Bone Screw Retaining System with Pinned Elastic Member
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Solution Overview
Problem
Current cervical spine plating systems face challenges in providing secure bone screw retention and removal, often requiring additional locking steps and limiting angular freedom, which complicates implantation and can lead to complications such as screw loosening or backout, and insufficient adaptation to individual anatomy.
Innovation Solution
A bone screw retention system with transversely extending bores and elastically deformable retention members that can be positioned to securely retain screws, and a bone screw removal device with a tongue member and notch mechanism to facilitate easy screw removal, allowing for angular displacement and adaptation to the patient's anatomy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional locking steps are used to secure the screw to the plate, then screw retention reliability is improved, but device complexity and ease of operation deteriorate
Solution Approach 1:
The retention mechanism is segmented into multiple functional elements: a retention member with resilient arms that engage with the screw head, a pin that secures the retention member to the plate, and a cavity that positions these components. This segmentation allows each element to perform its specific function while collectively providing reliable screw retention without requiring complex multi-step locking procedures.
Solution Approach 2:
The resilient arms of the retention member automatically engage with the screw head through elastic deformation when the screw is inserted, providing self-locking functionality. The spring-loaded mechanism self-adjusts to accommodate variations in screw head geometry, eliminating the need for additional manual locking steps while maintaining reliable retention.
2Reliability
If additional locking steps are used to secure the screw to the plate, then screw retention reliability is improved, but ease of operation deteriorates
Solution Approach 1:
The retention member is pre-assembled with the pin and positioned within the cavity during plate manufacturing. This preliminary assembly ensures that when the screw is inserted during surgery, the retention mechanism is already in place and ready to engage automatically, eliminating the need for additional locking steps during the surgical procedure and improving ease of operation.
Solution Approach 2:
The resilient arms automatically engage with the screw head through elastic deformation when the screw is inserted, providing self-locking functionality. The spring-loaded mechanism self-adjusts to accommodate variations in screw head geometry, eliminating the need for additional manual locking steps while maintaining reliable retention.
3Adaptability or versatility
If the plate thickness is reduced to lower prominence, then adaptability to anatomy is improved, but screw retention reliability deteriorates
Solution Approach 1:
The retention mechanism is concentrated in a localized region within the plate thickness, allowing the majority of the plate to remain thin for anatomical adaptation. The cavity, pin, and resilient arms are positioned at specific locations where local structural reinforcement is needed, while the rest of the plate maintains minimal thickness to reduce prominence and improve adaptability to the cervical spine anatomy.
Solution Approach 2:
The plate is constructed using composite materials or multi-layer structures that provide localized reinforcement at the retention mechanism location while maintaining overall thinness. This allows the plate to be thin enough for anatomical adaptation but sufficiently strong at critical points to ensure screw retention reliability.
4Reliability
If the retention member is made rigid to ensure secure screw retention, then screw retention reliability is improved, but adaptability to individual anatomy deteriorates
Solution Approach 1:
The retention member incorporates resilient arms that can dynamically deform elastically to accommodate variations in screw head position and orientation. This dynamic capability allows the retention mechanism to adapt to individual anatomical variations while maintaining secure engagement with the screw head, resolving the contradiction between rigidity for retention and flexibility for adaptation.
Solution Approach 2:
The resilient arms can change their physical state through elastic deformation, transitioning between engaged and disengaged positions. This parameter change allows the retention member to adapt to different screw head geometries and angular orientations while maintaining reliable retention, providing both security and anatomical adaptability.
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
The system provides secure screw retention and easy removal, reducing the risk of screw loosening and backout, while allowing for optimal screw placement and angular adjustment to fit individual anatomy, enhancing surgical precision and patient outcomes.
Implementation Method 1
elastically deformable retention members that can be positioned to securely retain screws
Data Source
AI summary
A bone screw retention system is provided for a plate which defines a plurality of transversely extending bores that are configured to receive a bone screw for engaging the plate to the cervical spine. The retention member has a body and two legs extending therefrom the body. The legs are moveable from a first position to a second position, thereby enabling or preventing movement of a bone screw therein the bores.