| 摘要 |
A multi-level polyaxial screw connection mechanism includes a bone fixation component and a head component directly connected to the bone fixation component. The head component includes a lower portion comprising at least one lower portion concave socket configured and an upper portion elevated compared with the lower portion. The upper portion comprises at least one upper portion concave socket configured and the lower portion(s) concave socket comprises a volume substantially equal to a volume of the upper portion(s) concave socket.
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