NZ731795A - Spinal implant assembly - Google Patents

Abstract

A spinal implant assembly 10 comprising an intervertebral device 20 configured to be installed in a spinal disc space. The intervertebral device 20 has a head 20a and a body 20b. The spinal implant assembly 10 further comprises a coupling body 40 for coupling the head 20a of the intervertebral device 20 and an elongate member 30. The coupling body 40 and head 20a each have a longitudinal axis. The head 20a can be received by the coupling body 40 with the longitudinal axis of the head 20a at a selected angle within a predetermined range of angles relative to the longitudinal axis of the coupling body 40. At least part of the body 20b is tapered and externally threaded. The body 20b is configured to cause vertebral distraction when inserted in the disc space between adjacent vertebrae or at the lumbo-sacral joint, with the threads cutting into bone on either side of the spinal disc space as the body component is inserted in the disc space. The head 20a has a head portion 51 and a shank 53. The shank 53 is at least partially externally threaded. The body 20b has a bore with a first open end, the bore being at least partially internally threaded, the internal threads of the bore corresponding with the external threads of the shank portion of the head component such that the head component is releasably attachable to the body component. The head portion 51 of the head 20a is at least partially spherical. The coupling body 40 comprises a hollow tubular body with a proximal end and a distal end, with the head portion 51 of the head 20a being receivable in the hollow tubular body. The coupling body has a first opening in the distal end and a second opening in the proximal end, with the first opening being larger in diameter than that of the head portion 51 and the second opening being smaller in diameter than that of the head portion 51. The first opening is large enough to receive the head portion 51 of the head 20a therethrough, and the second opening is sized such that the shank portion 53 of the head 20a. A portion of the inner surface of the coupling body 40 has a concavely curved inner surface, with the curved inner surface corresponding with the at least partially spherical head portion 51, such that the head component butts up against the curved inner surface and may be positioned polyaxially relative to the coupling body when assembled. The body 20b of the intervertebral device has a hollow bore, with the shank 53 of the head 20a component being insertable within the bore. The shank 53 of the head 20a is shorter in length than the hollow bore of the body component such that with the shank 53 fully inserted in the body 20b, at least some hollow space in the hollow bore remains unoccupied by the shank 53. The body 20b has at least one aperture communicating with the hollow bore.