Polyaxial Bone Anchoring Rod Coupling with Rotating Friction Clamping
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Solution Overview
Problem
Existing coupling devices for coupling a rod to a bone anchoring element are cumbersome and lack efficient mechanisms for adjusting friction force during surgery, particularly for polyaxial bone anchoring elements of the bottom loading type, complicating the alignment of multiple receiving parts.
Innovation Solution
A coupling device with a receiving part, pressure element, and clamping element that allows for stepless adjustment of friction force through a bayonet-like locking advancement structure or threaded connection, facilitating easy assembly and secure fixation of the bone anchoring element.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If existing coupling devices are used for polyaxial bone anchoring elements, then the bone anchoring element can be coupled to the rod, but the device becomes cumbersome and the friction force adjustment is complicated
Solution Approach 1:
The pressure element is designed to be movable along the longitudinal axis of the receiving part body, transitioning between insertion position, pre-locking position, and locking position. This dynamic movement allows the pressure element to exert varying pre-stress on the head, enabling friction-based angular positioning before final locking, thereby simplifying the operation of adjusting friction force.
Solution Approach 2:
The coupling device is divided into distinct functional components: the receiving part body for accommodating the head, the movable pressure element for clamping, and the locking element for final securing. This segmentation allows each component to perform its specific function independently, reducing overall device complexity while improving ease of operation during surgery.
2Reliability
If multiple receiving parts need to be aligned during surgery, then secure fixation is achieved, but the alignment process becomes time-consuming and complex
Solution Approach 1:
The pressure element is pre-configured to exert pre-stress on the head at the pre-locking position, which maintains a desired angular position through friction before final locking. This preliminary friction-based positioning allows surgeons to quickly align multiple receiving parts without requiring precise pre-adjustment, significantly reducing alignment time while maintaining fixation security.
3Reliability
If the head needs to be securely locked in the receiving part, then stable fixation is achieved, but the locking mechanism becomes more complex
Solution Approach 1:
The pressure element is designed to automatically exert pre-stress on the head when moved to the pre-locking position, creating friction that maintains the desired angular position without requiring additional locking components. This self-service friction-based positioning simplifies the locking mechanism while ensuring stable fixation before the final locking element is engaged.
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 device simplifies the handling of bone anchoring devices during surgery by enabling easy adjustment and secure fixation of the bone anchoring element, reducing the complexity of aligning multiple receiving parts and enhancing surgical efficiency.
Implementation Method 1
The pressure element is configured to exert pressure onto a head received therein to clamp and lock the head in the receiving part by friction
Implementation Method 2
a clamping element configured to exert a compression force onto the pressure element to increase a friction force between the pressure element and the head
Data Source
AI summary
A coupling device is provided for coupling a rod to a bone anchoring element. The coupling device includes a receiving part having a first end, a second end, a central axis extending through the first end and the second end, and a channel for receiving a rod. The receiving part defines an accommodation space for accommodating a head of a bone anchoring element, the accommodation space having an opening for inserting the head. The coupling device further includes a pressure element arranged at least partially in the accommodation space, the pressure element having a flexible portion to clamp an inserted head, and a clamping element extending at least partially around the flexible portion of the pressure element. The clamping element is configured to move from a first position to a second position in which the clamping element exerts a clamping force onto the pressure element, where the movement includes rotating the clamping element around the central axis.