Spinal Derotation Instrument with Reduction Functionality
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Solution Overview
Problem
Conventional spinal deformity surgical procedures face challenges in correcting angular rotation of vertebrae due to stress on bone anchors, requiring separate instruments for derotation and reduction, which can lead to anchor failure or vertebral harm.
Innovation Solution
Instruments and methods that allow for the manipulation of bone anchors and spinal fixation elements without prior insertion of the spinal fixation element, enabling rotation and reduction in a single instrument, facilitating angular correction of vertebrae while minimizing stress on anchors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional derotation instruments are used after reduction, then the spinal fixation element can be secured to the bone anchor, but the bone anchors bind on the fixation element during rotation preventing motion or requiring significant force
Solution Approach 1:
The instrument allows derotation to be performed before reduction, meaning the vertebra can be rotated into correct alignment before the spinal fixation element is inserted and secured to the bone anchor. This preliminary derotation action prevents the binding problem that occurs when attempting to rotate after the fixation element is in place, as the rotation is performed when there is no fixation element to bind against the bone anchor.
2Adaptability or versatility
If separate instruments are used for derotation and reduction, then each function can be performed with specialized tools, but one instrument must be removed to allow the other to be used
Solution Approach 1:
The instrument combines both derotation and reduction functions into a single integrated device. The derotation mechanism and reduction mechanism are merged into one instrument that can perform both functions sequentially without requiring removal or exchange of instruments. This eliminates the need to remove one instrument to use another, while maintaining the specialized functionality of both derotation and reduction capabilities.
3Ease of operation
If vertebral rod derotation is performed with conventional procedures, then angular rotation can be corrected, but significant stress is placed on the interface between bone anchors and vertebra causing anchor failure or vertebral harm
Solution Approach 1:
The instrument performs derotation before reduction, meaning the angular correction is achieved before the spinal fixation element is inserted and secured to the bone anchor. This preliminary derotation reduces the stress on the bone anchor-vertebra interface because the rotation is performed when the fixation element is not yet constraining the bone anchor, thereby preventing anchor failure or vertebral harm that would occur with conventional post-reduction derotation.
Data Source
AI summary
Instruments and methods are provided for manipulating a bone anchor and a spinal fixation element. The instruments and methods disclosed herein are particularly suited to facilitate rotation of a bone anchor relative to another bone to correct the angular rotation of the vertebrae attached to the bone anchor. The instrument does not require the spinal fixation element to be inserted into the bone anchor prior to manipulation. The instrument further may be used in the insertion of the spinal fixation element into the bone anchor.