Polyaxial Cross Connector with Hook and Ferrule for Spinal Rod Angulation
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Solution Overview
Problem
Existing spinal cross connector systems are limited in allowing angulation of spinal support rods and often require additional components and bone excision, with set screws causing damage to the rods due to direct contact.
Innovation Solution
A polyaxial cross connector system with elongated members featuring hooks and ferrules that allow up to 20 degrees of perpendicular engagement, minimizing rod damage through a secure attachment mechanism without direct set screw contact, enabling a wide range of angulation and reducing the need for additional connectors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If prior cross connector systems use perpendicular connector rods attached to spinal support rods, then the connection structure is simple, but the system requires additional mid-spine connector pieces and bone excision when rods are non-parallel
Solution Approach 1:
The connector is divided into distinct functional segments: a body portion with a polyaxial rod receptacle for receiving and angulating the first rod, and an elongated connector rod extending from the body for connecting to the second rod. This segmentation allows independent optimization of each component's function, enabling wide angulation capability while maintaining a relatively simple overall structure.
Solution Approach 2:
The connector is designed to perform multiple functions: it connects two spinal support rods, allows for polyaxial angulation of the first rod relative to the second rod, and provides a secure locking mechanism. By integrating these functions into a single component rather than requiring separate pieces, the connector reduces device complexity while maintaining adaptability to various rod orientations.
2Reliability
If set screws are used to secure the cross connector to spinal support rods, then the attachment is secure, but the direct contact causes plastic deformation and damage to the rod
Solution Approach 1:
A rod receptacle or receiving structure is introduced as an intermediary between the set screw and the spinal support rod. The set screw secures the connector to the rod by engaging with this receptacle rather than making direct contact with the rod itself. This intermediary protects the rod from plastic deformation and damage while maintaining secure attachment through the receptacle-secured connection.
3Adaptability or versatility
If polyaxial screws allow wide angulation of spinal rods, then the alignment flexibility is improved, but the rods may diverge in two or three planes making connection difficult
Solution Approach 1:
The connector design incorporates a polyaxial rod receptacle that accepts rods at multiple angles in three-dimensional space. The receptacle is configured to receive a first rod at an angle relative to a second rod, allowing connection even when rods diverge in multiple planes. This dimensional flexibility in the receptacle design enables easy connection while maintaining the alignment flexibility provided by polyaxial screws.
Data Source
AI summary
A connector device for a spinal stabilization apparatus comprises a first elongated member having first and second ends, and is adapted to engage a first spinal stabilizer rod proximal to the first end of the elongated member and is further adapted to engage a spinal cross connector rod proximal to a second end of the first elongated member. The first end of the first elongated member comprises a hook shape and a ferrule and may engage the first spinal stabilizer rod within about 20 degrees of perpendicular to the spinal stabilizer rod in any direction. The ferrule is adapted to be seated within the hook shape and is further adapted to engage the first spinal stabilizer rod. A second elongated member substantially similar to the first may additionally be used in a spinal stabilization apparatus. The connector device may be used in a method of treating a patient.