| 摘要 |
A polyaxial orthopedic device for use with rod implant apparatus includes a screw having a curvate head and a coupling element. The coupling element has a tapered lower portion including a slotted interior chamber in which the curvate head is initially polyaxially disposed. The coupling element further includes a recess for receiving the rod of the implant apparatus, and an exterior threading disposed on its upper portion which receives a locking nut. A locking ring is disposed about the lower portion of the coupling element, and provides an inward force on the outwardly tapered portion upon downward translation thereof, thereby causing the vertical slots to close, and crush locking the screw head within the interior chamber, thus eliminating the polyaxial nature of the screw-element coupling. In several embodiments a hollow cylindrical rod securing sleeve is provided which fits over the coupling element and locks the rod to the coupling element. In the other embodiments, the locking nut seats against the top of the rod, locking it in place.
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