Bone Anchoring Device with Preload Clamping Mechanism
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Solution Overview
Problem
In complex clinical applications, bone anchoring devices with freely pivotable heads relative to the receiving part can complicate alignment and insertion of stabilization rods, especially when multiple anchors are involved, due to the lack of secure temporary clamping mechanisms.
Innovation Solution
A bone anchoring device with a pressure element and receiving part featuring projections and recesses that allow temporary clamping of the head without locking, enabling adjustable angular positioning and facilitating rod alignment and insertion, while allowing for subsequent locking in the desired position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the head of the anchoring element is freely pivotable with respect to the receiving part, then the device allows for angular adjustment and adaptability, but the alignment of the receiving part and insertion of the rod becomes difficult in complex clinical applications
Solution Approach 1:
The pressure element is designed to automatically apply a preload force onto the head when inserted into the receiving part, preliminarily clamping the head in an angular position before the rod is inserted. This preliminary clamping action facilitates subsequent alignment and insertion of the rod without requiring the head to be freely pivotable during these operations.
Solution Approach 2:
The system transitions from a static locked position to a dynamic adjustable position. The pressure element can be inserted at different angular positions and will clamp the head at that position through its preload force. The head can be adjusted by removing the pressure element, and the system can lock in the desired position by pressing the pressure element onto the head. This dynamic behavior allows both adaptability and ease of operation.
2Stability of the object's composition
If a locking mechanism is implemented to fix the head position, then alignment stability is improved, but the ability to adjust the rod position is restricted
Solution Approach 1:
The locking mechanism is designed to be reversible. The pressure element can be pressed onto the head to lock it in the desired position through friction, and can be removed to allow adjustment. This dynamic locking mechanism provides stability when needed while maintaining adaptability when required.
Solution Approach 2:
The pressure element acts as an intermediary between the receiving part and the head. When pressed onto the head, it transmits the locking force through friction to stabilize the head position. When removed, it allows the head to be adjusted. This intermediary component enables both locking and adjustment functions without requiring complex mechanisms.
3Device complexity
If the pressure element is held in place by crimp bores, then the assembly is simplified, but sufficient movement of the pressure element to clamp the head is impeded
Solution Approach 1:
The pressure element is designed with a two-part structure: a body portion that engages with the receiving part and a separate clamping portion that contacts the head. The body portion can be held in place by simple crimp bores or projections, while the clamping portion maintains sufficient movement freedom to apply the necessary preload force onto the head. This segmentation allows both assembly simplicity and operational capability.
Solution Approach 2:
The clamping function is extracted from the positioning function. The pressure element's body portion can be securely held by simple crimp bores for assembly simplicity, while its clamping portion is designed to move freely enough to apply preload force. The extraction of the clamping function allows independent optimization of both positioning security and movement capability.
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 surgical handling by allowing temporary clamping and preload without locking, facilitating rod alignment and insertion, and enabling adjustments without completely loosening the head, while being easy to assemble and disassemble, reducing manufacturing costs and inventory complexity.
Implementation Method 1
the pressure element can assume a position within the receiving part in which it clamps the head by friction without locking it
Data Source
Figure 1~2
Figure 3~8
Figure 9a~9c
AI summary
A bone anchoring device is provided including an anchoring element (2) having a shaft (3) for anchoring in the bone and a head (4), a receiving part having a top end (51) and a bottom end (52), a recess (55) for receiving a rod therein, a coaxial bore (53) extending from the top end (51) in the direction of the bottom end (52) and a seat (54) for receiving the head near the bottom end; a pressure element (6) which is movable within the bore (53); wherein the head (4) is pivotable with respect to the receiving part (5) and can be fixed at an angle by exerting pressure via the pressure element onto the head, and wherein so the pressure element (6) has an outer wall portion with a recess (67a,67b) or a projection and wherein the receiving part (5) has an inner wall portion with a projection (59a, 59b) or a recess which cooperates with said recess (67a,67b) or projection of the pressure element; and wherein the pressure element can assume a first position (P 1 ) in which the recess (67a,67b) and the projection (59a, 59b) cooperate in such a way that the pressure element exerts a preload onto the head in which the head is prevented from freely pivoting but is not locked.