Artificial Disc Segmented Core Rolling Elements
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Solution Overview
Problem
Current artificial discs for replacing injured intervertebral discs do not enable a full range of motion along all degrees of freedom, may not restrict motion properly, and are often incompatible with non-anterior surgical procedures, leading to potential hyperextension and increased stress on surrounding vertebrae.
Innovation Solution
An artificial disc with a four-part design, including a superior endplate, superior core, flexible inferior core, and inferior endplate, made from materials like titanium, Cr-Co-Mo alloy, or PEEK, with serrated keels and plasma spray coatings for bony integration, allowing three to six degrees of movement and compatibility with non-anterior surgical approaches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spinal fusion is performed to treat injured intervertebral disc, then stability and pain relief are improved, but range of motion is lost and stress on surrounding vertebrae increases
Solution Approach 1:
The artificial disc is divided into multiple functional components: superior endplate, inferior endplate, and a core structure with rolling elements. This segmentation allows each component to perform specific functions - the endplates provide stability and bone integration, while the core with rolling elements enables multi-directional movement, thus maintaining both stability and range of motion simultaneously
Solution Approach 2:
The artificial disc incorporates dynamic elements including rolling elements (balls or cylinders) within the core that enable continuous motion between vertebrae. The design allows three to six degrees of freedom through mechanical rolling and sliding actions, transforming the static fusion approach into a dynamic system that mimics natural disc movement while providing stability
2Ease of operation
If current artificial disc design is used, then some range of motion is restored, but full degrees of freedom are not achieved and hyperextension risk remains
Solution Approach 1:
The artificial disc design changes key motion parameters by incorporating rolling elements of specific diameters and positioning them at strategic locations within the core. The radius of the rolling elements is specifically designed to be between 0.1 to 0.5 inches, creating mechanical constraints that naturally limit hyperextension while allowing flexion, extension, lateral bending, and axial rotation within physiological ranges
Solution Approach 2:
The design incorporates geometric features and rolling element positioning that preemptively prevent hyperextension before it occurs. The mechanical structure creates inherent resistance to excessive motion through the arrangement of rolling elements and the curvature of mating surfaces, providing preliminary anti-action against harmful movements while permitting necessary physiological motion
3Ease of manufacture
If traditional disc replacement is performed, then anterior approach is used, but compatibility with non-anterior surgical procedures is limited
Solution Approach 1:
The artificial disc design incorporates universal features including self-aligning geometry and multiple attachment points that enable the device to be successfully implanted through various surgical approaches (anterior, posterior, lateral, or transforaminal). The endplates are designed with features that facilitate bone integration regardless of implantation direction, making the device versatile for different patient anatomies and surgical preferences
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The artificial disc provides a natural range of movement, reduces the risk of hyperextension, and allows for anatomical fit and bony integration, thereby minimizing stress on surrounding vertebrae and facilitating recovery.
Implementation Method 1
with serrated keels and plasma spray coatings for bony integration
Data Source
AI summary
A four-component artificial intervertebral disc may provide six degrees of movement: flexion, extension, lateral bending, axial rotation, axial deflection, and anterior/posterior translation. The disc may include a superior endplate, a superior core, an inferior core, and an inferior endplate. The superior endplate may include a concave mating surface, and the inferior endplate may include a spherical mating surface. The superior endplate may roll across the superior core to provide flexion, extension, and lateral bending. The superior endplate may twist or rotate atop the superior core to provide axial rotation, and the superior endplate may slide over the superior core to provide anterior/posterior translation. The superior core may be connected to the inferior core, and the inferior core may be connected to the inferior endplate. The inferior core may be made from a flexible material that may enable the artificial disc to expand or compress vertically.