| 摘要 |
An orthopedic fixation device includes a fixation plate having at least one through hole in which a direction adjusting ring is held securely. The direction adjusting ring is provided with an inner threaded hole engageable with a second threaded portion of a double-threaded bone screw. Located at a lower portion of the double-threaded bone screw is a first threaded portion which is fastened onto a bone or vertebra. Located at the top end of the double-threaded bone screw is a head for urging and spreading a plurality of arresting edges located at the upper side of the direction adjusting ring so as to cause the direction adjusting ring to be retained securely in the round through hole of the fixation plate. The axis of the threaded hole of the direction adjusting ring forms with the axis of an outer ring body of the direction adjusting ring an angle ranging between 3 and 15 degrees.
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