Spinal Derotation Instrument Anti-Splaying Mechanism
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Solution Overview
Problem
Existing derotation instruments for spinal deformity correction face issues with splaying, where the extension tube arms disconnect from vertebral anchors when other instruments are inserted, interrupting surgical procedures.
Innovation Solution
The development of multifunctional derotation instruments with anti-splaying features, including longitudinal slots and pivot arms with biasing mechanisms, that prevent splaying and securely attach to vertebral anchors, allowing for derotation maneuvers, fixation element positioning, and access portals for other instruments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If extension tubes are used to apply derotation force to vertebral anchors, then derotation procedures can be performed, but the extension tube arms may splay and disconnect from the vertebral anchor when other instruments are inserted
Solution Approach 1:
The patent applies preliminary anti-action by incorporating biasing mechanisms (springs) that continuously exert a force to maintain the extension tube arms in their engaged position with the vertebral anchor. This pre-applied counteracting force prevents splaying before it can occur when other instruments are inserted into the extension tube, thus maintaining reliable attachment while allowing multifunctional use.
2Reliability
If the extension tube is made rigid to prevent splaying, then attachment stability improves, but the ability to apply derotation force through bending moments is reduced
Solution Approach 1:
The patent segments the extension tube structure into distinct functional zones: the arms are designed with controlled flexibility to engage and maintain attachment to the vertebral anchor, while the main body of the extension tube maintains sufficient rigidity to transmit derotation forces. This segmentation allows different parts of the same component to have different mechanical properties optimized for their specific functions.
Solution Approach 2:
The patent applies dynamics by incorporating biasing mechanisms that allow the extension tube arms to dynamically adjust and maintain engagement with the vertebral anchor while transmitting forces. The spring-loaded connection provides a dynamic system that can accommodate force application while maintaining stable attachment, rather than a static rigid connection.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
These instruments effectively resist splaying, ensuring stable attachment to vertebral anchors, enabling precise derotation and fixation procedures while allowing access for other instruments, thus enhancing the reliability and efficiency of spinal deformity correction surgeries.
Implementation Method 1
pivot arms with biasing mechanisms, that prevent splaying
Data Source
Figure 1
Figure 2~2A
Figure 3
AI summary
A surgical instrument (100) for correcting spinal deformities includes a tubular body (110) adapted to receive a second instrument (200) through the tubular body (110). The tubular body (110) forms a transverse passage (126) adapted to receive a longitudinal fixation element through the tubular body (110). The tubular body (110) further includes first and second arms (150, 160) for connecting the surgical instrument (100) to a vertebral anchor (300). The first and second arms (150, 160) include one or more anti-splaying features adapted to mate with anti-splaying features on the second instrument (200) to prevent the first and second arms (150, 160) from splaying as the second instrument (200) is inserted into the tubular body (110).