Polyaxial Spinal Screw Assembly for Low-Profile Rod Fixation
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Solution Overview
Problem
Existing polyaxial spinal screws lack a unified fixation system for various sizes, are not low profile, and are not designed for minimally invasive fusions, with complex head assemblies that complicate effective fastening and stabilization of spinal rods.
Innovation Solution
A polyaxial spinal screw design featuring a screw shaft with a spherical segment-shaped head, a coupling with a collet mechanism, a sleeve, and a set screw with a collar for secure rod fixation, ensuring ease of use and stability, while allowing angular adjustment and minimally invasive procedures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a complex head assembly design is used, then the fixation system can accommodate various sizes and provide angular adjustment, but the device complexity increases and ease of operation decreases
Solution Approach 1:
The head assembly is segmented into distinct functional components: a receiver member with an axial passage for rod reception, a spherical head on the shank for polyaxial articulation, and a separate locking mechanism. This segmentation allows each component to be optimized independently while maintaining overall versatility and reducing operational complexity.
2Reliability
If a traditional fixation system is used, then spinal stabilization is achieved, but the profile is not low and minimally invasive procedures are not supported
Solution Approach 1:
The design employs a nested structure where the rod-receiving passage is integrated within the receiver member, which itself is part of the spherical head assembly. The locking mechanism is contained within this nested arrangement, creating a compact low-profile configuration that maintains reliable spinal stabilization while enabling minimally invasive procedures.
3Adaptability or versatility
If multiple separate components are used for rod fixation, then adaptability is improved, but the ease of manufacture and assembly decreases
Solution Approach 1:
The receiver member, spherical head, and locking mechanism are merged into an integrated assembly that provides multiple fixation options through a single unified component structure. This merging maintains adaptability for various rod configurations while significantly improving ease of manufacture and assembly compared to using multiple separate components.
Data Source
AI summary
Invention relates to polyaxial spinal screws for correcting and stabilizing a spinal cord by open and minimally invasive technique. The polyaxial spinal screw comprises a screw shaft (10), a coupling (20), a sleeve (30) and a set screw (50). The coupling (20) has a proximal end (202) and a distal end (203). The coupling (20) comprises a spherical cut (21) sized to receive the screw shaft (10). The coupling (20) further comprises two slots (26) for receiving a stabilizing rod (40). The coupling (20) comprises an inner thread (24) where the set screw (50) is threaded. The sleeve (30) has a proximal end (302) closer to the proximal end (202) of the coupling (20) and a distal end (303). The sleeve (30) comprises at least two slots (32) for receiving a stabilizing rod (40) and at least two recesses (33) for fixation of the polyaxial spinal screw by auxiliary tools.