Spinal Bone Fastener With Elastic Band Assembly
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Solution Overview
Problem
Current spinal implant systems for treating disorders such as kyphosis, scoliosis, and degenerative disc disease often require instrumentation for assembly, which can apply excessive preload on vertebrae and complicate surgical procedures, limiting the range of motion and stability during healing.
Innovation Solution
A bone fastener system with a selectively coupled pedicle screw design that allows for angular movement and assembly without instrumentation, featuring a base with grooves and bands that facilitate expansion and contraction to secure the screw shaft, enabling easy manual assembly and reduced preload on vertebrae, with components that can be assembled on a surgical table or in-situ with minimal force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If instrumentation is used for assembly of spinal implant systems, then assembly precision and stability are improved, but device complexity and surgical procedure complexity increase
Solution Approach 1:
The bone fastener system is designed to be self-assembling through inherent mechanical features: the band automatically engages with the screw shaft when the receiver is positioned, and the projection-recess interface automatically orients components correctly. This eliminates the need for external instrumentation during assembly, reducing surgical complexity while maintaining assembly precision through built-in mechanical guidance.
Solution Approach 2:
The bone fastener is divided into distinct modular components (receiver, screw shaft, band, projection, recess) that can be independently manufactured and assembled. The segmentation allows each component to have optimized features for its specific function, with the projection and recess providing automatic alignment and the band providing secure engagement without requiring complex assembly instrumentation.
2Stability of the object's composition
If instrumentation is used for assembly, then stability during healing is improved, but preload on vertebrae increases
Solution Approach 1:
The band is designed with elastic properties allowing it to dynamically adjust and contract around the screw shaft. This dynamic engagement provides stable fixation while distributing forces more evenly, reducing peak preload on the vertebrae compared to rigid instrumentation-based assembly systems.
Solution Approach 2:
The self-assembling mechanism inherently controls the engagement forces through the mechanical interaction of the projection, recess, and elastic band. This self-regulating system prevents excessive preload application that might occur with manual instrumentation, while still achieving stable fixation for healing.
3Ease of operation
If bands are made expandable, then ease of assembly is improved, but device complexity increases
Solution Approach 1:
The band's physical parameter of elasticity is utilized to enable expandability. By selecting appropriate material properties and geometric dimensions, the band can be expanded during assembly to accommodate the screw shaft and then contract to provide secure engagement. This parameter-based approach achieves ease of assembly without requiring complex mechanical expansion mechanisms.
Solution Approach 2:
The band is designed as a flexible elastic component that can be expanded and contracted. This flexible shell approach simplifies the assembly process by allowing the band to be positioned and then secured through elastic contraction, avoiding the need for complex fastening mechanisms while maintaining structural integrity.
4Adaptability or versatility
If angular movement is allowed, then adaptability to different spinal configurations is improved, but fixation stability may be compromised
Solution Approach 1:
The system provides dynamic adaptability through the angular slot and projection mechanism, allowing the receiver to be positioned at different angles relative to the screw shaft. Once positioned, the elastic band contracts to provide stable fixation, creating a system that is both adaptable during assembly and stable during healing.
Solution Approach 2:
The angular adjustment capability is achieved through segmented design elements: the slot provides the angular range, the projection defines the orientation, and the band secures the position. This segmentation allows independent optimization of each function (adjustment, positioning, fixation) without compromising overall stability.
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 stable angular adjustment and secure fixation of spinal rods with reduced preload on vertebrae, allowing for effective treatment of spinal disorders with minimal surgical complexity and reduced risk of tissue damage, while enabling easy assembly and high pull-out strength.
Implementation Method 1
the second band is expandable between a provisional capture orientation and an expanded orientation
Implementation Method 2
the third band is expandable between a contracted orientation and an interference orientation to fix connection of the base and the second member
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A bone fastener comprises a first member defining an implant cavity and a first groove. A first band is disposable in the first groove. A base is connectable with the first member and engageable with the first band. The base defines a second groove and a slot. A second band is disposable in the second groove and defines an opening aligned with the slot. A second member is connectable with the base and engageable with the second band. The second member is configured to penetrate tissue. The opening is aligned with the slot to facilitate an angular range of movement of the second member relative to the first member. Implants, spinal constructs, systems, instruments and methods are disclosed.