| 摘要 |
A bone plate is formed with a throughgoing hole formed with a radially inwardly open outer groove. A screw fastener has a shaft engageable coaxially through the hole and a head of larger diameter than the shaft and adapted to bear axially on the plate around the hole. The shaft is formed offset from the head with a radially outwardly projecting ridge defining a radially outwardly open inner groove aligned radially with the outer groove when the fastener is fitted through the hole with the head bearing on the plate. An elastically deformable ring of a diameter generally equal to that of the hole at the outer groove is formed with at least one radially inwardly directed projection that, when the ring is fitted to the outer groove and the fastener is seated in the hole, projects radially inward into the inner groove of the fastener.
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