Intervertebral Disc Prosthesis With Cylindrical Articulation Surfaces
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current intervertebral disc prostheses face challenges such as migration, stress on facet joints, and limited durability due to inappropriate biomechanical stress, leading to potential arthritis and the need for revision surgery, especially in cases where facet joints show signs of arthritis or malpositioned prostheses, and they often require ventral surgery which poses risks.
Innovation Solution
A two-part intervertebral disc prosthesis with a cylindrical convexity and concavity design that allows dorsoventral motion and rotation, while limiting sideways bending, featuring articulating sliding partners with edges that form an interdigitating articulation area, providing a larger load-bearing surface and reducing strain on facet joints, and can be implanted via a lateral or ventrolateral approach to avoid ventral scarring and facilitate optimal load transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional intervertebral disc prosthesis is implanted via ventral approach, then the prosthesis can be positioned in the intervertebral space, but it causes ventral scarring and poses surgical risks
Solution Approach 1:
The patent inverts the conventional ventral approach by implementing a lateral approach for prosthesis implantation. The prosthesis is inserted through the lateral aspect of the vertebral column rather than through the ventral midline, thereby avoiding ventral scarring and associated surgical risks while maintaining access to the intervertebral space
2Ease of operation
If the prosthesis allows free sideways bending, then mobility is maintained, but it causes malpositioning and stress on facet joints leading to arthritis
Solution Approach 1:
The articulation surfaces are designed with asymmetric curvature characteristics - specifically a cylindrical curvature with the radius extending in the dorsoventral direction rather than laterally. This asymmetric geometry naturally guides motion along the dorsoventral axis while providing geometric constraint against excessive lateral bending, thereby protecting facet joints from abnormal stress
Solution Approach 2:
The patent employs curved cylindrical articulation surfaces with specific radius of curvature in the dorsoventral direction. This curvature design allows smooth dorsoventral motion while the geometric constraints of the curved surfaces prevent malpositioning and limit harmful lateral movements that would stress the facet joints
3Device complexity
If the articulation surfaces have small contact area, then the prosthesis design is simpler, but it leads to inappropriate biomechanical stress and reduced durability
Solution Approach 1:
The articulation surfaces are designed as curved cylindrical surfaces with optimized radius of curvature. This curvature geometry increases the effective contact area between articulating surfaces compared to flat or spherical designs, distributing biomechanical stresses more evenly across the prosthesis and improving durability without significantly increasing design complexity
Data Source
AI summary
An intervertebral disc prosthesis for the total replacement of an intervertebral disc within the lumbar and cervical spine is disclosed. The intervertebral disc prosthesis comprises articulating sliding partners, wherein the upper sliding partner is adapted for a firm assembly to an upper vertebral body and the lower sliding partner is adapted for a firm assembly to a lower vertebral body. The functional two part design provides a dorsoventral motion and in the transversal plane a rotational motion around a fictitious vertical axis as a result of a laterolaterally aimed, transversally arched, ventrally curved cylindrical convexity and corresponding concavity but prevents an inclination of the sliding partners in a lateral direction. According to the invention, the intervertebral disk prostheses are suited for implantation from lateral and ventrolateral, particularly in revision surgeries.