Connection assembly for spinal implant systems

#Spinal implant systems provide a rod for supporting and positioning the spine in response to the specific problem being corrected by the implant and the patient's particular anatomy. The systems comprises a support rod, bolts secured to vertebrae and a connector that securely engages the support rod to the connecting bolts and allows the system to assume positions where the rod is maintained at various angles in response to the problem being corrected and the patient's particular anatomy. Although implant systems currently available satisfy these basic needs, further refinements are needed in the design of the connection assemblies utilized. Connection assemblies are needed that: minimize the assembly preparation prior to installation; can quickly assume and maintain an approximate position in the initial phase of installation, then be quickly and easily locked into position to complete the installation; have the ability to be repositioned with minimal effort after initially secured; and require minimal space in the patient's spinal region for installation.

#It is one object of the present invention to provide a connection assembly for a spinal implant system having components that limit the rotation of a spinal implant rod in respect to a corresponding spinal implant bolt, cause the initially implanted system to assume and maintain a position that approximates its final position and allow the system to be easily secured when the appropriate position has been attained. The structure limiting rotation is an interface element having an internal stop within an internal circumference or internal periphery, the internal stop positioned to contact other internal structures such as two edges of a seat maintaining a second interface element. The nature of the internal stop and its placement allow the connection assembly's size to be reduced without sacrificing the assembly's performance.

#In one aspect of the present invention, a connection assembly for connecting a spinal implant rod to a spinal implant bolt is provided, the assembly comprising: a rod connecting member having an opening for receiving a portion of the rod, and a first interface element on the rod connecting member; a bolt connecting member attached to the rod connecting member, the bolt connecting member having an opening for receiving a portion of the bolt, and a second interface element on the bolt connecting member; the first interface element being fixed against rotation relative to the rod connecting member and the second interface element having a disengaged condition wherein the rod connecting member and bolt connecting member are rotatable within a limited range relative to one another, the limited range defined by an internal stop element positioned within an inner periphery of one of the interface elements; and the first interface element and the second interface element having an engaged condition wherein the rod connecting member and bolt connecting member are fixed against rotation relative to one another. Connection assemblies according to this embodiment of the present invention have structural features that provide for reduction in the assembly's size, that allow the assembly to approximate a final installed position early in the installation process while the assembly's interface elements are in a disengaged condition and allow the assembly to be quickly and easily secured to maintain an appropriate position once the elements assume an engaged condition.

#FIG. 1 is a plan view of a connection assembly for a spinal implant device according to the illustrated embodiment of this invention.

#FIG. 2 is a plan view in exploded form.

#FIG. 3 is a front elevation view.

#For the purposes of promoting an understanding of the principles of the invention, reference will now be made to the embodiment illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended, such alterations and further modifications in the illustrated device, and such further applications of the principles of the invention as illustrated therein being contemplated as would normally occur to one skilled in the art to which the invention relates.

#In the illustrated embodiment of the present invention there is provided a connection assembly of reduced size for a spinal implant assembly having interface elements that utilize internal structures to limit rotation of a spinal implant rod in respect to a spinal implant bolt, cause the implant assembly to assume and maintain an initial position approximating its final position, and allow the assembly to be easily secured to maintain the system in an appropriate position. There are shown in FIGS. 1 and 3, views of an assembled connection assembly 10 according to the illustrated embodiment. Corresponding exploded views are shown in FIGS. 2 and 4 illustrating internal details of selected components. The assembly comprises a rod connecting member 12 and a bolt connecting member 22. The rod connecting member 12 has an aperture 14 for receiving a spinal implant rod and a threaded aperture 32 for receiving a securing member such as the set screw for urging the rod within the aperture 14. The bolt connecting member 22 has an aperture 24 for receiving a spinal implant bolt or screw.

#The rod connecting member 12 and the bolt connecting member 22 are attached through a rotatable connection. The rotatable connection can be of any suitable design provided the connection is maintained while allowing the rotation of one member relative to the other. Suitable designs include a bolt connecting member 22 having a male protrusion 27 symmetrical about its long or connection axis 13 and a rod connecting member 12 having a female cavity 19 (FIG. 16) for receiving and engaging the male member. In a preferred embodiment, the male and female connections are provided by threaded members such as a screw 30 a threaded female cavity 20 (FIG. 13). Alternatively, the male and female connections could be provided by other suitable male and female connections capable of rotation and simple assembly such as snap-together connections. Connection would occur upon inserting the male protrusion with a flared end portion into the female cavity having a region to accept and retain the flared end portion of the male protrusion.