Spinal Implant Collet Mechanism for Low-Force Rod Attachment
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Solution Overview
Problem
Current spinal implant systems for treating disorders such as scoliosis and degenerative disc disease face challenges in providing a secure and efficient method for attaching vertebral rods to vertebrae, often requiring high forces for assembly and disassembly, which can complicate surgical procedures and affect stability.
Innovation Solution
A modular spinal implant system featuring a bone fastener with a collet mechanism that allows for easy assembly and disassembly using a screw shaft, where the collet can be rotated 180 degrees to transition between open and closed positions, facilitating a secure snap-fit engagement with minimal force requirements, typically in the range of 2 to 50 Newtons.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional spinal implant systems are used to attach vertebral rods to vertebrae, then secure fixation is achieved, but high forces are required for assembly and disassembly which complicates surgical procedures
Solution Approach 1:
The collet mechanism transitions between static and dynamic states during assembly. Initially in a static closed position to maintain secure fixation, it becomes dynamic when the surgeon activates it to expand and release the rod, allowing easy disassembly without high forces. This dynamic capability resolves the contradiction between secure fixation and ease of operation.
Solution Approach 2:
The collet acts as an intermediary component between the bone fastener and the vertebral rod. It provides a mechanical interface that enables secure attachment during surgery while allowing controlled release when needed. The collet's expandable nature mediates between the need for strong fixation and the need for simple assembly/disassembly operations.
2Stability of the object's composition
If traditional spinal implant systems are used, then stable attachment is achieved, but high assembly forces complicate surgical procedures
Solution Approach 1:
The system transitions from a static high-force attachment mechanism to a dynamic one where the collet can be easily expanded and collapsed. During normal use, the collet maintains stable attachment, but when disassembly is needed, it transitions to a low-force state that simplifies surgical procedures. This dynamic behavior resolves the contradiction between stability and force requirements.
3Ease of operation
If a secure snap-fit engagement is used with minimal force, then ease of assembly is improved, but pull-out strength may be compromised
Solution Approach 1:
The attachment system is segmented into distinct functional components: the collet with its expandable fingers, the rod interface, and the fastening mechanism. This segmentation allows the assembly operation to be simplified (easy expansion/collapse) while maintaining strong pull-out resistance through the distributed finger engagement with the rod. Each segment optimizes for its specific function, resolving the contradiction between ease of operation and strength.
Data Source
AI summary
A method of assembly for a bone fastener is provided. The method includes the steps of: engaging a retainer with an implant receiver in a relatively fixed position; translating the retainer relative to the implant receiver to an expandable orientation; and manually engaging a screw shaft with the retainer to connect the implant receiver with the screw shaft. Implants, systems and instruments are disclosed.