Abstract: A fastener cartridge installs clamping fasteners, e.g., a set screw and a lock nut, to fix a linking rod or cable in the head of an anchor assembly. The cartridge carries one or more fasteners, or pairs of inner and outer fasteners, and applies them onto the anchor head without cross-threading. A separate holder mechanism aligns and guides the cartridge with a centering body into which the fastener cartridge fits. One cartridge has a box wrench that externally grips and turns the nut, and a central shaft coaxial with the box wrench that positions and rotates a clamp screw in coordination with the nut. Preferably, these are configured, by springs, detents or offset positioning surfaces, to install the inner lock screw coaxially with but ahead of the outer nut to fix a linking member anchor assemblies prior to fitting, e.g., compressions and distractions of the spine and final tightening.

Abstract: A fastener cartridge installs clamping fasteners, e.g., a set screw and a lock nut, to fix a linking rod or cable in the head of an anchor assembly. The cartridge carries one or more fasteners, or pairs of inner and outer fasteners, and applies them onto the anchor head without cross-threading. A separate holder mechanism aligns and guides the cartridge with a centering body into which the fastener cartridge fits. One cartridge has a box wrench that externally grips and turns the nut, and a central shaft coaxial with the box wrench that positions and rotates a clamp screw in coordination with the nut. Preferably, these are configured, by springs, detents or offset positioning surfaces, to install the inner lock screw coaxially with but ahead of the outer nut to fix a linking member anchor assemblies prior to fitting, e.g., compressions and distractions of the spine and final tightening.