Sacrum Anchor Assembly with Polyaxial Link for Vertebral Fixation
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Solution Overview
Problem
Existing vertebral osteosynthesis equipment often fails to provide strong anchoring to the sacrum, especially when the bone quality is poor, and can lead to undesirable stress on the fifth and fourth lumbar vertebrae.
Innovation Solution
The equipment includes a sacrum anchor assembly with two screws implanted in different vertebrae of the sacrum, a link assembly allowing polyaxial tilting and pivoting, and a sacral anchor plate connected to these screws, which distributes force evenly and prevents stress on the lumbar vertebrae by allowing the connecting bar to be rigidly affixed without initial clamping, enabling strong anchoring regardless of bone quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional anchoring equipment is used to anchor to the sacrum, then anchoring is achieved, but the anchoring strength is insufficient especially when bone quality is poor
Solution Approach 1:
The sacral anchor assembly is divided into multiple independent components: a first sacral anchor screw, a second sacral anchor screw, a link assembly, and a sacral anchor plate. This segmentation allows each component to be optimized for its specific function while collectively providing strong and reliable anchoring to the sacrum, overcoming the limitations of conventional single-unit anchoring systems.
Solution Approach 2:
The link assembly introduces polyaxiality, allowing multi-directional tilting and pivoting movements between the first and second sacral anchor screws. This adds a dimensional degree of freedom that enables the system to adapt to varying bone qualities and anatomical conditions, thereby improving both anchoring strength and reliability.
2Strength
If conventional sacral anchoring equipment is used, then anchoring to the sacrum is achieved, but undesirable major stress is applied to the fifth and fourth lumbar vertebrae
Solution Approach 1:
The link assembly is designed with dynamic capabilities, allowing polyaxial tilting and pivoting movements. This dynamic design enables the system to absorb and distribute mechanical stresses through controlled movements, preventing the transmission of undesirable major stresses to the fifth and fourth lumbar vertebrae while maintaining strong sacral anchoring.
Solution Approach 2:
The link assembly acts as an intermediary element between the first and second sacral anchor screws and the connecting bar. It mediates the force transmission, allowing the system to achieve strong anchoring to the sacrum while preventing harmful stresses from being imposed on the lumbar vertebrae through its polyaxial tilting and pivoting capabilities.
3Stability of the object's composition
If rigid connection is used to anchor the connecting bar to the sacrum, then stability is achieved, but the system cannot accommodate varying bone conditions
Solution Approach 1:
The link assembly incorporates dynamic elements that allow polyaxial tilting and pivoting movements, enabling the system to adapt to varying bone conditions while maintaining stability. The spherical bearing surfaces and corresponding recesses provide controlled mobility that accommodates different bone qualities and anatomical variations.
Solution Approach 2:
The system allows changes in geometric parameters through polyaxial tilting and pivoting movements at the link assembly. This enables adaptation to varying bone conditions by adjusting the spatial relationships between components, while the rigid connection between the sacral anchor plate and connecting bar maintains overall stability.
Data Source
AI summary
This equipment comprises at least one connecting bar and at least one sacrum anchor assembly (1-3, 5). According to the invention, each sacrum anchor assembly comprises two sacral anchor screws (1, 2), a link assembly (3) including: a sacral connecting part (10) assembled to a sacral anchor plate (11) with polyaxiality, i.e. having possible multi-directional tilting relative to the said first screw (1), and possible pivot relative to the said sacral anchor plate (11); two nuts (5) able to be screwed onto the said shanks (9) of the said first and second screws (1, 2), a first nut (5) is able to clamp this part (10) against a bearing surface (8) formed in the said first screw (1), for tilt and pivot immobilisation of this part (10) relative to the said sacral anchor plate (11).