Pedicle Fastener Assembly Using Cross-Nail Fixation Against Loosening
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Solution Overview
Problem
Existing spinal fixation methods require a large number of screws, are time-consuming, and can lead to screw loosening, especially in poor bone quality, contributing to surgeon fatigue and potential negative outcomes.
Innovation Solution
A pedicle fixation system using impactable fasteners with textured surfaces and secondary fastening mechanisms, such as nails, to secure spinal correction rods with less physical effort, featuring a first nail driven anteriorly and a second nail oriented caudally to enhance stability and prevent loosening.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional pedicle screws are used for spinal fixation, then the spinal column can be stabilized, but the procedure becomes time-consuming and physically demanding for the surgeon
Solution Approach 1:
The fixation system is divided into separate components: impactable fasteners (nails) that are driven into the vertebrae separately from the rod placement. This segmentation allows the surgeon to first secure the fasteners quickly, then manipulate the spine and place the rod without needing to have all screws in place beforehand, thereby reducing overall procedure time while maintaining stabilization reliability
Solution Approach 2:
The patent replaces traditional screw-threaded fixation mechanisms with impactable fasteners (nails) that are driven into the bone using impact force. This substitution eliminates the need for time-consuming screw threading operations and allows for faster fixation while maintaining adequate spinal stabilization
2Reliability
If multiple fixation devices are screwed into the spine before rod placement, then secure fixation is achieved, but surgeon fatigue increases
Solution Approach 1:
The fixation process is segmented into two distinct phases: first, the impactable fasteners are driven into the vertebrae using simple impact forces; second, the rod is placed and secured to these pre-installed fasteners. This segmentation eliminates the need for the surgeon to perform complex screw threading operations while maintaining fixation security, thereby reducing physical effort and fatigue
Solution Approach 2:
The patent replaces the complex screw-threaded mechanical system with a simpler impact-driven nail system. The fasteners are driven into the bone using impact force rather than requiring the surgeon to manually or mechanically thread screws, significantly reducing the physical effort required while maintaining adequate fixation security
3Reliability
If conventional spinal screws are used, then fixation can be achieved, but the screws may turn within the bone causing loosening over time
Solution Approach 1:
The patent replaces conventional screw-threaded fixation with impactable fasteners that are driven into the bone using impact force. This substitution creates a different mechanism of bone engagement that reduces the tendency for the fastener to turn or loosen over time, thereby improving long-term retention duration while maintaining fixation stability
Solution Approach 2:
The patent changes the key parameter of how the fastener engages with the bone - from threaded engagement (screws) to impact-driven engagement (nails). This parameter change in the fixation mechanism reduces the risk of turning and loosening, improving the duration that the fastener remains securely retained in the bone
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
Facilitates faster and more efficient spinal fixation with improved resistance to drifting and loosening, reducing surgeon fatigue and enhancing the stability of the spinal correction rod.
Implementation Method 1
Either or both of the first fastener and the second fastener may include rings or a texture along their respective shanks to promote retention in bone
Implementation Method 2
Either or both of the first fastener and second fastener may be an impactable fastener, such as a nail
Data Source
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AI summary
A pedicle fixation system (10) may include a first fastener (12) and a second fastener (14). The first fastener (12) may include a first shank (40) extending along a first fastener axis (41) and a channel (52) extending along a skew axis (51). The skew axis (51) may be transverse to the first fastener axis (41) and the channel (52) may have a channel diameter perpendicular to the skew axis (51). The second fastener (14) may extend through the channel (52) and include a second shank (60) extending along a second fastener axis (63). At least a distal part of the second shank (60) may have a second fastener diameter perpendicular to the second fastener axis (63). The second fastener diameter may be smaller than the channel diameter.