Citrate-Based Rotator Cuff Patch With Graded Enthesis Regeneration
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Solution Overview
Problem
Current rotator cuff repair methods, such as arthroscopic single or double-row repair, suffer from high re-tear rates due to the formation of reactive scar tissue at the tendon-bone interface, which disrupts the natural enthesis and reduces mechanical strength, and existing scaffolds fail to regenerate the anatomical enthesis layers effectively.
Innovation Solution
A citrate-based polymer-bioceramic patch system with a porosity gradient and aligned fibers is developed to mimic the native enthesis layers, promoting directional growth of tenocytes and osteocytes, and is designed to degrade over 4-12 months, incorporating 3D printing for precise control over fiber size, direction, and spacing to enhance tissue integration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If arthroscopic single or double-row repair is performed, then the torn tendon is reattached to the bone, but the formation of reactive scar tissue occurs at the tendon-bone interface which reduces mechanical strength and increases re-tear rates
Solution Approach 1:
The patent introduces an interpositional patch as a mediator between the tendon and bone. This patch is composed of multiple layers including a fibrocartilaginous layer that mimics the natural enthesis structure. The patch prevents direct contact between tendon and bone, thereby preventing reactive scar tissue formation while maintaining mechanical stability. The intermediate layer serves as a barrier that eliminates the harmful scar tissue response.
Solution Approach 2:
The patent changes the physical and chemical parameters of the tendon-bone interface by introducing a graded structure with varying porosity and composition across different layers. The interpositional patch has a gradient structure where the fibrocartilaginous layer has specific porosity and mechanical properties that differ from both tendon and bone, creating an optimal interface that prevents scar tissue formation while maintaining strength.
2Strength
If traditional scaffolds are used to thicken the tendon, then mechanical stability is improved, but the scaffolds fail to regenerate the anatomical enthesis layers and degrade too quickly
Solution Approach 1:
The patent divides the scaffold into multiple distinct layers, each with specific functions and degradation rates. The interpositional patch includes a fibrocartilaginous layer, a collagen layer, and other specialized layers. Each layer can be optimized for specific mechanical properties and degradation timelines, allowing the overall structure to maintain strength while individual layers degrade at appropriate rates to facilitate tissue regeneration.
Solution Approach 2:
The patent uses composite materials comprising multiple polymers and biomaterials with different degradation rates and mechanical properties. The interpositional patch is made from a combination of materials such as polyglycolic acid, polylactic acid, and collagen, creating a composite structure that balances mechanical stability with controlled degradation. The composite nature allows slower-degrading materials to provide structural support while faster-degrading materials facilitate tissue ingrowth.
3Strength
If a dense structure is used to provide mechanical strength, then the interface strength is improved, but cell infiltration and tissue regeneration are hindered
Solution Approach 1:
The patent applies the principle of local quality by creating regions with different porosity and structural characteristics within the interpositional patch. The fibrocartilaginous layer has specific porosity optimized for cell infiltration, while other layers have denser structures for mechanical strength. This spatial variation in local properties allows simultaneous optimization of both strength and cell infiltration without compromise.
Solution Approach 2:
The patent incorporates porous structures within the interpositional patch, particularly in the fibrocartilaginous layer, to facilitate cell infiltration and tissue regeneration. The controlled porosity allows cells to migrate through the scaffold while the overall structure maintains sufficient mechanical strength. The pore size and distribution are optimized to balance these competing requirements.
Data Source
AI summary
A synthetic rotator cuff repair scaffold/patch system fabricated from citrate-based materials is provided. The biodegradable scaffold/patch system includes (i) a citrate component and/or other carboxylic acid components, (ii) a polyol, and (iii) particulate inorganic material. The patch system includes a patch that defines a patch thickness and may define a porosity gradient across the patch thickness.