| 主权项 |
1. A bone fixation assembly comprising:
a multiplicity of screws, each having a threaded section with a tip at a first end and a head having an upper surface at a second end, the head having a first diameter where it meets the threaded section and a larger diameter at the upper surface; and a head height between the two diameters; a plate having a plane and having an upper surface, a lower surface, and a multiplicity of screw bores therethrough, the screw bores having an upper opening having a first diameter and a lower opening having a second diameter and a screw bore height between the two diameters, the plate having a retainer arm recess floor defining a retainer arm recess floor plane, the retainer arm recess floor above the walls defining the screw bore, the plate having a multiplicity of pin bores therethrough, such that each screw bore has a pin bore adjacent thereto; and a single retainer arm with a first end having a depending pin for engaging the pin bore of the plate adjacent each screw bore and a removed end with a body therebetween, the removed end not attached to the plate and free to move in the plane of the retainer arm recess floor such that in a first position part of the retainer arm body blocks some of the upper opening of the screw bore and in a second position, responsive to contact with a screw head as the screw head rotates and moves longitudinally into a screw bore, moves to a second, loaded position outward from the first position, and with further longitudinal movement of the screw such that the upper surface of the screw head passes below the upper opening of the screw bore, substantially returns to the first position. |
