Implantable Bone Device with Controlled Antibiotic Release
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Solution Overview
Problem
Current treatments for periprosthetic infections in total joint replacement surgeries face challenges due to inadequate antibiotic delivery, with traditional systemic antibiotics failing to reach infection sites effectively and biomaterial-based approaches lacking controlled release mechanisms, leading to early burst release and subsequent sub-therapeutic levels, which promotes antibiotic resistance and requires invasive and costly clinical interventions.
Innovation Solution
An implantable device comprising a uniform mixture of degradable polymer, bone, a drug, a microporagen, and a macroporagen, designed to provide controlled antibiotic release and promote osseointegration, using a composite structure that includes polycaprolactone and poly(lactic-co-glycolic acid) polymers with tobramycin, calcium chloride, and ProOsteon synthetic bone, allowing extended antimicrobial activity beyond six weeks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If traditional systemic antibiotics are used, then treatment coverage is broad, but antibiotic delivery to infection sites is insufficient
Solution Approach 1:
The patent uses a biodegradable polymer matrix as an intermediary carrier to transport and release antibiotics directly at the infection site. The polymer acts as a mediator between the antibiotic drug and the infected bone tissue, enabling controlled local delivery that overcomes the limitations of systemic administration.
Solution Approach 2:
The patent changes the physical and chemical parameters of antibiotic delivery by transitioning from systemic circulation to localized controlled release. The biodegradable polymer matrix controls the release kinetics, maintaining antibiotic concentration within the therapeutic window (above MIC) for extended periods, thereby improving infection elimination effectiveness.
2Quantity of substance
If biomaterial-based antibiotic delivery is used, then local delivery is achieved, but controlled release mechanisms are lacking
Solution Approach 1:
The biodegradable polymer matrix enables continuous antibiotic release over an extended period (weeks to months) as the polymer gradually degrades. This continuous release action maintains therapeutic antibiotic levels throughout the infection treatment period, eliminating the need for repeated interventions.
Solution Approach 2:
The patent utilizes the time-dependent degradation of the biodegradable polymer to control the release parameters. As the polymer degrades through hydrolysis of ester bonds, the release rate evolves over time, providing sustained delivery that maintains antibiotic concentration above the minimum inhibitory concentration for the required duration.
3Quantity of substance
If uncontrolled drug release occurs, then initial antibiotic concentration is high, but subsequent levels become sub-therapeutic
Solution Approach 1:
The biodegradable polymer matrix controls the release parameters by adjusting the polymer composition, molecular weight, and degradation rate. This control prevents the harmful burst release effect while ensuring sufficient initial concentration, maintaining the release profile within the therapeutic window throughout the treatment period.
Solution Approach 2:
The patent incorporates a porous structure in the polymer matrix that modulates drug release kinetics. The porous architecture provides channels for controlled diffusion while maintaining sufficient surface area for degradation, enabling sustained release without initial burst effect.
4Reliability
If extended antibiotic release is implemented, then reinfection rates decrease, but antibiotic resistance may develop
Solution Approach 1:
The patent carefully controls the release parameters to maintain antibiotic concentration strictly above the minimum inhibitory concentration (MIC) without excessive surplus. This precise control eliminates sub-therapeutic fluctuations that promote resistance while ensuring continuous effective levels for infection prevention.
Solution Approach 2:
The biodegradable polymer provides a self-regulating feedback mechanism where the release rate is coupled to the degradation progress. As the polymer degrades, the release rate automatically adjusts, ensuring sustained therapeutic levels without creating conditions that would select for resistant bacterial strains.
5Reliability
If bone void filler is used, then bone regeneration is promoted, but antibiotic delivery control is insufficient
Solution Approach 1:
The patent merges the bone void filler function with the controlled antibiotic release function into a single integrated device. The biodegradable polymer matrix simultaneously serves as the structural scaffold for bone regeneration and the controlled release vehicle for antibiotics, eliminating the need for separate components.
Solution Approach 2:
The patent creates a composite material system combining biodegradable polymer, bone void filler particles, and antibiotic drug. This composite structure provides both the mechanical scaffold needed for osseointegration and the controlled release capability for extended antibiotic delivery throughout the bone healing process.
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 device achieves sustained antibiotic release at bactericidal levels for extended periods, reducing reinfection rates and supporting bone regeneration, thereby improving revision TJR procedure outcomes and reducing the economic burden of treating periprosthetic infections.
Implementation Method 1
the degradable polymer has a structure and molecular weight selected so as to degrade over a time period when implanted into a patient and thereby release the drug over the time period
Implementation Method 2
an implantable device comprising a uniform mixture of dispersed components including degradable polymer, bone, a drug, a microporagen and a macroporagen
Data Source
AI summary
In one aspect, the invention provides an implantable device comprising a uniform mixture of components including degradable polymer, inorganic bone particulate either natural or synthetic, a drug, and a soluble microporagen. In some embodiments, the uniform mixture further includes a soluble polymer macroporagen. In some embodiments, the uniform mixture is coated with an immobilized outer porous layer comprising or consisting of synthetic or natural inorganic bone granules. In further aspects, the invention provides an implantable device comprising a composite core of degradable polymer, bone, and a drug, and a coating comprising or consisting of microporous bone overlayer covering the degradable composite core.