Wide Angulation Bone Anchor Coupling via Rotatable Yoke
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Solution Overview
Problem
Conventional bone fixation devices face challenges in providing multi-directional and multi-axial stability while maintaining structural integrity, as increasing the angle or size of the opening in the yoke housing compromises the holding strength and increases the risk of accidental separation of the yoke and anchor member.
Innovation Solution
A coupling assembly with a two-part yoke device that allows the anchor member to pivot to extreme angles in limited directions by incorporating a turret-like mechanism, where the upper and lower yoke members are rotatable relative to each other, enabling the anchor member to be fixed at desired angles without requiring significant clearance around the point of exit, thus maintaining strength and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the opening angle and size in the yoke housing are increased to accommodate wider anchor positioning angles, then the adaptability for different anatomical configurations is improved, but the holding strength of the yoke is reduced due to material removal
Solution Approach 1:
The yoke housing is divided into a fixed portion and a movable portion that can rotate relative to each other. The opening is provided in the fixed portion while the movable portion can be positioned at different angles (e.g., 45°, 90°, 135°) to accommodate various anchor positioning requirements. This segmentation allows the opening to remain small and strong in the fixed portion while the movable portion provides the necessary angular adaptability through rotation.
2Ease of operation
If a large circular opening is provided to permit extreme pivotal movement of the anchor in any direction, then the ease of operation for multi-directional positioning is improved, but the structural integrity and reliability of the yoke device is compromised
Solution Approach 1:
The yoke device transitions from a static opening configuration to a dynamic system where the movable portion can rotate to different angular positions. This allows the opening to be small in any given position while still providing multi-directional access through rotation, maintaining both structural integrity and operational flexibility.
Solution Approach 2:
Instead of providing clearance in all directions (360 degrees) around the opening, the invention adds a rotational dimension to the yoke structure. The movable portion rotates about the anchor member axis, effectively providing multi-directional access without requiring a large circular opening, thus maintaining yoke strength while achieving the desired pivotability.
Data Source
AI summary
A coupling assembly is provided with a yoke device that allows an anchor member secured thereto to rotate in a turret-like manner with respect to an elongate member secured by the yoke in addition to allowing the anchor member to pivot away from the central axis of the yoke. A first yoke member holds the elongate member and is rotatably coupled to a second yoke member that holds a bone anchor. A combination of rotation of the second yoke member and pivoting of the anchor member allows the anchor to be positioned in a wide variety of orientations with respect to the yoke device and elongate member.