| 摘要 |
<p>A surgical implant, typically a cervical plate assembly, comprises a plate 10 having at least two apertures 11 and two screw threaded fastening devices 13 for securing the plate to bone. Each aperture in the plate has an annular groove 16 intermediate opposite ends of the aperture and each fastening device 13 comprises an outer screw 14 and an inner plug 15. The screw 14 has a head 18 at one end, a tip at the other end, an externally threaded shank 19 between the head and the tip and an internal bore 20 extending axially through the head and at least part way into the shank for receiving the inner plug. The head comprises a plurality of resiliently deformable fingers 22 separated by one another by axially extending slits 23. Each finger 22 has an outwardly projecting rib 24 extending circumferentially of the head intermediate opposite ends of the finger for snap fit engagement in the annular groove of a respective plate aperture. The inner plug is arranged so that when it is inserted into the internal bore of the screw it will prevent contraction of the head of the screw thereby preventing the ribs disengaging from the groove. <IMAGE></p> |
