Microstructured Implant Surfaces for Spinal Fusion
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Solution Overview
Problem
Conventional spinal implants with random and irregular surface patterns face challenges in achieving consistent and efficient bone integration, leading to instability and potential complications due to variable bone growth patterns and directional loading issues.
Innovation Solution
A spinal implant with a defined, repeating three-dimensional surface pattern featuring overlapping two-dimensional patterns of varying depths, designed to promote bone growth and integration by creating a uniform bioactive micromorphology that enhances stability and long-term function.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If random and irregular surface patterns are used on implants, then manufacturing is simpler and easier, but bone integration consistency and reliability deteriorate
Solution Approach 1:
The patent transforms the surface pattern from random/irregular to controlled parameters including specific feature sizes (10-100 micrometers), defined geometries (dimples, grooves, ridges), and regulated spacing (5-50 micrometers). This parameter control enables repeatable manufacturing while ensuring consistent bone integration and osseointegration across all implants.
Solution Approach 2:
The surface is segmented into multiple distinct feature types (dimples, grooves, ridges, peaks) with specific functions. Each feature type addresses different aspects of bone interaction: dimples for initial attachment, grooves for bone in-growth channels, and ridges for mechanical interlocking. This segmentation allows systematic optimization of each feature while maintaining overall manufacturing feasibility.
2Reliability
If deep surface features are created to enhance bone in-growth, then bone integration improves, but stresses between bone and implant increase
Solution Approach 1:
The patent optimizes feature depth parameters to balance bone integration with stress reduction. Feature depths are controlled at 5-50 micrometers, with overall surface roughness Ra of 1-10 micrometers. This controlled depth range provides sufficient bone in-growth while avoiding excessive stress concentration that would occur with deeper features.
Solution Approach 2:
Different surface features are assigned different depths and geometries based on their local function. Dimples have moderate depths for initial attachment, grooves have varying depths to guide bone in-growth, and ridges have optimized heights for mechanical support. This local quality differentiation allows each feature to perform its function optimally without creating excessive stress.
3Reliability
If irregular surface patterns are used to accommodate organic bone growth, then initial bone adherence is achieved, but long-term stability and load resistance deteriorate
Solution Approach 1:
The surface is segmented into multiple feature types that work together sequentially: dimples (10-50 micrometers) provide initial bone adherence through increased surface area and micro-shielding effects; grooves (5-20 micrometers wide) guide organized bone in-growth; and ridges provide long-term mechanical interlocking and load distribution. This segmented approach addresses both initial adherence and long-term strength requirements.
Solution Approach 2:
The patent transitions from two-dimensional random patterns to three-dimensional structured features with controlled depths, volumes, and spatial relationships. The features extend 5-50 micrometers into the implant surface, creating a volumetric interaction zone that enhances both initial adherence through surface area increase and long-term strength through mechanical interlocking of bone with the three-dimensional feature structure.
Data Source
Figure 1A~1B
Figure 2~3B
Figure 4A~4D
AI summary
An implantable device for treating disc degenerative disease and arthritis of the spine. The implant is sized for placement into an intravertebral disc space. The implant has a body with a predetermined, defined, repeating, three-dimensional pattern at least partially on at least one of its surfaces. The pattern is adapted to create a surface area of bone-contacting features that enhance in-growth and biological attachment to a biocompatible material. Also disclosed are process steps for making the implant.