Transverse Connector Locking Cap Bearing Surface Spine Stabilization
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Solution Overview
Problem
Standard trans- connectors are not suitable for spine stabilization systems due to the proximity of polyaxial bone screws, which requires a more appropriate connector to provide rigidity by attaching to the heads or 'tulips' of opposing screws.
Innovation Solution
A spine stabilization system featuring bone anchors with receiving portions for elongated rods, locking caps with threaded portions and flanges, and a top connector with elongated openings that allow medial-lateral translation and locking, providing additional bearing surfaces for enhanced fixation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a standard trans-connector is used to affix directly onto the titanium alloy rods, then the connector can be easily installed, but it is not suitable due to the proximity of the bone screws and cannot provide adequate rigidity
Solution Approach 1:
The connector is divided into multiple components: a top connector body with elongated openings, locking caps with bearing surfaces, and locking nuts. This segmentation allows each component to perform its specific function - the top connector provides the rigid structure, the locking caps provide bearing surfaces for rod attachment, and the locking nuts secure the assembly, collectively achieving the required rigidity while managing complexity through functional specialization
Solution Approach 2:
The connector transitions from a simple direct-attachment design to a multi-dimensional assembly with vertical stacking (top connector, locking caps, locking nuts) and horizontal elongated openings. This dimensional change allows the connector to span across screw trajectories in three dimensions, providing rigidity while accommodating the anatomical constraints of nearby bone screws
2Adaptability or versatility
If the polyaxial bone screws are placed close together due to natural anatomy, then the screw placement follows natural anatomical constraints, but the standard trans-connector cannot be properly installed
Solution Approach 1:
The top connector incorporates elongated openings that allow dynamic adjustment and translation of the locking caps along the rod axis. This dynamic design enables the connector to adapt to varying screw spacings and anatomical configurations while maintaining ease of installation through a flexible assembly process where components can be positioned and secured in sequence
Solution Approach 2:
The locking caps serve as intermediary elements between the top connector and the bone screws. These caps with bearing surfaces mediate the connection by providing attachment points for the rod while allowing the top connector to span across the anatomical constraints created by closely spaced screws, thus facilitating installation in challenging anatomical scenarios
3Reliability
If additional bearing surfaces are added to enhance fixation, then the spinal stabilization is improved, but the device complexity increases
Solution Approach 1:
The locking caps integrate multiple functions into a single component: they provide bearing surfaces for rod attachment, serve as retention elements to capture the rod, and interface with both the top connector and locking nuts. This merging of functions reduces the total number of separate components while enhancing fixation reliability through the integrated bearing surfaces
Solution Approach 2:
The top connector design with elongated openings serves multiple purposes: it provides the rigid structural framework, allows translation and adjustment of the locking caps, accommodates varying screw configurations, and enables secure locking through the nut-caps-connector assembly. This multi-functionality enhances spinal stabilization without requiring additional separate components
Data Source
AI summary
The present invention provides a spine stabilization system having a first bone anchor having a first receiving portion and a second bone anchor having a second receiving portion. The first and second elongated rods are positioned within the first and second receiving portions. The first and second locking caps are configured to retain and capture the first and second elongated rods within the first and second bone anchors. The top connector is configured with a first and a second end, which are provided with elongated openings. The first and second locking caps have a threaded portion for coupling to a first and second locking nut. The locking caps are also provided with at least one flange for coupling to the bone anchor, and a bearing surface spaced apart from the bone anchor, the bearing surface configured to contact the top connector.