Composite material spinal implant
A pedicle screw implant construct kit, comprising at least one pedicle screw, at least one collar comprising a recess for receiving a rod, the collar configured to be coupled to a head of the pedicle screw, an elongated rod for connecting the collar to one more additional collars to couple between the pedicle screw and one or more additional screws, and a locking ring sized to be positioned over at least a distal portion of the collar to restrain relative movement of the screw head and rod by exerting radial compression force onto the collar. In some embodiments, the components of the kit are comprised of carbon reinforced composite material, optionally with no radiation blocking material. In some exemplary embodiments of the invention, the kit includes two locking rings on a collar, optionally both below the rod.
1. A pedicle screw implant construct kit, comprising:
at least one pedicle screw including a head, said screw comprising composite material including reinforcing filaments embedded in a polymer matrix;
a rod;
at least one collar, said collar comprising composite material including reinforcing filaments embedded in a polymer matrix, said collar including at least one recess defining a cavity for receiving said rod, said cavity defining a lumen including an end having a first cross-sectional profile and including a middle having a second cross-sectional profile, said first cross-sectional profile larger than said second cross-sectional profile, said first cross-sectional profile being between 1% to 10% larger than said second cross-sectional profile;
said collar sized, shaped and configured to be coupled to said head of said pedicle screw;
said rod being an elongated rod sized and shaped for connecting said collar to one or more additional collars, thereby coupling between said at least one pedicle screw and one or more additional screws, said rod comprising composite material including reinforcing filaments embedded in a polymer matrix; and
at least one restraint, said restraint comprising composite material including reinforcing filaments embedded in a polymer matrix, said restraint sized and shaped to be positioned over at least portion of said collar and restrict relative movement of one or both of the screw head and the rod relative to said collar, by exerting radial compression force onto said collar.
2. A kit according to claim 1 , wherein said kit is less than 1% by weight atoms with an atomic number over 25.
3. A kit according to claim 1 , wherein said lumen in which said rod is received is rotationally asymmetric.
4. A kit according to claim 3 , wherein said first cross-sectional profile includes an elongation in a direction radial to a longitudinal axis of said lumen.
5. A kit according to claim 4 , wherein said elongation is different at said ends of said lumen from any elongation at a center of said lumen.
6. A kit according to claim 4 , wherein said elongation support the engagement by said cavity of both straight rods and rods bent with a radius of curvature of at least 30 mm.
7. A kit according to claim 4 , wherein said elongation is vertical with respect to a long axis of said collar.
8. A kit according to claim 1 , wherein said restraint is mounted in a narrowing in an outer profile of said collar, vertically adjacent to a gradual widening in said outer profile and is configured to lock to said widening by friction.
9. A kit according to claim 1 , comprising two restraints for said collar and wherein said collar includes two regions for locking of said restraints to said collar.
10. A kit according to claim 9 , wherein said collar includes at least one radial extension which prevents sliding off of at least one restraint from said collar.
11. A kit according to claim 9 , wherein said collar is shaped so that locking one restraint only restricts the movement of one of said rod and said head of said screw.
12. A kit according to claim 9 , wherein said collar is shaped so that locking of the two restraints requires movement of the two restraints in a same direction or instead in opposite directions.
13. A kit according to claim 9 , wherein said two restraints are mounted below said rod.
14. A kit according to claim 1 , wherein said collar is shaped so that a restraint can be mounted thereon without said restricting and then locked without extending during a mounting state nor during a locking state more than 1 mm below said collar.
15. A kit according to claim 14 , wherein said collar is shaped so that said restraint locks by a distal movement away from said cavity in which said rod is received and from a cavity in which said screw head is received.
16. A kit according to claim 1 , wherein said rod is curved, having a bending radius of between 30-240 mm.
17. A kit according to claim 1 , wherein said first cross-sectional profile defines a widening extending between 10-90% of a length of said lumen.
18. A kit according to claim 1 , wherein when said rod is received within said lumen it contacts the walls of said lumen at an approximate center of said lumen.
19. A kit according to claim 1 , wherein said lumen flares towards said ends of said lumen.
20. A kit according to claim 1 , wherein said collar is comprised of a unitary, single piece body.
21. A kit according to claim 1 , wherein said end includes a widening radially away from said lumen, said widening being 1% to 10% wider than said rod.
22. A kit according to claim 1 , wherein said lumen includes a widening at either end relative to a center of said lumen, each said widening being between 1% to 10% wider than a cross-sectional profile of a rod received within said lumen.
23. A kit according to claim 1 , wherein said restraint comprises a locking ring.