Intervertebral Implant Asymmetric Teeth Directional Rotation
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Solution Overview
Problem
Existing intervertebral implants face difficulties in rotation and slipping out due to their structural design, which either facilitates or hinders insertion and rotation in both directions, and lacks effective prevention of reverse rotation and lateral movement.
Innovation Solution
A cuboid-shaped intervertebral implant with inclined macroscopic teeth on its contact surfaces, allowing rotation in one direction while preventing it in the other, and featuring a design that prevents slipping out and reverse rotation, made from X-ray permeable materials with a roughened surface for better bone adhesion and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the contact surfaces have a structure with ribs or teeth, then the implant can be prevented from slipping out, but rotation of the implant becomes difficult in both directions
Solution Approach 1:
The patent applies asymmetry by creating teeth with asymmetric flanks where one flank is steeper than the other. This asymmetric geometry allows the implant to be rotated easily in one direction (where the shallower flank engages) while preventing rotation in the opposite direction (where the steeper flank would resist). The asymmetric tooth structure thus resolves the contradiction by providing directional differentiation in rotational resistance.
Solution Approach 2:
The patent inverts the conventional symmetric tooth design by intentionally creating unequal flanks. Instead of having equal resistance to rotation in both directions, the design creates a scenario where rotation is facilitated in one direction and prevented in the other. This inversion of the typical symmetric approach allows simultaneous achievement of easy insertion/rotation and prevention of reverse rotation or slipping out.
2Device complexity
If symmetric teeth with equal flanks are used, then the implant structure is simple, but both insertion and rotation are equally facilitated or prevented
Solution Approach 1:
The patent introduces asymmetry into the tooth structure by making the flanks unequal in steepness. This modification maintains relative structural simplicity while fundamentally changing the operational characteristics. The asymmetric design allows differential response to rotational forces, enabling easy rotation in one direction while preventing it in the opposite direction, thus resolving the contradiction between structural simplicity and operational ease.
3Difficulty of detecting and measuring
If the implant body is made from X-ray permeable material, then visibility during surgery is improved, but bone adhesion may be reduced
Solution Approach 1:
The patent applies local quality by differentiating the surface properties of the implant. The contact surfaces are specifically roughened to enhance bone adhesion, while the overall material composition remains X-ray permeable for visibility. This localized modification of surface texture without changing the bulk material properties allows simultaneous achievement of radiological visibility and biological integration.
Solution Approach 2:
The patent employs composite material strategies by combining X-ray permeable material with a roughened surface treatment. The roughening process creates a composite structure where the base material provides radiological visibility while the surface layer enhances bone adhesion. This composite approach resolves the contradiction by integrating two seemingly opposing requirements through material and surface treatment combination.
Data Source
AI summary
An implant for an intervertebral space with a shaped body. The implant has a top contact surface to be placed on a base plate of a body of the vertebra adjoining the implant from above, a bottom contact surface to be placed on a cover plate of a body of the vertebra adjoining the implant from below, two lateral surfaces, a front lateral and a rear lateral surface as well as a central axis that intersects the two contact surfaces, a longitudinal axis that intersects the front and rear lateral surfaces and a transverse axis that intersects the lateral surfaces. The implant also has a central plane situated between the contact surfaces and at right angles to the central axis of the body. The contact surfaces have a plurality of macroscopic teeth with central axes, where the central axes of the plurality of teeth are inclined relative to the central plane in such a manner, that a rotation of the body of 90° about the longitudinal axis is facilitated in one direction and impeded in the other direction. The distance between the two lateral surfaces is smaller than the distance between the two contact surfaces.