A closed-head polyaxial screw for use in spinal instrumentation for spinal fusion, treatment of deformity, or the like. Polyaxial screws may have a two-part design, with the screw fitting into an aperture in the closed head. One or more clamps may secure the bone screw in the aperture. A closed-head polyaxial screw having a one part design is also disclosed. In addition, a one-part monaxial screw is described.

Bottom-loading bone anchor assemblies and components thereof are disclosed that have a reduced profile and can be utilized with bone screws of various size. Bone anchor assemblies of the present disclosure can include a receiver member, a drag retaining ring, and a shank. The retaining ring and shank can be inserted proximally into a bore of the receiver member. The drag ring can have a base and a walled portion extending proximally therefrom. The drag retaining ring can be disposed in a groove of the receiver member with the base forming a seat for the shank head that can hold the shank within the receiver. The walled portion of the drag retaining ring can impart a drag force on the shank head seated in the base to prevent unintended movement between the shank and the receiver member.

A compression fastener may include a shaft and a helical thread disposed about the shaft. The shaft may include a proximal end, a distal end, a proximal shaft portion, and a distal shaft portion. The helical thread may include at least one concave undercut surface and a plurality of pitches that may include at least one first pitch along the proximal shaft portion and at least one second pitch along the distal shaft portion. The at least one concave undercut surface may be angled towards one of the proximal end and the distal end of the shaft, and the at least one first pitch and the at least one second pitch may not be equal to each other.

A closed-head polyaxial screw for use in spinal instrumentation for spinal fusion, treatment of deformity, or the like. Polyaxial screws may have a two-part design, with the screw fitting into an aperture in the closed head. One or more clamps may secure the bone screw in the aperture. A closed-head polyaxial screw having a one part design is also disclosed. In addition, a one-part monaxial screw is described.

A bone implant may include a shaft having a proximal end, a distal end, a longitudinal axis, a proximal shaft portion, and a distal shaft portion. The proximal shaft portion may include a first minor diameter, and a first helical thread disposed about the proximal shaft portion defining a first major diameter. The first helical thread may include a first concave undercut surface. The distal shaft portion may include a second minor diameter, and a second helical thread disposed about the distal shaft portion defining a second major diameter. The second helical thread may include a second concave undercut surface. The first and second concave undercut surfaces may be angled towards the distal end of the shaft. The second minor diameter may be smaller than the first minor diameter and the second major diameter may be smaller than the first major diameter.

A method of preventing bone blowout may include forming a hole in a bone, the hole having a bone hole diameter, and inserting a bone fastener into the hole. The bone fastener may include a shaft having a minor diameter and a helical thread. The helical thread may be disposed about the shaft and may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft, and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. The minor diameter of the shaft may not be greater than 5% larger the bone hole diameter.

A pedicle bone fastener may include a shaft, a helical thread, and an integrated attachment feature. The shaft may include a proximal end, a distal end, and a longitudinal axis. The helical thread may be disposed about the shaft along the longitudinal axis between the proximal and distal ends of the shaft. The helical thread may include a first undercut surface and a second undercut surface. The first undercut surface may be angled toward one of the proximal end and the distal end of the shaft and the second undercut surface may be angled toward the other one of the proximal end and the distal end of the shaft. The integrated attachment feature may be disposed at the proximal end of the shaft and configured to be adjustably secured to a spinal stabilization implement.

Bottom-loading bone anchor assemblies and components thereof are disclosed that have a reduced profile and can be utilized with bone screws of various size. Bone anchor assemblies of the present disclosure can include a receiver member, a drag retaining ring, and a shank. The retaining ring and shank can be inserted proximally into a bore of the receiver member. The drag ring can have a base and a walled portion extending proximally therefrom. The drag retaining ring can be disposed in a groove of the receiver member with the base forming a seat for the shank head that can hold the shank within the receiver. The walled portion of the drag retaining ring can impart a drag force on the shank head seated in the base to prevent unintended movement between the shank and the receiver member.

The present disclosure generally relates to pedicle screws that can selectively lock polyaxial motion of a receiver head with a locking cap. The locking cap can allow locking of the polyaxial motion of the receiver member relative to the spherical head of the bone shank without having a rod placed in the rod slot of the receiver member. This can enable placement of the head of the pedicle screw in a desired position and orientation, locking the head in the desired position and orientation, and performing a maneuver, such as derotation, without a rod in place or any extra motion between the receiver member and the bone shank. In some embodiments, actuation of the locking cap can be achieved by rotating the locking cap relative to the receiver member, where rotation of the locking cap causes corresponding axial translation of the locking cap relative to the receiver member.

A bone anchoring device for anchoring and fixing vertebrae and for insertion into a pedicle canal is disclosed. A fork head having a U-shaped cut-out in a side view for a correction element, a connecting rod with two legs which terminate proximally and form a threaded section which engages with an adjusting means, wherein the legs have a radially outer circumferential area in which at least one retaining groove or other instrument attachment point is formed for gripping the fork head by a handling instrument, and a bone anchoring element with a proximal end facing away therefrom in the axial direction such that a distal direction and a proximal direction are also defined. The bone anchoring element has a spherical head at the proximal area, and the bone anchoring element is polyaxially pivotable with respect to the fork head, and has a pressure piece distally partially surrounds the bone anchoring element at the ball head, and proximally forms a seat for the connecting rod.