assembly before implantation, the shape, size or number of their parts making them complicated to assemble, bulky, and / or are difficult to implant.
The resulting system may lack flexibility or rigidity or both.
The bulk of the poly axial screw system can also complicate surgery before and after implanting of the screws, as it may require larger or different incisions and more soft tissue may have to be removed, thus complicating surgery and prolonging healing times. Also the bulky structure, once implanted, may interfere with the view of the surgeon during the ongoing surgery, e.g. during placement of bone implants, and also if discs (between the vertebrae removed and replaced with interbodies, as is often the case (e.g. herniated discs).
Further the bulk may interfere with imaging techniques to determine correct placement of the screw system itself, or of the placement of related therapeutic components, such as interbody transplants and positioning tools.
The provisionally loosely tightening typically results in unpredictable inconsistent results with regards to adjustability—the fastener may have been tightened to little, resulting in the correct position being lost, e.g. as the structure shifts in the course of the ongoing surgery as the structure or the surrounding bone and tissue is manipulated, or the fastener may have been tightened too much, so adjustments cannot be made without first loosening it again, applying unnecessary torque or requiring use of an anti-torque device.
Method used
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[0038]The present invention generally relates to connectors that connect poly axial screws with fusion rods for use in spinal fusion surgery, and to poly axial screw systems comprising such connectors. In particular, the present invention relates to poly axial screw systems configured to provide an adjustably locked preliminary, and a fixated final position for the tulip with fusion rod.
[0039]The poly axial screw system of the present invention is configured for assembly during surgery, after implantation of the screw shaft (see FIG. 1). The system comprises a two-part tulip connector with a head and a collet (see FIG. 2) that is adapted to lock onto the ball head of the implanted screw shaft.
[0040]According to embodiments of the present invention, the tulip head and collet are configured with a loose and a locked position when engaging with each other and with the ball head of the screw shaft during assembly of the poly axial screw system. In the loose position, the tulip head loos...
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The present invention generally relates to connectors that connect bone screws with fusion rods for use in stabilizing surgery such as spinal fusion surgery, and to bone screw systems comprising such connectors. In particular, the present invention relates to poly axial screw systems configured to attach the poly axial tulip head after the bone screw has been implanted. Furthermore, embodiments of the present invention relate to tulip connectors which have a hinged joint and a collet that are configured to rotatably and pivotably lock onto the ball head of a poly axial screw shaft. The poly axial tulip head features a collet which can attach to the rod prior to insertion onto the bone screw. The tulip head and rod are then affixed to the bone screw with a nut.
Description
FIELD OF THE INVENTION[0001]The present invention generally relates to connectors that connect bone screws with fusion rods for use in stabilizing surgery such as spinal fusion surgery, and to bone screw systems comprising such connectors. In particular, the present invention relates to poly axial screw systems configured to provide a stable but adjustable angular placement. Furthermore, embodiments of the present invention relate to tulip connectors which have a head and a collet, that are configured to rotatably and pivotably lock onto the ball head of a poly axial screw shaft which are detachable from the screw shaft, and to methods of attaching said tulip head to the screw shaft.BACKGROUND OF THE INVENTION[0002]Poly axial screws are used e.g. for fixation of a patient's spinal column in spinal surgery that is performed to fuse individual spinal vertebrae. A screw shaft is inserted into the bone, e.g. the pedicle of each vertebrae to be fused, and a fusion rod is attached by conn...
Claims
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IPC IPC(8): A61B17/70A61B17/86
CPCA61B17/7035A61B17/7032A61B17/8605A61B2017/564A61B17/7001A61B17/7037A61B17/866A61B2090/037
InventorBERRY, BRET MICHAEL
OwnerBERRY BRET MICHAEL