Polyaxial Ball and Socket Fastener with Bottom-Loading Spring Clip
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Solution Overview
Problem
Current spinal implant systems face challenges in achieving stable angular placement of polyaxial pedicle screws during installation, requiring large inventories of varying sizes and complicating surgical procedures due to the need for precise bone structure determination and angular adjustments.
Innovation Solution
A bottom-loading polyaxial ball and socket joint system that allows snap-together assembly with a U-shaped connector and split ring retainer mechanism, enabling stable angular positioning and easy attachment of connecting rods, reducing the need for extensive inventory and simplifying surgical procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a polyaxial pedicle screw is inserted into the bone, then the connector component can be positioned at multiple angles, but the connector assembly lacks stabilization and flops over making it difficult to grasp during surgery
Solution Approach 1:
A stabilization member is introduced as an intermediary component between the connector component and the bone screw. This stabilization member extends into the bone screw to provide structural support and prevent the connector assembly from flopping over, while still allowing the connector to be positioned at multiple angles relative to the bone screw during installation.
2Manufacturing precision
If multiple component heads are aligned for receipt of a connecting rod, then proper alignment is achieved, but the complexity of alignment increases
Solution Approach 1:
The stabilization member is designed to automatically align the connector component with the bone screw during insertion. The stabilization member extends into the bone screw and provides self-aligning features that guide the connector into the correct position, eliminating the need for complex manual alignment procedures by the surgeon.
3Measurement precision
If bone structure is determined during surgery, then proper implant selection is possible, but a large inventory of various sized implants is required
Solution Approach 1:
The polyaxial ball and socket fastener system is designed with universal adaptability to accommodate different bone structures and anatomical variations. The stabilization member and connector component can be adjusted to work with various bone sizes and configurations, allowing a single implant system to serve multiple patient anatomies, thereby reducing the need for maintaining large inventories of differently sized implants.
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 placement and easy installation of connecting rods, reducing surgical complexity and inventory requirements, while allowing for adjustable component alignment and secure attachment to the spine.
Implementation Method 1
a spring clip (144) constructed and arranged to engage the bone screw (12)
Implementation Method 2
a split ring retainer mechanism, enabling stable angular positioning
Data Source
AI summary
The bottom loading fastening system that consists of the polyaxial ball and socket joint used in conjunction with a bone screw having threads on one end for use in anchoring to the spine and a spherical connector on the other end operating as a pivot point about which a connecting assembly moves in a polyaxial fashion. A substantially U-shaped connecting assembly has a lower receptacle having at least two retainer rings within at least two retaining ring grooves for use in securing the spherical connector to the connecting assembly.