Composite Spinal Interbody Device with Non-Aligned Apertures
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Solution Overview
Problem
Conventional spinal implants made of radio-opaque titanium can interfere with diagnostic assessments and delay bone fusion due to their visibility issues in x-rays and MRI/CT scans, and radiolucent polymer implants provide poorer fixation, often requiring additional fixation methods.
Innovation Solution
A composite interbody device comprising radiolucent biocompatible polymer and metallic plates with non-aligned arrays of apertures to facilitate bone growth and secure the device within the intervertebral space, allowing for effective bone fusion while being radiolucent for better diagnostic visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If titanium implants are used, then fixation strength is improved, but diagnostic visualization is worsened due to radio-opacity
Solution Approach 1:
The implant is divided into two distinct components: a radiolucent polymer body for diagnostic visibility and metallic end plates for fixation strength. This segmentation allows each component to fulfill its specific function without compromising the other.
Solution Approach 2:
The implant combines two different materials with complementary properties: radiolucent polymer (PEEK or UHMWPE) for the central body that allows diagnostic imaging, and metallic end plates (titanium or stainless steel) that provide strong fixation to vertebral bodies. This composite structure resolves the contradiction between visibility and strength.
2Difficulty of detecting and measuring
If radiolucent polymer implants are used, then diagnostic visualization is improved, but fixation strength is worsened
Solution Approach 1:
The implant is divided into two distinct components: a radiolucent polymer body for diagnostic visibility and metallic end plates for fixation strength. This segmentation allows each component to fulfill its specific function without compromising the other.
Solution Approach 2:
The implant combines two different materials with complementary properties: radiolucent polymer (PEEK or UHMWPE) for the central body that allows diagnostic imaging, and metallic end plates (titanium or stainless steel) that provide strong fixation to vertebral bodies. This composite structure resolves the contradiction between visibility and strength.
3Reliability
If bone through-growth is encouraged, then fusion is improved, but time required is worsened taking more than a year
Solution Approach 1:
The metallic end plates incorporate porous structures with apertures that facilitate bone ingrowth and through-growth. This porous architecture provides a scaffold for bone cells to migrate and proliferate, accelerating the fusion process while maintaining structural integrity.
Solution Approach 2:
The apertures are strategically positioned in the end plates to create localized zones that promote bone growth. The non-aligned array of apertures in successive plates creates optimal pathways for bone ingrowth without compromising the overall structural strength of the implant.
Data Source
AI summary
A composite interbody device for use with spinal fusion surgery is described herein. The composite interbody device comprises a central body made from a radiolucent biocompatible polymer (e.g., PEEK or UHMWPE) and metallic plates, which are placed at the superior and inferior surfaces of the central body. The metallic plates are comprised of an end plate that is adjacent to a vertebral body and an intermediate plate that is adjacent to the central body. The end plates may have one or more arrays of apertures to facilitate bone growth into the end plates to secure the interbody device within the intervertebral space. The intermediate plates may also have one or more arrays of apertures to allow the central body to bond to the end plates through compression molding, injection molding, and/or heat molding. The arrays of apertures in the end plates are not aligned with the arrays of apertures in the intermediate plates so that polymer material of the central body will not penetrate into the end plate, where bone growth is encouraged, and vice versa.