Cement Mold Assembly for Antibiotic-Loaded Knee Joint Spacers
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Solution Overview
Problem
Current techniques for delivering antibiotics to infected joint areas during orthopedic surgical procedures are cumbersome, difficult to use, and may cause complications due to limited mobility and soft tissue contraction, especially when using antibiotic-loaded bone cement in a doughy state.
Innovation Solution
A cement mold assembly comprising a first and second mold, with the second mold progressively advanced into the first to form a unitary tibial component, allowing for controlled delivery of antibiotics, and optionally incorporating a reinforcement member and articulating forming portions to create a temporary implant.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If antibiotic-loaded bone cement in a doughy state is used to fill the distracted joint area, then the antibiotic can be delivered to the infected site, but the procedure becomes difficult and messy to use during surgery
Solution Approach 1:
The patent prepares antibiotic-loaded bone cement beads beforehand and loads them into a delivery device before surgery. This preliminary preparation eliminates the messiness of mixing doughy cement during surgery, while ensuring reliable antibiotic delivery to the infected site through the controlled release from the pre-loaded beads.
Solution Approach 2:
The patent introduces a delivery device as an intermediary between the antibiotic cement and the infected site. The device contains pre-loaded antibiotic beads and provides a controlled mechanism for delivering them to the distracted joint area, making the procedure easier to operate while maintaining reliable antibiotic delivery.
2Reliability
If the joint is distracted to create voids for antibiotic cement placement, then the antibiotic can be delivered to the infected area, but soft tissue contraction causes smaller bone portions making revision surgery more difficult
Solution Approach 1:
The patent performs the distraction and void creation as a preliminary step before implanting the antibiotic delivery system. By preparing the site in advance and loading the antibiotic beads into a delivery device beforehand, the surgery becomes more organized and less complex, while ensuring reliable antibiotic delivery to the prepared voids.
Solution Approach 2:
The patent segments the antibiotic delivery into discrete pre-loaded beads contained within a delivery device. This segmentation allows for controlled placement into the distracted joint voids without requiring complex manipulation of doughy cement, reducing surgical complexity while maintaining reliable antibiotic delivery.
3Adaptability or versatility
If a temporary implant with stem is formed using progressive mold advancement, then various stem sizes can be accommodated, but the device complexity increases
Solution Approach 1:
The patent uses a nested mold assembly where an inner mold is positioned within an outer mold. The inner mold forms the stem portion while the outer mold forms the main body. This nesting arrangement allows the creation of implants with various stem sizes by adjusting the inner mold configuration, while the nested structure itself provides an organized framework that manages the overall device complexity.
Solution Approach 2:
The patent segments the mold assembly into distinct inner and outer mold components, each responsible for forming specific portions of the implant. The inner mold creates the stem with various sizes, while the outer mold forms the tibial tray. This segmentation allows for adaptability in stem sizing while keeping each mold component relatively simple in design.
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
Enables efficient and controlled delivery of antibiotics to infected sites, reducing surgical complexity and mobility issues, while forming a stable temporary implant for enhanced infection management.
Implementation Method 1
Progressive advancement of the second mold into the tibial component forming cavity urges cement within the tibial component forming cavity against the body portion and the inner wall to form a unitary tibial component
Data Source
AI summary
A cement mold assembly configured to form a temporary implant for use in delivering antibiotics to an infected site can includes a first mold and a second mold. The first mold can have an open end and an inner wall. The first mold can define a tibial component forming cavity including a platform forming cavity and a stem forming cavity. The second mold can have a body portion configured to be slidably and progressively receivable by the inner wall into the tibial component forming cavity in a direction toward the closed end. Progressive advancement of the second mold into the tibial component forming cavity urges cement within the tibial component forming cavity against the body portion and the inner wall to form a unitary tibial component having a tibial tray portion formed by the platform forming cavity and a stem portion formed by the stem forming cavity.