Bioresorbable Interference Screw with Hydroxyapatite Coating
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Solution Overview
Problem
Current therapies for bone regeneration face challenges in delivering therapeutic molecules efficiently and effectively, particularly in musculoskeletal conditions, due to issues with targeted and controlled drug delivery, compatibility with standard surgical procedures, and rapid degradation of carrier materials.
Innovation Solution
A bioresorbable interference screw with a hydroxyapatite coating that incorporates biopharmaceutical growth factors, such as BMP-2, for controlled release, providing a targeted and sustained delivery of growth factors during orthopedic surgeries like cruciate ligament reconstruction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional drug delivery methods are used for bone regeneration, then surgical procedures are simpler, but drug delivery is not targeted or controlled
Solution Approach 1:
The patent combines the interference screw (mechanical fixation device) with a hydroxyapatite coating containing growth factors (drug delivery system) into a single integrated component. This merging allows the screw to simultaneously perform mechanical fixation and controlled drug delivery functions, achieving targeted delivery without requiring separate delivery devices.
Solution Approach 2:
The hydroxyapatite coating serves as an intermediary carrier that bridges the mechanical screw and the biological growth factors. It provides a controlled release mechanism for BMP-2 and other growth factors, enabling targeted delivery to the bone regeneration site while the screw provides mechanical stability.
2Duration of action of moving object
If growth factors are delivered rapidly, then initial bone formation is stimulated, but delivery duration is insufficient for sustained regeneration
Solution Approach 1:
The hydroxyapatite coating is designed to release growth factors in a periodic or sustained manner over an extended period (weeks to months). This controlled periodic release maintains adequate growth factor concentrations throughout the bone regeneration process, ensuring both initial stimulation and sustained regeneration.
Solution Approach 2:
The patent utilizes the solubility and degradation parameters of hydroxyapatite to control the release kinetics of growth factors. By adjusting the coating composition and thickness, the release rate is optimized to provide both initial rapid delivery for bone formation stimulation and prolonged delivery for sustained regeneration.
3Reliability
If bioresorbable materials are used as carriers, then biocompatibility is improved, but material degrades too rapidly
Solution Approach 1:
The patent creates a composite structure combining bioresorbable polymer (for biocompatibility and eventual degradation) with hydroxyapatite coating (for enhanced durability and controlled drug release). This composite approach allows the carrier to maintain structural integrity and deliver growth factors over the required time period while remaining biocompatible and eventually resorbable.
Solution Approach 2:
The degradation rate of the bioresorbable material is adjusted through parameter changes in material composition and cross-linking to match the required delivery duration. The hydroxyapatite coating provides a protective layer that modulates the degradation rate, ensuring the carrier remains stable during the drug delivery period and then degrades appropriately.
4Reliability
If high concentrations of growth factors are delivered, then bone regeneration is enhanced, but side effects and costs increase
Solution Approach 1:
The interference screw with hydroxyapatite coating delivers growth factors directly to the local bone defect site where they are needed. This localized delivery concentrates the growth factor effect at the target location, achieving enhanced bone regeneration with lower overall dosages compared to systemic administration, thereby reducing side effects and costs.
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 solution enables effective bone regeneration by ensuring controlled and prolonged release of growth factors, improving graft-bone healing, reducing tunnel widening, and facilitating faster recovery in orthopedic procedures.
Implementation Method 1
controlled release of biopharmaceutical growth factors from hydroxyapatite coating
Implementation Method 2
the coating is adapted to provide targeted and controlled release of the one or more therapeutic growth factors by way of mineral dissolution of the mineral layer
Implementation Method 3
by way of mineral dissolution of the mineral layer
Data Source
AI summary
Controlled release of biopharmaceutical growth factors from a hydroxyapatite coating on a bioresorbable interference screw used in cruciate ligament reconstruction surgery on a human. Biologically active scaffolds, such as interference bone screws used for ligament fixation, made by growing calcium phosphate-based hydroxyapatite coatings on bioresorbable poly(α-hydroxy ester) scaffolds that provide controlled mineral dissolution and controlled release of bone morphogenetic protein-2. The biologically active scaffold provides improved bioavailability of BMP-2 growth factor that in turn provides enhanced graft-bone healing in the tibial bone tunnel. The coating method uses surface hydrolysis and modified simulated body fluid incubation which does not require solvent or heat and is conducted at room temperature.