A spinal screw assembly is provided. The assembly may be provided with a screw and a movable head in which angulation of the screw relative to the movable head is constrained so that angulation within limits is allowed in one plane but lesser or no angulation is allowed in another plane. Methods to assemble the disclosed apparatus are also disclosed.

An orthopedic fixation device for affixing the screw head of a polyaxial pedicle screw has a tulip, a saddle, and a ring. The tulip has an interior cavity and two opposed threaded arms and a lower ledge. The saddle is inserted into the tulip body, and has a U shaped groove for receiving a spinal fixation rod. The ring has a diameter that is smaller than the widest diameter of the screw head, and is formable into a diameter larger than the widest diameter of the screw head when the screw head is pushed into the ring. The ring has a connection portion that mates with a connection portion of the saddle. The screw head is clamped within the tulip body between the saddle and the ring when a cap is threaded between the tulip arms.

Devices and methods for enhancing the effectiveness of spinal stabilization, and particularly that of cervical spinal stabilization, are provided herein. More specifically, methods and systems are disclosed for effectively positioning occipital plates and spinal fixation assemblies within target vertebrae, while also reducing any associated patient trauma (e.g., muscle stripping, tissue damage, etc.). The systems and methods can utilize trans-lamina delivery of the spinal fixation assemblies to allow for the positioning of the fixation elements along the midline of the patient's spine.

The present invention is generally directed to orthopedic fixation devices that comprise a coupling element and a bone fastener, whereby the bone fastener can be loaded into the coupling element through the bottom of a bore in the coupling element. The orthopedic fixation devices described herein can include modular locking clamp assemblies that can be fixed onto fasteners that are already implanted in bone. The modular locking clamp assemblies can include polyaxial locking clamp assemblies, as well as monoaxial locking clamp assemblies.

The present invention is broadly directed to a modular pedicle screw assembly 10 for immobilisation and stabilisation of spinal segments in a patient (not shown). The modular pedicle screw assembly 10 generally comprises a bone screw 12, a uniaxial inner collet 14 arranged to cooperate with a head 16 of the bone screw 12, a seat 18 arranged to provide seating for retention of the inner collet 14, and an inner collet actuator 20 designed to engage the seat 18 to activate the inner collet 14 for clamping about the head 16 of the bone screw 12.

A receiver subassembly adapted to couple with the capture portion of a bone anchor or shank to form a pivotal bone anchor assembly. The receiver subassembly includes a receiver having cavity above a distal opening sized and shaped for bottom loading the capture portion there-through, with the cavity configured to support both a split ring retainer and second split ring above of the spit ring retainer within the receiver. The receiver subassembly further includes an insert positionable in the receiver above the split rings and configured for downward deployment by tooling to engage the capture portion of the bone anchor. The split ring retainer is configured to expand around and close below the capture portion of the bone anchor upon an uploading of the capture portion into the cavity, so as to capture the capture portion within the cavity with the bone anchor extending downward through the distal opening.

A spinal screw assembly is provided. The assembly may be provided with a screw and a movable head in which angulation of the screw relative to the movable head is constrained so that angulation within limits is allowed in one plane but lesser or no angulation is allowed in another plane. Methods to assemble the disclosed apparatus are also disclosed.

A pivotal bone anchor assembly includes a shank having a shank head with a partial spherical shape at a proximal end and an anchor portion opposite the shank head for fixation to the bone of a patient. The assembly also includes a receiver having an upper portion defining a channel for receiving an elongate rod and a base defining a cavity in communication with the channel and with a bottom surface of the receiver through a distal opening. The assembly further includes a retainer positionable into non-rotatable and non-pivotal engagement with an inner surface of the cavity prior to the shank head being received within the cavity, with the retainer having a central opening configured to receive and capture the shank head within the cavity while allowing for pivotal motion between the shank and the receiver in at least one plane, and with a lower portion of the retainer extending below the bottom surface of the receiver.

A coupling device for use with a bone anchoring element includes a receiving part having first and second ends, a longitudinal axis, and a coaxial passage, and a pressure member having a first portion and an expandable portion connected axially to the first portion forming a seat for the head. The pressure member is movable to a position where the receiving part acts on the expandable portion to clamp the head in the seat. The seat can be asymmetric relative to the longitudinal axis while a central axis of the first portion is coaxial with the longitudinal axis, such that the seat facilitates pivoting of the bone anchoring element in a first direction to a first maximum angle and in an opposite direction to a second maximum angle smaller than the first maximum angle.

A pivotal bone anchor assembly includes a shank having an anchor portion and a head with a partially spherical outer surface, a drive socket, an annular planar top surface surrounding the drive socket, and a frusto-conical surface between the planar top surface and the partially spherical outer surface. The assembly further includes a receiver having a base defining an axial bore and an upper portion defining a channel configured to receive a rod, and an insert positionable within the axial bore having an upper surface engageable with the rod, a lower surface for transferring a downwardly-directed force toward the head, and a central aperture for accessing the drive socket, with the rod extending across the central aperture when the fixation rod is engaged by the upper surface. After the head, the insert, and the rod are positioned in the receiver, the frusto-conical surface remains spaced apart from the rod to in all pivotal orientations of the shank relative to the receiver.