Rotating Saddle Orthopedic Fixation Assembly Alignment
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Solution Overview
Problem
Current bone fixation devices for spine surgery lack improved functionality, strength, and ease of manufacturing, particularly in securing spinal rods to bone fasteners effectively.
Innovation Solution
The development of an orthopedic fixation assembly that includes a tulip head, a bone fastener, and a locking cap, featuring a saddle that rotates to align with a rod slot, and a threaded locking cap that secures the rod, with indicators for precise alignment and a design that prevents off-angle insertion and disengagement, along with optional features like split rings or clips for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a traditional bone fixation device is used, then the spinal rod can be secured to the bone fastener, but the device lacks improved functionality and strength
Solution Approach 1:
The fixation device is divided into separate functional components: a tulip head for rod reception, a saddle for positioning and alignment, and a locking cap for securing. This segmentation allows each component to be optimized for its specific function, improving overall strength and reliability
Solution Approach 2:
The saddle is positioned within the tulip head, and the locking cap is positioned within the saddle, creating a nested arrangement. This nested structure maximizes space utilization and ensures precise alignment between components, enhancing both strength and functionality
2Ease of manufacture
If a traditional bone fixation device is used, then the spinal rod can be secured to the bone fastener, but the device is difficult to manufacture
Solution Approach 1:
By dividing the device into modular components (tulip head, saddle, locking cap), each can be manufactured separately using standard processes and then assembled. This reduces manufacturing complexity compared to producing a single monolithic structure
Solution Approach 2:
The tulip head serves multiple functions: receiving the spinal rod, providing a threaded interface for the locking cap, and containing the saddle. This multi-functionality reduces the total number of components needed, simplifying manufacturing
3Measurement precision
If a traditional bone fixation device is used, then the spinal rod can be secured to the bone fastener, but the device lacks precision in alignment
Solution Approach 1:
The saddle is pre-configured with a rod seat that is offset from the rod slot, and the groove is pre-formed to guide the saddle into the correct position. This preliminary arrangement ensures precise alignment is achieved automatically during assembly, making the device easy to use
Solution Approach 2:
The groove acts as an intermediary feature between the saddle and tulip head, guiding the saddle into precise alignment with the rod slot. This intermediary element ensures accurate positioning without requiring complex alignment procedures
Data Source
AI summary
Orthopedic fixation devices, assemblies, and methods for securing a spinal rod. The orthopedic fixation device may include a tulip head, a bone fastener, a rotatable saddle, and a threaded locking cap. The saddle may be insertable into the tulip head in an unlocked position with a rod seat offset relative to a rod slot of the tulip head. The saddle may be rotated into a locked position with the rod seat aligned with the rod slot such that a rod is positionable through the rod slot and into the rod seat. The threaded locking cap may secure the rod and bone fastener.