A reducer comprises a reducing shaft for engaging a stabilization member, a reducer body for engaging a pedicle screw extender and receiving the reducing shaft along an axis, and one or more of a three-pawl clutch mechanism, a three-stage locking mechanism and a closure mechanism. The clutch mechanism comprises a clutch housing comprising a central passage into which the reducing shaft extends and ports intersecting the central passage, a clutch knob surrounding the clutch housing, and clutch pawls disposed within the ports. The locking mechanism attaches the reducer body to the pedicle screw extender and comprises a first pivoting lever comprising a toothed end, a second pivoting lever comprising a socket for engaging the tooth, and a protrusion configured to engage the pedicle screw extender. The closure mechanism comprises a driver shaft extending through the reducing shaft and a biasing element to bias the driver shaft to a retracted position.

Systems and methods of operating a tower extender in conjunction with a bone anchor housing can comprise positioning a plurality of deflectable members of a distal end of the tower extender proximate the bone anchor housing, pushing the distal end of the tower extender into engagement with the bone anchor housing to flex the plurality of deflectable members around the bone anchor housing to attach the tower extender relative to the bone anchor housing, rotating a knob to lock the plurality of deflectable members from deflecting away from the bone anchor housing, performing a portion of a surgical procedure with the tower extender, rotating the knob to deflect the plurality of deflectable members away from the bone anchor housing and puling the tower extender away from the bone anchor housing.

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 provide for increased articulation of the shank relative to the receiver.

A posterior spinal fusion system may include a plurality of cannulas that mate with cages polyaxially coupled to pedicle screws. The cannulas maintain access to the pedicle screws to facilitate percutaneous insertion of a fusion rod into engagement with the cages. Each cannula has a pair of blades that may be held together by an abutment member that at least partially encircles the blades. Each abutment member abuts the skin to define a variable subcutaneous length of the corresponding cannula. Each abutment members is also lockably removable from the corresponding blades to enable the blades to pivot with respect to the connecting element to a position in which they can be withdrawn from the connecting element. The blades of each cannula are spaced apart to provide first and second slots of each cannula, through which the fusion rod can be percutaneously inserted.

A load sensing assembly for a spinal implant includes a set screw having a central opening that extends from a first end of the set screw toward a second end of the set screw. The second end of the set screw is configured to engage with an anchoring member. The load sensing assembly includes an antenna, an integrated circuit in communication with the antenna, where the integrated circuit is positioned within the central opening of the set screw, and a strain gauge in connection with the integrated circuit. The strain gauge is located within the central opening of the set screw in proximity to the second end of the set screw.

A polyaxial bone screw assembly includes a threaded shank body having an upper portion, a receiver member or head, a retaining and articulating structure, and a pressure insert disposed between the shank upper portion and a rod. The receiver has a U-shaped cradle defining a channel for receiving a spinal fixation rod and a receiver cavity. The retaining and articulating structure attaches to the shank and rotates with the shank in the cavity during positioning. The pressure insert presses upon the shank upper portion and not the retaining and articulating structure.

Method for performing spinal correction surgery. The method includes creating at least one access opening in a patient, and implanting a plurality of anchor devices through the at least one access opening onto a plurality of corresponding vertebral bodies. Each anchor device has a channel defined therein. The method further includes disposing a tether into the channel of each of the plurality of anchor devices. A first end portion of the tether is secured to a first of the plurality of anchor devices. Additionally, the method includes translating the vertebral body corresponding to the selected anchor device using a pusher tool. Furthermore, the method includes applying a tension to the tether using a tensioner.

Devices, systems, and methods are provided for driving an implant and applying counter torque. For example, a driver can include a handle, a driver shaft, and a counter torque shaft, the counter torque shaft being laterally offset from the driver shaft. A distal end of each shaft can mate with a specific type of implant and/or anatomy. The shafts can be removed and replaced from the device, allowing a user to select shafts having particular lengths and/or mating tips. In use, distal ends of the shafts can be fixed or constrained relative to one another and to an implant such that the counter torque shaft cannot orbit around the driver shaft. Rotating the handle can rotate the driver shaft, driving the implant. This can cause the counter torque shaft to try to orbit around the driver shaft, but the fixed/constrained ends restrict this motion, applying the counter torque.

Surgical instruments and methods for delivering bone anchor assemblies into bone are disclosed herein. Use of these anchors or instruments can eliminate one or more of the steps in a conventional bone anchor installation procedure, improving surgical efficiency and safety. In general, a surgical instrument can include a handle assembly having an elongate shaft extending distally therefrom. The handle assembly can be configured to axially translate a stylet extending therethrough relative to a bone anchor assembly coupled to the elongate shaft, and it can be configured to move the stylet proximally in response to distal advancement of a bone anchor assembly into bone. The surgical instruments can include various mechanisms for adjusting the position of the stylet.

A method for securing an elongate rod to a bone anchor with a receiver and a threaded plug. The receiver includes a channel configured to receive the elongate rod, and a helically wound receiver guide and advancement structure formed into the interior surfaces of the receiver. The threaded plug is configured for positioning within the channel to secure the elongate rod to the receiver in a locked configuration, with the threaded plug having an outer surface with a mating continuous helically wound guide and advancement structure configured for rotatable engagement with the receiver guide and advancement structure.