Bone Anchoring Device Pre-Locking Mechanism
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Solution Overview
Problem
Existing bone anchoring devices are not optimized for small size and safe handling during surgery, with complex designs and potential for inadvertent removal of the bone anchoring element.
Innovation Solution
A bone anchoring device with a pre-locking position for the locking ring, allowing the head of the bone anchoring element to be pivoted but not removed, achieved through engagement with rod supporting projections in a channel, simplifying the design and reducing the overall size of the device.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the locking ring design is simplified by engaging with rod supporting projections, then the overall device size is reduced, but the reliability of preventing inadvertent removal must be maintained
Solution Approach 1:
The locking ring is designed with upwardly extending projections that preliminarily engage with the rod supporting projections in the channel before final locking. This preliminary engagement prevents inadvertent removal of the bone anchoring element while allowing the head to pivot, achieving safety without requiring a complex multi-position locking mechanism.
2Ease of operation
If the locking ring allows head pivoting in pre-locking position, then ease of operation during surgery is improved, but the stability of the bone anchoring element is reduced
Solution Approach 1:
The locking ring is designed to be movable along the bone anchoring element, transitioning between a pre-locking position that allows head pivoting and a locked position that prevents both pivoting and removal. The upwardly extending projections engage with the rod supporting projections to maintain stability during pivoting while allowing positional adjustment of the locking ring itself.
3Device complexity
If the locking ring uses upwardly extending projections engaging with rod supporting projections, then device complexity is reduced, but the precision of locking position control must be maintained
Solution Approach 1:
The rod supporting projections in the channel serve multiple functions: they provide structural support for the rod, engage with the upwardly extending projections of the locking ring to prevent inadvertent removal, and define the locking position through their geometric relationship with the channel walls. This multi-functionality reduces the need for separate precision positioning features.
Data Source
AI summary
A bone anchoring device includes a bone anchoring element including a shaft and a head, a receiving part for coupling a rod to the bone anchoring element, the receiving part including a rod receiving portion having a channel with a bottom for receiving a rod, and a head receiving portion to allow introduction and clamping of the head, and a locking ring including at least one projection, wherein the rod receiving portion has at least one cutout, wherein when the head is not locked, the projection is configured to extend through the cutout and into the channel, and wherein a first engagement portion is provided on the locking ring for engaging a second engagement portion at an inner wall of the cutout to hold the locking ring in a first position where the head is pivotable in the head receiving portion but is prevented from removal therefrom.