Polyaxial bone anchor with helical capture connection, insert and dual locking assembly
OwnerRoger P. Jacksoninventor
Life of this patent
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Abstract
A medical implant assembly includes a polyaxial bone anchor having a shank, a receiver, a lower compression insert with surfaces for closely receiving an elongate connecting member and a dual closure structure that may include a single flange or helical flange. The dual closure structure independently engages the connecting member and the lower compression insert. A threaded capture connection of the bone anchor includes a shank upper surface exclusively engaging the lower compression insert and a retainer threadably attached to the shank and spaced from the upper surface, the retainer configured for polyaxial motion with respect to the receiver prior to locking.
Claims1
In a medical implant assembly having at least one polyaxial bone screw with a shank, the polyaxial screw attached to a longitudinal connecting member, the improvement comprising:
- a) a lower compression insert disposed in a receiver of the bone screw, the lower compression insert having a seating surface for the longitudinal connecting member, a bottom surface and first and second upstanding arms, the arms operatively receiving the longitudinal connecting member, the bottom surface in direct engagement with the polyaxial bone screw shank;
- and
- b) a two-piece closure having an outer fastener and an inner set screw, the outer fastener directly engaging the first and second arms of the lower compression insert and independently locking the shank with respect to the receiver, the outer fastener having an outer flange in interlocking engagement with a flange track of the receiver, the inner set screw biasing the longitudinal connecting member toward the lower compression insert seating surface.
Dependencies are inferred from the claim text.