Spinal Interbody Device with Serrated One-Way Surfaces
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Solution Overview
Problem
Current interbody devices for spinal and long bone applications face challenges in providing adequate support while minimizing subsidence and promoting bone fusion, as they need to be small and lightweight yet maintain strength and engage a large bone surface area effectively.
Innovation Solution
The development of interbody devices with serrated surfaces for one-way implantation, internal cavities for bony ingrowth, and undercuts to support bone growth, along with various shapes and bores for improved fit and stability, ensures secure placement and integration with the bone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Weight of moving object
If interbody devices are made small and lightweight to be more compatible with the body, then device compatibility and reduced invasiveness are improved, but device strength and ability to support bone surfaces deteriorate
Solution Approach 1:
The interbody device utilizes a composite structure combining a porous outer shell with an inner core material. The porous shell engages with bone tissue while the inner core provides structural strength. This composite approach allows the device to be lightweight yet sufficiently strong to support bone surfaces without subsidence.
Solution Approach 2:
The device incorporates a porous outer shell that allows bone ingrowth while maintaining structural integrity. The porous structure reduces device weight and improves bone compatibility, while the controlled porosity ensures the device maintains sufficient strength to prevent subsidence into the vertebral bodies.
2Weight of moving object
If interbody devices are made small and lightweight, then device compatibility is improved, but the ability to engage large bone surface area deteriorates
Solution Approach 1:
The porous outer shell provides a large surface area for bone engagement and ingrowth. The porous structure increases the effective surface area available for bone contact without significantly increasing device volume or weight, allowing small devices to engage large bone surface areas effectively.
Solution Approach 2:
The device incorporates surface features such as ridges, grooves, and porous structures that add dimensional complexity to the device-bone interface. These features increase the effective engagement area by utilizing surface topology rather than simply increasing device volume, allowing compact devices to achieve large bone surface contact.
3Ease of operation
If smooth surfaces are used for easy implantation, then ease of insertion is improved, but prevention of device removal and backing out deteriorates
Solution Approach 1:
The device incorporates asymmetric features such as directional ridges or one-way engagement structures that allow easy insertion in the forward direction but prevent removal or backward movement. The asymmetric geometry permits smooth insertion while creating mechanical interlocking that prevents device backing out, resolving the contradiction between ease of insertion and retention reliability.
4Weight of moving object
If device volume is reduced to minimize weight, then device compatibility is improved, but ability to promote bone fusion deteriorates
Solution Approach 1:
The porous outer shell provides extensive surface area for bone ingrowth and fusion, compensating for reduced device volume. The porous structure allows bone tissue to penetrate and integrate with the device, promoting fusion even in compact, lightweight devices. The high surface-area-to-volume ratio of the porous structure enables effective bone engagement without increasing device size.
Solution Approach 2:
The device utilizes surface topology and porous structures to increase the effective bone interaction area without increasing device volume. By transitioning from a smooth surface to a three-dimensional porous architecture, the device maintains compact dimensions while providing sufficient surface area for bone fusion.
Data Source
AI summary
Lumbar and cervical interbody or intervertebral devices for implantation between adjacent vertebrae of a spine and/or within intermediary canals of long bones are characterized by a body defining a superior end and an inferior end whose surfaces have serrations or teeth thereon forming anti-backout structures that allow implantation of the body but inhibit removal or backing out therefrom. The one-way structures may extend from the anterior end to the posterior end. The one-way structures may take different shapes but are always configured to allow insertion of the interbody device in an anterior-first manner while preventing and/or inhibiting the interbody device from backing out posteriorly. The various interbody devices may be further characterized by a body defining a cavity that is in communication with the superior and inferior ends of the body and at least one lateral side thereof via openings in the body. Undercuts are formed in the body about the adjacent the openings in order to support bony ingrowth within the void.