Polyaxial Ball Socket Fastener Preloaded Ring Set
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Solution Overview
Problem
Current spinal fixation systems require a large inventory of variously sized implants due to the variability in bone strength and position, making it difficult for surgeons to find the appropriate anchoring devices during surgery, and existing polyaxial pedicle screws lack a reliable mechanism for secure attachment without vertical displacement.
Innovation Solution
A bottom-loading polyaxial ball and socket joint fixation system using a preloaded ring set consisting of a blocker ring and a split ring, where the blocker ring is counter-bored to receive the split ring, allowing only horizontal expansion and preventing vertical movement, ensuring a secure and snap-together assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a large inventory of various sized implants is maintained to accommodate bone variability, then the surgeon can find appropriate anchoring devices, but the device complexity and inventory management burden increase
Solution Approach 1:
The connector assembly is designed with a universal interface that can accommodate multiple anchor sizes through the same polyaxial insertion mechanism. The counter-bored blocker ring and split ring system provides a standardized connection interface that works with various anchor dimensions, eliminating the need for different connector types for different bone conditions.
Solution Approach 2:
The system separates the anchoring function (bone insertion) from the connection function (rod attachment). The polyaxial base with spherical ball connector allows the anchoring portion to be optimized for bone engagement while the connector assembly provides standardized connection, enabling modular inventory management where connectors are universal but anchors can be size-specific.
2Ease of operation
If traditional split ring attachment is used without vertical displacement constraint, then assembly is simple, but the reliability of attachment is compromised
Solution Approach 1:
The split ring is pre-loaded onto the spherical ball connector before final assembly, ensuring proper positioning and orientation. The counter-bored blocker ring is pre-configured with the split ring in place, so that when the anchor is inserted, the connection is immediately established with correct geometry, preventing misalignment or improper seating that would compromise reliability.
Solution Approach 2:
The counter-bored blocker ring serves as an intermediary component between the split ring and the final connection structure. It provides a controlled interface that guides the split ring into proper position while preventing vertical displacement, thereby ensuring reliable attachment without requiring complex assembly procedures.
3Adaptability or versatility
If the split ring is allowed vertical movement during assembly, then the assembly process is flexible, but permanent attachment and secure locking cannot be achieved
Solution Approach 1:
The design constrains the split ring movement from three-dimensional freedom to primarily horizontal expansion within the counter-bored blocker ring. By restricting vertical movement through the blocker ring's geometry, the system transforms the assembly process into a controlled two-dimensional expansion action, ensuring precise final positioning while maintaining assembly simplicity.
Solution Approach 2:
The split ring's elastic properties enable it to self-constrain within the counter-bored blocker ring during assembly. As the anchor is inserted and the split ring expands, it naturally seats itself against the blocker ring's counter-bore surface, which prevents vertical displacement. This self-constraining mechanism eliminates the need for additional locking steps or complex tooling.
Data Source
AI summary
A bottom loading fastening system that consists of the polyaxial ball and socket joint used in conjunction with an anchoring bone screw. The system allows attachment of a connector assembly to the anchoring bone screw having a spherical ball connector using a blocker ring preloaded with a split ring. Upon installation, the blocker ring and split ring are expanded into an expansion slot, causing relocation of said split ring into a lower groove, permanently attaching said connector assembly to said anchoring bone screw. The blocker ring having a counter-bored inner surface allowing said split ring to be preloaded to facilitate manufacturing. Dislodgement of the split ring from the blocker ring produces an audible and tactile indication that the sufficient force has been applied to lock the connector assembly to the bone screw.