Height-adjustable spinal implant and operating instrument for the implant
A height-adjustable implant for insertion between vertebrae, includes first and second sleeve parts which are rotationally fixed in coaxial alignment and interconnected in an axially displaceable manner. The first sleeve part has an internal thread. A nut is positioned coaxially in an inner space surrounded by the sleeve parts and is fixed to the second sleeve part so that it can rotate but is axially fixed. The nut has an external thread which engages in the internal thread of the first sleeve part. A toothed ring extends coaxially with the central longitudinal axis of the sleeve parts and is located on the nut. The second sleeve part has a radial access opening in the vicinity of the toothed ring.
1. A height-adjustable implant for insertion between vertebral bodies, the implant comprising:
a first sleeve part having an internal thread;
a second sleeve part;
said first and second sleeve parts:
being coaxially oriented about a central longitudinal axis;
being connected to one another in a rotationally fixed and axially displaceable manner;
having axially extending windows therein with mutually-facing, outwardly-open ends;
each adjacent two of said windows defining a respective circumferential section therebetween in each of said sleeve parts;
said circumferential sections of each one of said sleeve parts each fitting axially displaceably into a respective one of said windows of the other of said sleeve parts and defining an inner space of the implant, at least one of said circumferential sections of said second sleeve part having an access opening formed radially therethrough;
a nut disposed coaxially and circumferentially contained within said inner space and secured on said second sleeve part in a rotatable but axially fixed manner, said nut having an external thread engaging in said internal thread of said first sleeve part, said nut being secured on said second sleeve part with said external thread located outside said second sleeve part, as seen in an axial direction, said nut having an outer surface with an annular groove formed therein, said circumferential sections of said second sleeve part each have an inside face with a radially inwardly extending projection engaging in said annular groove of said nut; and
a toothed ring extended coaxially relative to said central longitudinal axis and disposed on said nut partially covering said access opening and on a side of said nut facing toward said second sleeve part, said access opening configured for receiving an operating instrument which cooperates with said toothed ring.
2. The implant according to claim 1 , wherein said toothed ring is constructed as a crown wheel of a contrate gear.
3. The implant according to claim 1 , wherein said toothed ring is disposed on a surface of said nut facing away from said external thread.
4. The implant according to claim 1 , wherein said circumferential sections have free ends, and said projections are disposed near said free ends.
5. The implant according to claim 1 , wherein said first and second sleeve parts each have an end face intended to bear on a vertebral body, and a respective support plate is secured on said end face of at least one of said sleeve parts.
6. The implant according to claim 5 , wherein said support plate is releasably secured on said end face.
7. The implant according to claim 6 , wherein said support plate is secured in a rotationally fixed manner on one of said sleeve parts.
8. The implant according to claim 7 , wherein:
said sleeve parts each have an end face and an inside face;
said end face of at least one of said sleeve parts has a plurality of circumferentially spaced-apart recesses formed therein opening into said inside face of said at least one of said sleeve parts; and
said support plate has projections complementary in shape to and engaging in said recesses.
9. The implant according to claim 5 , wherein said support plate is secured in a rotationally fixed manner on one of said sleeve parts.
10. The implant according to claim 9 , wherein:
said sleeve parts each have an end face and an inside face;
said end face of at least one of said sleeve parts has a plurality of circumferentially spaced-apart recesses formed therein opening into said inside face of said at least one of said sleeve parts; and
said support plate has projections complementary in shape to and engaging in said recesses.
11. The implant according to claim 1 , wherein said first and second sleeve parts have substantially the same diameter.
12. The implant according to claim 1 , wherein said respective circumferential sections have substantially the same wall thickness.