POLYAXIAL BONE SCREW
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Abstract
The present invention generally provides a polyaxial fixation device having a shank with a spherical head formed on a proximal end thereof, and a receiver member having an axial passage formed therein that is adapted to polyaxially seat the spherical head of the shank. The polyaxial bone screw further includes an engagement member that is adapted to provide sufficient friction between the spherical head and the receiver member to enable the shank to be maintained in a desired angular orientation before locking the spherical head within the receiver member.
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Citations
36 Claims
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1-20. -20. (canceled)
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21. A polyaxial fixation device, comprising:
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a receiver member having an axial passage extending through a distal surface thereof; a bone screw having a shank extending distally from the axial passage and a spherical head formed on the shank and seated in directed contact with the distal surface of the receiver member; a compression cap disposed within the receiver member and having a proximal surface configured to seat a spinal fixation element and a distal surface configured to engage the spherical head of the bone screw; and an engagement member disposed within the receiver member and spaced a distance apart from and distal of the compression cap, the engagement member being configured to provide sufficient friction between the spherical head and the receiver member to enable the shank to be maintained in a desired angular orientation before locking the spherical head within the receiver member. - View Dependent Claims (22, 23, 24, 25, 26, 27)
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28. The polyaxial fixation device of claim
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29. A polyaxial fixation device, comprising:
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a receiver head having opposed arms configured to receive a spinal fixation element therebetween, and an axial passage extending through a distal surface thereof; a bone screw having a shank extending distally from the axial passage and a spherical head formed on the shank and seated in directed contact with the distal surface of the receiver member; and a collet having a plurality of spaced, expandable members disposed therearound and adapted to engage the spherical head of the shank. - View Dependent Claims (30, 31)
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32. A polyaxial fixation device, comprising:
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a receiver head having opposed arms configured to receive a spinal fixation element therebetween, and an axial passage extending through a distal surface thereof; a bone screw having a shank extending distally from the axial passage and a spherical head formed on the shank and seated in directed contact with the distal surface of the receiver member; and a compression cap disposed within the receiver member and having a concave distal surface adapted to seat at least a portion of the spherical head of the shank, the compression cap being matable with the receiver member such that the compression cap is effective to retain the spherical head of the bone screw in the receiver member, and the compression cap having opposed leaf-spring members and the receiver member having opposed deformable portions that, upon deformation, are effective to contract the leaf-spring members to cause the compression cap to frictionally engage the spherical head of the shank. - View Dependent Claims (33, 34, 35, 36)
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Specification