Abstract: A surgical screw assembly including: a fastener including an elongate shaft having a proximal end and a distal end and a head at the proximal end. A tulip having a an internal bearing surface is provided. A distal end of the tulip has a bore therethrough defining the internal bearing surface. Locking enhancement features are configured to cooperate with the head, such that, in an unlocked configuration, the head is movable relative to the tulip; in a provisionally locked configuration, the locking enhancement features engage the head with a first polyaxial grip strength; and in a finally locked configuration, the locking enhancement features engage the head with a second polyaxial grip strength greater than the first polyaxial grip strength.

Abstract: Uniplanar surgical screw assemblies described include: a fastener including an elongate shaft; a saddle-shaped tulip having a tulip having a bore therethrough dimensioned to allow the distal end of the elongate shaft to pass therethrough, but to prevent passage of the head therethrough; and one or more features for limiting angular movement of the shaft, relative to the tulip, to one plane.

Abstract: A surgical screw assembly including: a fastener including an elongate shaft having a proximal end and a distal end and a head at the proximal end. A tulip having a an internal bearing surface is provided. A distal end of the tulip has a bore therethrough defining the internal bearing surface. Locking enhancement features are configured to cooperate with the head, such that, in an unlocked configuration, the head is movable relative to the tulip; in a provisionally locked configuration, the locking enhancement features engage the head with a first polyaxial grip strength; and in a finally locked configuration, the locking enhancement features engage the head with a second polyaxial grip strength greater than the first polyaxial grip strength.

Abstract: A surgical screw assembly including: a fastener including an elongate shaft having a proximal end and a distal end and a head at the proximal end. A tulip having a an internal bearing surface is provided. A distal end of the tulip has a bore therethrough defining the internal bearing surface. Locking enhancement features are configured to cooperate with the head, such that, in an unlocked configuration, the head is movable relative to the tulip; in a provisionally locked configuration, the locking enhancement features engage the head with a first polyaxial grip strength; and in a finally locked configuration, the locking enhancement features engage the head with a second polyaxial grip strength greater than the first polyaxial grip strength.

Abstract: A surgical screw assembly is provided that includes a fastener including an elongate shaft having a proximal end and a distal end and a head at the proximal end. A tulip having an internal bearing surface and a distal end having a bore therethrough is provided to allow the distal end of the elongate shaft to pass therethrough. A first step feature located at a distal end portion of the bore and extending inwardly therefrom reduces the diameter of the bore to allow the distal end of the elongate shaft to pass therethrough, but prevents passage of the head therethrough. A second step feature located at a distal end portion of the bore, distally of the first step feature, further reduces the diameter of the bore to a dimension less than a dimension established by the first step feature, the further reduced dimension allowing the distal end of the elongate shaft to pass therethrough, but preventing passage of the head therethrough.

Abstract: A surgical screw assembly is provided that includes a fastener including an elongate shaft having a proximal end and a distal end and a head at the proximal end. A tulip having an internal bearing surface and a distal end having a bore therethrough is provided to allow the distal end of the elongate shaft to pass therethrough. A first step feature located at a distal end portion of the bore and extending inwardly therefrom reduces the diameter of the bore to allow the distal end of the elongate shaft to pass therethrough, but prevents passage of the head therethrough. A second step feature located at a distal end portion of the bore, distally of the first step feature, further reduces the diameter of the bore to a dimension less than a dimension established by the first step feature, the further reduced dimension allowing the distal end of the elongate shaft to pass therethrough, but preventing passage of the head therethrough.

Abstract: Uniplanar surgical screw assemblies described include: a fastener including an elongate shaft; a saddle-shaped tulip having a tulip having a bore therethrough dimensioned to allow the distal end of the elongate shaft to pass therethrough, but to prevent passage of the head therethrough; and one or more features for limiting angular movement of the shaft, relative to the tulip, to one plane.

Abstract: A surgical screw assembly including: a fastener including an elongate shaft having a proximal end and a distal end and a head at the proximal end. A tulip having a an internal bearing surface is provided. A distal end of the tulip has a bore therethrough defining the internal bearing surface. Locking enhancement features are configured to cooperate with the head, such that, in an unlocked configuration, the head is movable relative to the tulip; in a provisionally locked configuration, the locking enhancement features engage the head with a first polyaxial grip strength; and in a finally locked configuration, the locking enhancement features engage the head with a second polyaxial grip strength greater than the first polyaxial grip strength.

Abstract: Methods and devices are provided for spinal fixation. In one exemplary embodiment, the methods and devices provide one or more points of fixation located adjacent to a first fixation point at which a bone anchor is implanted in bone. For example, an extension member can be coupled, either directly or indirectly, to a bone anchor, and a fastener can be used to anchor the extension member to bone at a second point of fixation adjacent to the first point of fixation. The second point of fixation can be effective to prevent rotation or other movement of the bone anchor, thereby stabilizing the bone anchor. The methods and devices are particularly useful for unilateral fixation, in which one or more levels of the spine are stabilized along a single lateral side of the spine.

Abstract: Methods and devices are provided for spinal fixation. In one exemplary embodiment, the methods and devices provide one or more points of fixation located adjacent to a first fixation point at which a bone anchor is implanted in bone. For example, an extension member can be coupled, either directly or indirectly, to a bone anchor, and a fastener can be used to anchor the extension member to bone at a second point of fixation adjacent to the first point of fixation. The second point of fixation can be effective to prevent rotation or other movement of the bone anchor, thereby stabilizing the bone anchor. The methods and devices are particularly useful for unilateral fixation, in which one or more levels of the spine are stabilized along a single lateral side of the spine.