PEEK Intervertebral Implant Surfaces for Bone Fusion and X-Ray Visibility
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Solution Overview
Problem
Existing interbody fusion devices (IBDs) made of polyetheretherketone (PEEK) have limited bone growth due to smooth surfaces, while titanium-coated PEEK devices obstruct x-ray visibility post-surgery.
Innovation Solution
A PEEK spinal implant with rough, nanostructured surfaces and nubs fabricated via selective laser sintering, combined with machined attachment features for improved bone integration and x-ray transparency, and a design that avoids through apertures for enhanced strength and inserter tool engagement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If PEEK implants have smooth surfaces, then the implant is radiolucent and does not obstruct x-ray viewing, but bone growth onto the implant is minimal
Solution Approach 1:
The patent applies different surface qualities to different regions of the implant. The outer surface remains smooth for radiolucency, while the inner surface that contacts bone is textured to promote osteointegration. This local differentiation allows the implant to simultaneously achieve x-ray transparency and effective bone growth.
2Reliability
If titanium coating is applied to PEEK implant, then bone growth is encouraged, but the implant becomes radio-opaque and obstructs x-ray viewing
Solution Approach 1:
The patent extracts the bone-promoting surface texture from the titanium coating concept and applies it directly to the PEEK material through machining or additive manufacturing. This removes the need for titanium coating entirely, maintaining radiolucency while achieving the desired osteointegration properties.
3Reliability
If continuous ridges are used in throughbore, then bone growth material is retained, but the implant structure becomes more complex
Solution Approach 1:
The patent employs a porous or textured inner surface structure that naturally retains bone growth material through capillary action and mechanical interlocking. This porous approach achieves effective material retention without requiring complex continuous ridge structures, simplifying the overall implant design.
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 implant achieves significant bone fusion and maintains x-ray visibility by promoting bone growth on rough surfaces and distributing inserter tool forces evenly, while avoiding brittleness and obstruction issues.
Implementation Method 1
the body is made from PEEK and is fabricated using selective laser sintering. Fabricating the body by selective laser sintering PEEK produces rough surfaces of the body including surfaces of the nubs
Implementation Method 2
the rough surfaces of the body may have nanostructures that resemble peaks and valleys between the peaks, with an average peak-to-valley distance of approximately 125-129 nanometers and an average peak-to-peak distance of approximately 265-282 nanometers. It has been discovered that the combination of the increased surface area of the nubs and the roughness of the surfaces of the nubs encourages significant bone fusion interaction
Implementation Method 3
because the body is made from PEEK, the body is radiolucent to x-rays and permits a surgeon to view the surgical site post-surgery without obstruction by the implant body
Data Source
AI summary
In accordance with one aspect, a spinal implant for fusing vertebral bones is provided that includes a monolithic body for being inserted between bones. The body has a through opening of the body for receiving bone growth material and a wall of the body extending about the through opening. The wall includes nubs extending into the through opening that increase the surface area of the wall available for bone on-growth.