Multi-Planar Taper Lock Screw Torqueless Spinal Fixation
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Solution Overview
Problem
Conventional spinal fixation systems lack the necessary variability and instrumentation for easily locking and unlocking multi-planar taper lock screws, which can cause torsional forces that damage fragile bones and complicate spinal fusion procedures, especially when vertebrae are not aligned on the same plane.
Innovation Solution
A novel spinal fixation system featuring a multi-planar taper lock screw with a slidable outer housing and inner housing configuration, along with complementary locking and unlocking instruments that allow for torqueless locking and unlocking of spinal rods, eliminating the need for additional locking pieces like set screws or nuts.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If conventional set screws or nuts are used for locking the screw and rod, then the locking function is achieved, but torsional forces are transmitted to the bone which can damage fragile bones
Solution Approach 1:
The patent replaces the conventional mechanical locking system (set screws or nuts requiring torque application) with a friction-based locking mechanism. The rod is inserted into the screw head and locked through friction between the rod surface and the inner wall of the screw head, eliminating the need for additional locking pieces that transmit torsional forces to the bone.
Solution Approach 2:
The invention extracts and eliminates the additional locking pieces (set screws or nuts) from the system. The locking function is integrated directly into the screw head structure, where the friction between the rod and screw head inner wall provides the locking mechanism without requiring separate components that would transmit torsional forces.
2Ease of operation
If conventional locking instruments are used, then locking function is provided, but the instruments are generic and inadequate for quickly locking or unlocking multi-planar screws
Solution Approach 1:
The screw head structure is designed to be self-locking through friction between the rod and the inner wall of the screw head. The rod itself serves as the locking element when inserted into the screw head, eliminating the need for complex generic locking instruments. The system locks itself through the friction mechanism.
Solution Approach 2:
The friction-based locking mechanism provides both locking and unlocking functions through the same structural interface. The rod can be inserted to lock and removed to unlock, providing multi-functionality without requiring different instruments for different operations.
3Reliability
If additional locking pieces like set screws or nuts are used, then secure locking is achieved, but the device complexity increases and additional torque application is required
Solution Approach 1:
The patent merges the locking function into the screw head structure itself. The inner wall of the screw head and the rod surface work together as an integrated friction-based locking system, eliminating the need for separate locking pieces and reducing overall device complexity while maintaining locking security.
Data Source
AI summary
Provided is a spinal fixation system including a taper lock screw including an inner housing and an outer housing that are translatable relative to one another to transition the taper lock screw between a locked position and an unlocked position. A locking device releasably connects to and operationally interacts with a flange of the taper lock screw. An unlocking device releasably connects to and operationally interacts with inner housing unlocking tool receptors of the taper lock screw to unlock the taper lock screw.