| 主权项 |
1. A spinal distractor comprising:
a) a first element having an upper end portion, a lower end portion, and an intermediate portion having a first threaded hole threaded in a first direction, b) a second element having an upper end portion, a lower end portion and an intermediate portion having a second threaded hole threaded in a second opposite direction, c) a distance adjustment element threadably connected to each of the intermediate portions and comprising a threaded rod having a first end portion threaded in the first direction and a second end portion threaded in the second opposite direction, d) an upper component having a first end portion, a second end portion and an upper surface adapted for bearing against an upper vertebra, e) a lower component having a first end portion, a second end portion and a lower surface adapted for bearing against a lower vertebra,wherein the first end portion of the upper component engages the upper end portion of the first element and the second end portion of the upper component engages the upper end portion of the second element,wherein the first end portion of the lower component engages the lower end portion of the first element and the second end portion of the lower component engages the lower end portion of the second element,wherein each threaded hole threadably mates with the threaded rod so that i) the first and second element are separated by a first distance and ii) the upper surface of the upper component and lower surface of the lower component are separated by a second distance,wherein rotation of the distance adjustment element in a first direction causes the first distance between the elements to increase and the second distance between the upper surface of the upper component and lower surface of the lower component to increase, thereby causing distraction of the vertebrae,wherein a vertical force directed upward upon the upper component does not disengage the upper component from the first and second elements. |
