Bone anchoring device
A bone anchoring device for anchoring a rod to a bone or vertebra includes a receiving part with two legs defining a channel for the rod and a variable configuration member with a first rod contact surface configured to extend axially above a bottom of the channel to contact the rod. When a rod is inserted in the channel, the variable configuration member is adjustable from a first configuration where the first rod contact surface is at a first axial position relative to the receiving part and blocks the rod from contacting a second rod contact surface below the first rod contact surface, and a second configuration where the first rod contact surface is at a second axial position below the first axial position relative to the receiving part to permit the rod to contact the second rod contact surface.
1 . A bone anchoring device for anchoring a rod to a bone or vertebra, the bone anchoring device comprising:
a bone anchoring element comprising a shank and a head;
a receiving part having a first end, a second end below the first end, a central axis extending between the first and second ends, a channel at the first end for receiving the rod, and an accommodation space at the second end for accommodating the head of the bone anchoring element;
a pressure member movable in the receiving part to directly engage and exert pressure on the head, wherein a portion of the pressure member is configured to extend to an axial position that is lower than an axial position of a greatest diameter of the head measured in a direction perpendicular to the central axis; and
a separate ring-shaped member configured to be assembled to and movable relative to the receiving part;
wherein when the head, the pressure member, and the ring-shaped member are assembled to the receiving part and when the ring-shaped member is at a first configuration, the ring-shaped member is configured to block the pressure member from being moved axially downwardly towards the second end of the receiving part; and
wherein the ring-shaped member is adjustable from the first configuration to a second configuration where at least part of the pressure member is movable axially downwardly past at least part of the ring-shaped member to increase the pressure exerted on the head.
2 . The bone anchoring device of claim 1 , wherein at least part of the ring-shaped member is deformable for adjusting the ring-shaped member from the first configuration to the second configuration.
3 . The bone anchoring device of claim 2 , wherein the at least part of the ring-shaped member is elastically deformable.
4 . The bone anchoring device of claim 1 , wherein the ring-shaped member is positionable around the receiving part.
5 . The bone anchoring device of claim 1 , wherein the ring-shaped member comprises a rod contacting surface configured to extend into the channel to engage the rod and to block the rod from engaging the pressure member when the ring-shaped member is at the first configuration.
6 . The bone anchoring device of claim 1 , wherein part of the pressure member is configured to extend into the channel to engage the rod.
7 . The bone anchoring device of claim 1 , wherein when the ring-shaped member is at the first configuration, the head is pivotable relative to the receiving part.
8 . The bone anchoring device of claim 1 , wherein the ring-shaped member is configured to be spaced apart from the head.
9 . The bone anchoring device of claim 1 , wherein the pressure member and the ring-shaped member are devoid of any axial abutments relative to one another at least when the ring-shaped member is at the second configuration.
10 . A bone anchoring device for anchoring a rod to a bone or vertebra, the bone anchoring device comprising:
a bone anchoring element comprising a shank and a head;
a receiving part having a first end, a second end below the first end, a central axis extending between the first and second ends, a channel at the first end for receiving the rod, and an accommodation space at the second end for accommodating the head of the bone anchoring element;
a pressure member movable in the receiving part to directly engage and exert pressure on the head; and
a separate deformable member configured to be assembled to and movable relative to the receiving part;
wherein when the head, the pressure member, and the deformable member are assembled to the receiving part and when the deformable member is at a first configuration, the deformable member is configured to block the pressure member from being moved axially downwardly towards the second end of the receiving part; and
wherein the deformable member is deformable from the first configuration to a second configuration where the pressure member is movable axially downwardly to increase the pressure exerted on the head, while the deformable member is configured to be spaced apart from the head, and while the pressure member and the deformable member are devoid of any axial abutments relative to one another.
11 . The bone anchoring device of claim 10 , wherein the deformable member is elastically deformable.
12 . The bone anchoring device of claim 10 , wherein the deformable member is positionable around the receiving part.
13 . The bone anchoring device of claim 10 , wherein the deformable member comprises a rod contacting surface configured to extend into the channel to engage the rod and to block the rod from engaging the pressure member when the deformable member is at the first configuration.
14 . The bone anchoring device of claim 10 , wherein part of the pressure member is configured to extend into the channel to engage the rod.
15 . The bone anchoring device of claim 10 , wherein when the deformable member is at the first configuration, the head is pivotable relative to the receiving part.
16 . The bone anchoring device of claim 10 , wherein when the deformable member is at the second configuration, the pressure member is movable further axially downwardly to further increase the pressure exerted on the head.
17 . The bone anchoring device of claim 10 , wherein when the deformable member is at the second configuration, at least part of the pressure member is movable to a same axial position as at least part of the deformable member.