Polyaxial Bone Screw Assembly for Spinal Fixation
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Solution Overview
Problem
Existing spinal fixation systems face challenges in accessing the disc space due to the size of polyaxial pedicle screws, which limits surgical options and increases costs due to the need for various screw sizes and configurations to accommodate different anatomical characteristics.
Innovation Solution
A polyaxial bone screw assembly that allows for initial placement of the bone screw in the bony structure before attaching the receiver assembly, enabling polyaxial motion and secure fixation of a rod, with a design that includes a cannulated core for easy placement and a closure structure for securing the rod, facilitating easier access and alignment during spinal surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If polyaxial pedicle screws are used for spinal fixation, then fixation strength is improved, but access to disc space is obstructed due to screw size
Solution Approach 1:
The spinal fixation system is divided into separate components: a bone screw with a head and a receiver assembly. The bone screw can be inserted into the pedicle first, then the receiver assembly is attached to the head, allowing the screw to be placed before disc space preparation without obstructing the surgical corridor.
Solution Approach 2:
The bone screw is inserted into the pedicle before the receiver assembly is attached. This preliminary placement allows the screw to be positioned in the bony structure prior to disc space preparation and implant insertion, eliminating the obstruction problem.
2Adaptability or versatility
If multiple screw sizes and configurations are provided to accommodate different anatomical characteristics, then adaptability is improved, but device complexity and cost increase
Solution Approach 1:
The receiver assembly is designed to be universal and can be attached to different bone screw configurations (cannulated or non-cannulated, various lengths and diameters). This single receiver assembly serves multiple functions and accommodates different anatomical characteristics without requiring multiple specialized screw designs.
Solution Approach 2:
The invention combines the bone screw and receiver assembly into a unified system where the receiver assembly can interface with various screw types. This merging approach allows different screw configurations to be used with a common receiver assembly, reducing overall system complexity.
3Ease of operation
If disc space is prepared and implant positioned before fixation system placement, then surgical access is improved, but procedural steps and complexity increase
Solution Approach 1:
The bone screw is placed in the pedicle before disc space preparation. This preliminary action allows the fixation system to be partially assembled before the disc space is opened, eliminating the need to prepare the disc space first and reducing procedural complexity.
Solution Approach 2:
The system allows dynamic assembly during surgery where the bone screw can be inserted first, then the receiver assembly is attached to the head. This dynamic approach provides surgical flexibility and allows the surgeon to adapt the sequence of operations based on specific anatomical considerations.
Data Source
AI summary
The present invention involves a system and methods for assembling and implanting a polyaxial bone screw assembly. The polyaxial bone screw assembly includes, but is not necessarily limited to, a bone screw that can be initially secured to a bony structure and subsequently have a receiver assembly attached to the implanted bone screw. Additionally, a closure structure is a part of the polyaxial bone screw assembly and functions to secure an elongate member within the receiver assembly.