Importance

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Abstract

An orthopaedic junction or anchor assembly for anchoring a linkage such as a rod or cable used for fixation or reduction. The assembly includes a slotted bolt that fits through an apertured plate, and a support platform that fits over the bolt, capturing the plate in a one-piece assembly for convenient installation. The base of the bolt is recessed in the plate and a cap or nut tightens down to secure the linking member, e.g., a rod or cable, in the bolt slot, simultaneously clamping the bolt to fix both its position and its orientation on the plate. The support platform has the form of a generally annular washer with an upper surface including a transverse groove on which the rod seats, and a lower surface abutting the plate. A sleeve potion may extend within and buttress the surrounding wall of the plate. The plate may take various forms, such as a hook or offset arm, an occipital T-plate, or a vertebra plate. In one embodiment the support platform is swaged to the bolt, allowing the bolt to rotate freely, and slide along the slot of the bone plate as a captive assembly, keeping all the components together without constraining the alignment during installation. Other embodiments employ mating ridge and groove, or other detents circumferentially on the bolt shaft and the inner face of the support, to snap and retain the pieces together. When the rod or other linkage has been positioned, a lock nut or cap then fastens onto the bolt to seat the rod against the support platform and lock both the position of the bolt and the angular orientation of its slot. Tightening the nut or cap pushes the rod downward to seat on the support plate and pulls the bolt upward to press the base of the bolt against the bottom of the plate. The bottom surfaces of the support washer as well as the plate-facing surface of the base may be roughened or textured to engage the plate, or otherwise increase resistance to rotational and lateral movement once the rod has been positioned and the nut is torqued down.

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First Claim