Rod-to-Bone Coupling Assembly With Pre-Locking Retainers
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Solution Overview
Problem
Existing coupling assemblies for coupling a rod to a bone anchoring element are not safely handled during surgery, and there is a need for improved safety and ease of assembly, especially in in-situ applications.
Innovation Solution
A coupling assembly with a receiving part and a pressure element that includes a flexible portion to clamp the bone anchoring element's head, featuring a first retaining member to prevent escape from the top end and a second retaining member to prevent inadvertent removal through the bottom end, allowing safer handling and alignment during surgery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pressure element is used to clamp the bone anchoring element head, then the head can be securely held, but the pressure element may escape from the top end or allow inadvertent removal through the bottom end
Solution Approach 1:
The first retaining member is pre-installed in the receiving part to prevent pressure element escape before assembly, and the second retaining member is designed to automatically engage with the pressure element during assembly, providing preliminary protection against inadvertent removal
Solution Approach 2:
The first retaining member acts as an intermediary between the receiving part and pressure element to prevent escape, while the second retaining member serves as an intermediary between the pressure element and bone anchoring element head to prevent inadvertent removal
2Ease of operation
If the coupling assembly allows free movement of the pressure element for easy assembly, then insertion is simplified, but alignment and handling safety are compromised
Solution Approach 1:
The first retaining member is pre-positioned to guide the pressure element into correct alignment during insertion, and the second retaining member is designed to automatically engage at the proper position, eliminating the need for complex alignment procedures while preventing handling errors
Solution Approach 2:
The retaining members are designed to automatically guide and secure the pressure element and bone anchoring element head during assembly without requiring external alignment tools or complex manual positioning, making the assembly process self-aligning and safe
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
The assembly provides safer handling and easier alignment of bone anchoring devices during surgery, preventing inadvertent removal of the head and facilitating secure attachment of rods to bone anchoring elements.
Implementation Method 1
The pressure element has a flexible portion to clamp a head of the bone anchoring element. The pressure element can assume in the receiving part an insertion position where insertion and removal of the head is permitted, a locking position where the head is locked in the receiving part, and a pre-locking position where the head is pivotable but is prevented from removal from the receiving part.
Data Source
AI summary
A coupling assembly for coupling a rod to a bone anchoring element includes a receiving part with an accommodation space defining an opening for inserting and accommodating a head of the bone anchoring element, and a pressure element having a cap portion configured to hold the head. In an inserting position, the cap portion of the pressure element is expandable in the accommodation space of the receiving part, and a first retaining element is configured to prevent the pressure element from moving towards a first end of the receiving part. In a pre-locking position, the head is held in the cap portion of the pressure element and is pivotable in the receiving part, while the cap portion is restricted from expanding to prevent removal of the head, and where a second retaining element is configured to prevent the pressure element from moving from the pre-locking position towards the inserting position.