Bone anchoring device
First Claim
1. A polyaxial bone anchoring device comprising:
- a bone anchoring element having a head and a shaft for anchoring to a bone;
a receiving part for coupling the bone anchoring element to a rod, the receiving part having a head receiving portion with an accommodation space for accommodating the head, and a rod receiving portion having an inner wall defining a bore in communication with the accommodation space, the bore having a bore axis; and
a pressure member movable in the bore and comprising a first surface for engaging the head and a second surface for engaging a rod;
wherein when the bone anchoring element and the pressure member are in the receiving part, the pressure member is movable to a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and to a second position different from the first position where the head is locked relative to the receiving part; and
wherein the pressure member is configured to engage a first portion of the inner wall of the receiving part that faces the bore axis without a positive lock, wherein a holding force is generated at the engagement between the pressure member and the first portion of the inner wall of the receiving part for holding the pressure member at the first position, and wherein the pressure member is movable out of the first position by applying an axial force on the pressure member that is greater than the holding force.
2 Assignments
0 Petitions
Accused Products
Abstract
A polyaxial bone anchoring device includes a bone anchoring element having a head and a shaft, a receiving part having a head receiving portion, a rod receiving portion, and a bore having a bore axis, and a pressure member movable in the bore and having a first surface for engaging the head, wherein the pressure member is movable to a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and wherein the pressure member is configured to engage the receiving part to generate a holding force for holding the pressure member at the first position without a positive lock, and wherein the pressure member is movable in and out of the first position by applying an axial force on the pressure member greater than the holding force.
27 Citations
20 Claims
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1. A polyaxial bone anchoring device comprising:
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a bone anchoring element having a head and a shaft for anchoring to a bone; a receiving part for coupling the bone anchoring element to a rod, the receiving part having a head receiving portion with an accommodation space for accommodating the head, and a rod receiving portion having an inner wall defining a bore in communication with the accommodation space, the bore having a bore axis; and a pressure member movable in the bore and comprising a first surface for engaging the head and a second surface for engaging a rod; wherein when the bone anchoring element and the pressure member are in the receiving part, the pressure member is movable to a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and to a second position different from the first position where the head is locked relative to the receiving part; and wherein the pressure member is configured to engage a first portion of the inner wall of the receiving part that faces the bore axis without a positive lock, wherein a holding force is generated at the engagement between the pressure member and the first portion of the inner wall of the receiving part for holding the pressure member at the first position, and wherein the pressure member is movable out of the first position by applying an axial force on the pressure member that is greater than the holding force. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A method of manufacturing a polyaxial bone anchoring device comprising a bone anchoring element having a head and a shaft for anchoring to a bone, a receiving part for coupling the bone anchoring element to a rod, the receiving part having a head receiving portion with an accommodation space for accommodating the head, and a rod receiving portion having an inner wall defining a bore in communication with the accommodation space, the bore having a bore axis, and a pressure member comprising a first surface for engaging the head and a second surface for engaging a rod, wherein when the bone anchoring element and the pressure member are in the receiving part, the pressure member is movable to a first position where friction between the first surface and the head generates a preload on the head to maintain the shaft at a temporary angular position relative to the receiving part, and to a second position different from the first position where the head is locked relative to the receiving part, the method comprising:
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inserting the head of the bone anchoring element in the receiving part; inserting the pressure member in the receiving part; applying an axial force on the pressure member to move the pressure member to the first position to generate the preload on the head of the bone anchoring element, wherein the pressure member engages a first portion of the inner wall of the receiving part that faces the bore axis without a positive lock, wherein a holding force is generated at the engagement between the pressure member and the first portion of the inner wall of the receiving part for holding the pressure member at the first position, and wherein the pressure member is movable out of the first position by applying an axial force on the pressure member that is greater than the holding force. - View Dependent Claims (13, 14, 15, 16)
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17. A method for coupling a rod to a bone via a polyaxial bone anchoring device comprising a bone anchoring element having a head and a shaft for anchoring to a bone, a receiving part for coupling the bone anchoring element to a rod, the receiving part having a head receiving portion with an accommodation space for accommodating the head, and a rod receiving portion having an inner wall defining a bore in communication with the accommodation space, the bore having a bore axis, and a pressure member movable in the bore and comprising a first surface for engaging the head and a second surface for engaging a rod, and a fixation element, the method comprising:
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inserting the bone anchoring element into a bone when the head and the pressure member are in the receiving part and the pressure member is at a first position where friction between the first surface and the head generates a preload onto the head to maintain the shaft at a temporary angular position relative to the receiving part; applying a force greater than the friction on the bone anchoring element or the receiving part to adjust the angular position of the shaft relative to the receiving part, while the pressure member engages a first portion of the inner wall of the receiving part that faces the bore axis without a positive lock, wherein a holding force is generated at the engagement between the pressure member and the first portion of the inner wall of the receiving part for holding the pressure member at the first position; inserting a rod into the rod receiving portion of the receiving part; advancing the fixation element in the receiving part to advance the rod towards the head receiving portion, and to exert an axial force on the pressure member greater than the holding force to advance the pressure member out of the first position to a second position, to lock the head relative to the receiving part and to lock a position of the rod relative to the receiving part. - View Dependent Claims (18, 19, 20)
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Specification