Bone fixing device, in particular for fixing to the sacrum during osteosynthesis of the backbone

A bone fixing device for use in osteosynthesis of the backbone, the device comprising:

• an integral link member having a longitudinal direction, a top region having a plurality of first threads, a bottom region, a plurality of spherical bearing surfaces in the bottom region, each spherical bearing surface being adjacent to at least one other spherical bearing surface in the longitudinal direction and associated with one first thread in the top region, the integral link member further having an elongated through orifice coupling each spherical bearing surface;
• at least one bone fastening screw adapted to be received in the elongated orifice whereby the bone fastening screw may be moved from one bearing surface to another bearing surface without extracting the screw from the orifice, each screw having a head with an essentially spherical surface adapted to bear against a spherical bearing surface of the integral link member;
• and
• at least one plug having a second thread adapted to cooperate with one of the first threads and further adapted to come into clamping contact with the head of at least one bone fastening screw to hold the screw against one of the bearing surfaces in a desired angular position.

A bone fixing device for use in osteosynthesis of the backbone, the device comprising:

• a link member having a through orifice, the through orifice having a top region having a first thread and a bottom region having a spherical bearing surface;
• a bone fastening screw adapted to be received in the orifice, the bone fastening screw having a head with an essentially spherical surface adapted to bear against the spherical bearing surface;
• a plug having a second thread adapted to cooperate with the first thread and further adapted to come into clamping contact with the head of the bone fastening screw through torque applied to the plug to hold the screw against the bearing surface in a desired angular position, thus creating a stiffness of assembly;
• and
• a stiffness-attenuating material coupled to at least part of the screw head whereby stiffness of assembly between the link member and the bone fastening screw is reduced.

A bone fixing device for use in osteosynthesis of the backbone, the device comprising:

• a link member having a through orifice, the through orifice having a top region having a first thread and a bottom region;
• a flexible O-ring in the shape of spherical bearing surface and located in the bottom region of the orifice;
• a bone fastening screw adapted to be received in the orifice, the bone fastening screw having a head with an essentially spherical surface adapted to bear against the spherical bearing surface;
• and
• a plug having a second thread adapted to cooperate with the first thread and further adapted to come into clamping contact with the head of the bone fastening screw through torque applied to the plug to hold the screw against the bearing surface in a desired angular position, thus creating a stiffness of assembly.

A bone fixing device for use in osteosynthesis of the backbone, the device comprising:

• a link member having a through orifice, the through orifice having a top region having a first thread and a bottom region;
• a cylindrical rod having a cylindrical circumference;
• a rigid ring in the shape of spherical bearing surface and located in the bottom region of the orifice;
• a bone fastening screw adapted to be received in the orifice, the bone fastening screw having a head with an essentially spherical surface adapted to bear against the spherical bearing surface;
• a top-loading screw fixed about the cylindrical circumference of the cylindrical rod;
• and
• a plug having a second thread adapted to cooperate with the first thread and further adapted to come into clamping contact with the head of the bone fastening screw through torque applied to the plug to hold the screw against the bearing surface in a desired angular position, thus creating a stiffness of assembly.