Apparatus and method for measuring spinal instability
First Claim
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1. An apparatus for measuring instability of a motion segment unit of a spine comprising:
- distraction means for applying a force to and thereby separate adjacent vertebrae of the motion segment unit at a constant rate;
detection means connected to said distraction means for measuring the resistance of the adjacent vertebrae to said distraction, at a plurality of force-exerting positions, said detection means generating an output signal corresponding to said resistance;
translation means adapted to receive said output signal from said detection means and for translating said output signal into interpretable data corresponding to the relative stiffness of the motion segment unit; and
safety means operatively engaged when the resistance of the adjacent vertebrae to the distraction generated by the distraction means reaches a predetermined level.
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Abstract
An apparatus and method for measuring spinal instability provides a vertebrae distractor having a pair of distractor arms driven by a motor which separate adjacent vertebrae of a motion segment unit of the spine at a constant rate of distraction up to a predetermined maximum force and measuring the resistance of the adjacent vertebrae to the force. The changes in the resistance to distraction are detected and recorded. The data thus provided is then compared to predetermined standards. A determination concerning further treatment of the subject patient may be based upon the results obtained.
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Citations
22 Claims
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1. An apparatus for measuring instability of a motion segment unit of a spine comprising:
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distraction means for applying a force to and thereby separate adjacent vertebrae of the motion segment unit at a constant rate; detection means connected to said distraction means for measuring the resistance of the adjacent vertebrae to said distraction, at a plurality of force-exerting positions, said detection means generating an output signal corresponding to said resistance; translation means adapted to receive said output signal from said detection means and for translating said output signal into interpretable data corresponding to the relative stiffness of the motion segment unit; and safety means operatively engaged when the resistance of the adjacent vertebrae to the distraction generated by the distraction means reaches a predetermined level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 21, 22)
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20. A method of measuring instability of a motion segment unit of a spine, comprising:
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(a) placing distraction means between adjacent vertebrae; (b) moving said distraction means from a relaxed position exerting no force on the adjacent vertebrae to a plurality of force exerting positions in a manner in which the adjacent vertebrae are distracted at a constant rate; (c) detecting the resistance of the adjacent vertebrae to the force which is exerted and generating an output signal corresponding to the resistance of the adjacent vertebrae to said force; (d) terminating movement of the distractor means at a force exerting position when a predetermined maximum resistance by the adjacent vertebrae to said force is detected; and (e) converting said output signal into interpretable data which can be compared against predetermined standards.
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Specification