Intervertebral Implant Truss Density and Strut Orientation
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Solution Overview
Problem
Intervertebral implants face challenges in consistently facilitating the flow of bone graft material and providing structural support across different types of bone, such as cortical and cancellous bone, leading to varying bone ingrowth results.
Innovation Solution
The design of an intervertebral implant with a central portion of reduced truss density to facilitate bone graft material flow and a peripheral portion with higher truss density for structural support, along with struts of non-circular cross-sectional shapes to direct and promote the flow of bone graft material, addresses these issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the implant has consistent structural configuration across bone contacting surfaces, then manufacturing is simplified, but bone ingrowth results vary between cortical and cancellous bone areas
Solution Approach 1:
The implant features different truss densities in different regions: a first truss density in the central portion and a second truss density in the peripheral portion. This local differentiation allows the central region to accommodate viscous bone graft material while the peripheral region provides structural support for cortical bone, resolving the contradiction between manufacturing simplicity and bone ingrowth consistency.
2Strength
If the implant has high truss density throughout, then structural support is improved, but bone graft material flow into the inner volume is hindered
Solution Approach 1:
The implant implements spatially varying truss density with a first density in the central portion and a second density in the peripheral portion. The central region has lower density to facilitate bone graft material flow and introduction, while the peripheral region maintains higher density for structural support, thus resolving the contradiction between strength and ease of operation.
Solution Approach 2:
The implant structure is segmented into distinct regions with different truss densities - the central portion and peripheral portion are differentiated to perform different functions. This segmentation allows the central area to serve as a flow channel for bone graft material while the peripheral area provides structural integrity.
3Ease of operation
If the implant has low truss density in central portion, then bone graft material flow is facilitated, but structural support is reduced
Solution Approach 1:
The implant compensates for reduced central truss density by implementing higher truss density in the peripheral portion. This local quality differentiation ensures that the central region facilitates bone graft material flow while the peripheral region maintains overall structural support, resolving the contradiction between ease of operation and strength.
Data Source
AI summary
An intervertebral implant comprising a body formed as an open truss structure, the body having a generally annular shape with a superior surface, an inferior surface, and a perimeter surface extending around an outer periphery of the body. The body may have a central portion and a peripheral portion, the peripheral portion extending inward from the perimeter surface toward the central portion, the peripheral portion including a first set of trusses, and the central portion including a second set of trusses. The implant may further include a strut at least partially defining a boundary between the central portion and the peripheral portion, wherein the strut has an oblong cross-sectional shape oriented to facilitate flow of bone graft material in a substantially radial direction away from the central axis.