Bone Anchoring Coupling Assembly Sequential Locking Mechanism
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Solution Overview
Problem
Existing bone anchoring devices face challenges in ease of handling during surgery and limited application due to complex locking mechanisms and compatibility with rods of varying diameters.
Innovation Solution
A coupling assembly that allows sequential locking of a bone anchoring element's head and rod using a single drive, featuring a pressure element with a slit ring for reduced insertion force and a modular design with interchangeable rod receiving elements for different diameters, enabling 360° pivoting and simplified assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex locking mechanism is used to secure the rod and bone anchoring element, then the reliability of the fixation is improved, but the ease of operation during surgery deteriorates
Solution Approach 1:
The locking mechanism is segmented into distinct functional components: a pressure element for clamping the bone anchoring element head, a rod receiving element for holding the rod, and a single drive locking element that sequentially actuates both. This segmentation allows each component to perform its specific function while being controlled through a unified interface, improving both reliability and ease of operation.
Solution Approach 2:
The pressure element is pre-configured with a recess that guides the bone anchoring element head into the correct position before locking. The rod receiving element is pre-positioned to receive the rod, and the single drive locking element is designed to first clamp the head and then secure the rod in sequence. This preliminary arrangement of components ensures reliable fixation while simplifying the surgical procedure.
2Ease of operation
If a single drive locking element is used to simplify the locking process, then the ease of operation is improved, but the device complexity increases due to the need for sequential locking mechanisms
Solution Approach 1:
The functions of clamping the bone anchoring element head and securing the rod are merged into a single locking operation using one drive locking element. The locking element simultaneously engages with both the pressure element and the rod receiving element, allowing sequential locking of both components through a single rotational motion. This merging eliminates the need for multiple separate locking operations while managing the complexity through integrated design.
Solution Approach 2:
The locking mechanism incorporates dynamic elements that allow the single drive locking element to sequentially engage different components during rotation. The pressure element and rod receiving element are designed with dynamic interaction zones that enable the locking element to first clamp the head and then secure the rod in a controlled sequence, transforming a potentially complex multi-step process into a single dynamic operation.
3Reliability
If the pressure element is made rigid to ensure stable clamping, then the reliability of clamping is improved, but the insertion force required increases
Solution Approach 1:
The pressure element's structural parameters are optimized to achieve the right balance between rigidity and flexibility. The element is designed with specific wall thicknesses and geometric features that provide sufficient rigidity for stable clamping while maintaining enough flexibility to be inserted with reduced force. The recess geometry and material properties are carefully selected to transform the insertion process while ensuring reliable clamping performance.
4Manufacturing precision
If the coupling assembly is designed for specific rod diameters to ensure precise fit, then the manufacturing precision is improved, but the adaptability to different rod sizes deteriorates
Solution Approach 1:
The rod receiving element is designed with universal features that allow it to accommodate rods of different diameters while maintaining precise fit. The element includes adjustable or compliant components that can adapt to various rod sizes, and the locking mechanism is configured to work effectively across a range of diameters. This universal design enables a single coupling assembly to serve multiple applications without sacrificing manufacturing precision.
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
Enhances surgical handling and expands application by allowing easy alignment and secure fixation of rods of various diameters, reducing stock-keeping costs and providing a versatile modular system for bone anchoring devices.
Implementation Method 1
The frictional force may be such that pivoting of the head relative to the coupling assembly is still possible by applying a force to overcome the frictional force.
Data Source
AI summary
A coupling assembly for coupling a rod to a bone anchoring element includes a receiving part having a recess for receiving the rod and an accommodation space with an opening for inserting and accommodating a head of the bone anchoring element, a pressure element having a first end surface and a flexible portion to clamp the head, and a rod receiving element configured to be assembled to the pressure element, the rod receiving element having a first end and a second end defining an opening, and a channel for receiving the rod. The channel has a bottom near the second end of the rod receiving element, and the opening of the rod receiving element opens into the channel. The first end surface of the pressure element can extend through the opening of the rod receiving element and past the bottom of the channel to contact the rod.