Articulating Intervertebral Implant Multi-Axis Motion
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Solution Overview
Problem
Conventional spinal disc replacement methods in the cervical region often result in loss of mobility due to removal of ligaments, which are essential for normal anatomical motion, and existing artificial discs do not adequately replicate the natural spine's movement patterns.
Innovation Solution
An intervertebral implant with endplates featuring articulation members that allow rotation about perpendicular axes, enabling flexion, extension, lateral bending, and axial rotation while maintaining stability, thus preserving natural spinal motion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If ligaments are removed during surgical procedures to access the intervertebral space, then surgical accessibility is improved, but natural anatomical motion is lost
Solution Approach 1:
The implant serves as an intermediary structure that replaces the function of removed ligaments. The articulation members with their specific geometries (cam surfaces, recesses, protrusions) act as mechanical mediators that replicate the motion-control function of the anterior and posterior longitudinal ligaments, allowing surgical access while preserving natural motion patterns through the implant-ligament complex replacement strategy
2Device complexity
If conventional artificial discs are used that do not replicate natural movement patterns, then device simplicity is maintained, but motion accuracy deteriorates
Solution Approach 1:
The implant employs dynamic articulation mechanisms where the articulation members can rotate relative to each other about perpendicular axes. The cam surface and recess/protrusion geometry enable the upper and lower articulation members to follow natural cervical spine motion paths during flexion-extension and axial rotation, transforming a simple static implant into a dynamically adaptive device that replicates complex physiological movements
Solution Approach 2:
The patent introduces multi-axis rotation capability by allowing articulation members to rotate about perpendicular axes simultaneously. This dimensional expansion from single-plane motion to multi-planar articulation enables the implant to replicate the complex three-dimensional movement patterns of natural cervical spine, including the coupling between axial rotation and lateral bending that occurs in physiological motion
3Reliability
If articulation members are designed to allow multi-axis rotation, then natural motion replication is improved, but device complexity increases
Solution Approach 1:
The articulation system is segmented into distinct functional components: upper articulation member, lower articulation member, cam surfaces, and recesses with protrusions. Each segment performs a specific function (rotation about one axis, constraint in another direction, guidance of motion path), allowing the complex multi-axis articulation to be achieved through modular, independently designed elements that can be manufactured and assembled separately
Data Source
Figure 1A~1B
Figure 1C~1D
Figure 1E~1F
AI summary
An intervertebral disc implant for use in the spine includes a superior endplate and an inferior endplate. The superior endplate is configured to articulate about the inferior endplate in an anterior-posterior direction during flexion and extension. The superior endplate is further configured to axially rotate about the inferior endplate during axial rotation, and is further configured to articulate about the inferior endplate along a medial-lateral direction during lateral bending. During axial rotation, the superior endplate is induced to articulate about the inferior endplate along the medial-lateral direction. During lateral bending, the superior endplate is induced to axially rotate about the inferior endplate.