Polyaxial Rod Coupling Assembly With Spring-Locked Head Retention
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing polyaxial bone anchoring devices face challenges in ease of handling during surgery and lack modularity, limiting their versatility and application variety.
Innovation Solution
A coupling assembly with a pressure element featuring circumferentially extending spring portions that engage the inner wall of a receiving part, allowing for improved assembly and preventing upward movement of the bone anchoring element, combined with modular rod receiving elements and interchangeable closure mechanisms, enabling a variety of applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a pressure element with circumferentially extending spring portions is used to engage the inner wall of the receiving part, then the assembly ease is improved and upward movement is prevented, but the device complexity increases
Solution Approach 1:
The pressure element is divided into multiple circumferentially extending spring portions that can independently engage with the inner wall of the receiving part. This segmentation allows the pressure element to flexibly adapt to the receiving part geometry while maintaining secure engagement, improving assembly ease without requiring a completely complex structure.
Solution Approach 2:
The spring portions are designed to nest within the receiving part structure, with the pressure element fitting into the accommodation space and engaging with the inner wall. This nested configuration allows the pressure element to provide retention functionality while minimizing additional space requirements and reducing overall device complexity.
2Adaptability or versatility
If modular rod receiving elements with interchangeable closure mechanisms are provided, then the adaptability is improved for different applications, but the device complexity increases
Solution Approach 1:
The rod receiving elements are designed as modular components that can be used with different closure mechanisms, creating a universal system that handles multiple rod diameters and surgical applications. This multi-functionality approach allows a single rod receiving element design to serve various purposes by simply changing the closure mechanism, improving adaptability without proportionally increasing complexity.
Solution Approach 2:
The modular design allows the system to dynamically adapt to different surgical requirements by interchangeably selecting rod receiving elements and closure mechanisms based on the specific application needs, such as rod diameter or surgical approach, providing versatility while maintaining manageable complexity through standardized interfaces.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Facilitates easier assembly and handling of polyaxial bone anchoring devices, supports rods of different diameters, and reduces costs by providing modularity, allowing for a wide range of surgical applications.
Implementation Method 1
The pressure element comprises at least one spring portion that is extending over a length in a circumferential direction and that is configured to engage a portion of an inner wall of the receiving part so that the pressure element is held in a position
Implementation Method 2
the spring portion is compressible in a radial direction... In a first engagement position, the spring portion engages a first engagement structure... In a second engagement position, the spring portion engages a second engagement structure
Implementation Method 3
In the pre-locking position of the pressure element, the head of the bone anchoring element may be held by a frictional force exerted by the pressure element onto the head. The frictional force may be such that pivoting of the head is still possible by applying a force to overcome the frictional force.
Data Source
AI summary
A coupling assembly is provided comprising a receiving part (6) having a first end (6a), a second end (6b) and a central axis (C) extending through the first end and second end,a recess (62) for receiving a rod (100,101), andan accommodation space (61a,61b) for accommodating a head (3) of an anchoring element (1), the accommodation space having an opening (72) at the second end (6b) for inserting the head (3),a pressure element (7,7′) configured to be positioned at least partly in the accommodation space, the pressure element having a first end (7a) and a second end (7b), wherein the second end (7b) is configured to be positioned closer towards the second end (6b) of the receiving part than the first end (7a), and a flexible portion (74,75,76,77) to clamp an inserted head (3);wherein the flexible portion (74,75,76,77) comprises a hollow interior chamber (71) for accommodating a head of a bone anchoring element therein;a rod receiving element (8,8′) that is a separate part comprising a groove (81) for supporting an inserted rod (100,101);characterized in that the pressure element (7,7′) further comprises at least one spring portion (79a,79b), the spring portion extending over a length in circumferential direction around the central axis (C) and being compressible in a radial direction; wherein the spring portion (79a, 79b) is configured to engage an engagement structure (65,66,67) at an inner wall of the receiving part (6) to be prevent movement of the pressure element towards the first end of the receiving part.