An anchor assembly can be couplable to a bone and can include an anchor and a housing. The anchor can include a shank securable to bone and a head coupled to a proximal portion of the shank. The housing can include a proximal portion including an anchor bore and a distal portion including a secondary bore configured to engage the anchor to limit angulation of the anchor relative to the housing.

A surgical connection device for a spine is disclosed including a stabilization member, compression arms and traction arms, the device being used in conjunction with first anchor points fixed to vertebrae at a first lateral side of the spine and second anchor points fixed to vertebrae at a second lateral side of the spine. A first spinal rod may be attached to the first anchor points and a second spinal rod may be attached to the second anchor points. The compression arms connect the stabilization member to the first and second anchor points or rods and bear compressive forces. The traction arms connect the stabilization member to the first and second anchor points or rods and bear tensile forces. Application of both tensile and compressive forces via the device may serve to straighten, change a direction of bending or increase a degree of bending of the rods and/or spine. The use of the traction arms may also provide for a more flexible construct.

This application describes a spinal fixation system. The spinal fixation system includes at least a rod member having shaped ends, at least two pedicle screws capable of receiving the shaped ends of the rod member, and a system for introducing the rod member and pedicle screws in a minimally invasive fashion.

A polyaxial bone anchoring system comprises a bone anchoring member provided with a hemispherical head and a tubular barrel comprising a base traversed by an axial channel of which the cross-section is greater than the cross-section of the hemispherical head, the channel having, in the lower part, a frustoconical housing that widens in the direction opposite the hemispherical head and, upstream from the frustoconical housing, a transverse shoulder of which the inner cross-section is substantially equal to the cross-section of the hemispherical head, the system further comprising a conical split ring of which the outer surface matches the inner surface of the frustoconical housing and of which the minimum cross-section when idle is smaller than the nominal cross-section of the hemispherical head, said ring being made from a deformable material.

A bone fixation system with variable z-axis translation is provided. The system includes an outer tulip coupled to a bone fastener via a screw retainer. An inner tulip is coupled to the outer tulip such that the inner tulip is longitudinally movably relative to the outer tulip. The inner tulip includes a lock that provides a seat for a connecting rod. The inner tulip together with a seated rod is permitted to translate along the z-axis inside the outer tulip when in an unlocked position. Also in the unlocked position, the bone fastener is free to angulate relative to the outer tulip. The z-axis position of the inner tulip and rod relative to the outer tulip is fixed in a locked position. Also, in the locked position, the bone fastener is locked with respect to the outer tulip. The system may be adjusted between the locked and unlocked positions by way of a set screw.

Minimally invasive methods and devices for introducing a spinal fixation element into a surgical site in a patient's spinal column are provided. In general, the method involves advancing a spinal fixation element in a first, lengthwise orientation along a pathway extending from a minimally invasive percutaneous incision to a spinal anchor site. As the spinal fixation element approaches the spinal anchor site, the fixation element can be manipulated to extend in a second orientation, which is preferably substantially transverse to the first orientation, to position the fixation element in relation to one or more spinal anchors.

A polyaxial bone anchoring device includes: an anchoring element having a shaft for anchoring in a bone and a head, the head having a spherically-shaped outer surface portion; a receiving part configured to be pivotably connected to the head, the receiving part having a top end and a bottom end, a longitudinal axis extending through the top end and the bottom end, a channel transverse to the longitudinal axis for receiving a rod, and an accommodation space for accommodating the head, the accommodation space having a lower opening at the bottom end, a sleeve-like insert piece configured to be positioned around a portion of the head and to pivot in the receiving part, the insert piece having a spherically-shaped outer surface portion, wherein a lower edge of the insert piece extends past the lower opening in a direction away from the receiving part when the insert piece is seated in the receiving part in a position in which a central axis of the insert piece is coaxial with the longitudinal axis, and wherein the insert piece has an opening with a diameter greater than or equal to a maximum diameter of the head when the head is not in contact with the insert piece; a pressure member configured to be arranged at least partially in the accommodation space, the pressure member having a lower surface portion configured to contact the head to exert pressure onto the head when the head and the pressure member are arranged in the receiving part; wherein when the head, the insert piece, and the pressure member are arranged in the receiving part, the insert piece is tiltable with respect to the longitudinal axis of the receiving part and with respect to a longitudinal axis of the anchoring element, and wherein the anchoring element and the insert piece can be locked at respective angles relative to the longitudinal axis of the receiving part by exerting pressure with the pressure member onto the head.

A bone anchoring device includes an anchoring element having a shaft and a head, a receiving part having a coaxial bore and a seat for receiving the head, a pressure element configured to be movable within the bore, and a preload element being positionable between the head and the pressure element. When the head is inserted in the receiving part, the head is pivotable with respect to the receiving part, and can be locked at an angle relative to the receiving part by the pressure element. The pressure element can assume a position relative to the receiving part where the pressure element and the preload element are in direct contact, and where the pressure element exerts a force onto the head via the preload element to maintain one of a plurality of releasable angular positions between the head and the receiving part by friction before locking the head.

A pivotal bone anchor assembly includes a receiver with an axial bore communicating with a bottom of the receiver through a bottom opening, a circumferential locking groove adjacent the bottom opening, a circumferential expansion groove above the locking groove with a diameter that is greater than the diameter of the locking groove, and a transition surface between the locking groove and the expansion groove. The assembly also includes an insert uploadable through the bottom opening, an open retainer ring uploadable through the bottom opening after the insert and positionable within the locking groove, and a shank having a shank head. An upward loading motion of the shank head through the bottom opening urges the open retainer ring up into expansion around the shank head within the expansion groove, after which the open retainer ring resiliently returns to the locking groove, with a bottom surface of the open retainer ring seated against an upwardly-facing seating surface and a top surface extending above the level of the transition surface into the expansion groove, so as to capture the shank head of the shank within the axial bore of the receiver.

A polyaxial bone screw assembly includes a threaded shank body having an integral upper portion receivable in an integral receiver, the receiver having an upper channel for receiving a longitudinal connecting member and a lower cavity cooperating with a lower opening. A friction fit compression insert (some with lock and release feature), a planar split retaining ring and a shank upper portion cooperate to provide for pop- or snap-on assembly of the shank with the receiver either prior to or after implantation of the shank into a vertebra. The shank and receiver once assembled cannot be disassembled and the receiver and insert may include aligned tool receiving apertures for lock and release of the polyaxial mechanism.