Bone Cement Applicator with Retractable Mixing Rod
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Solution Overview
Problem
Existing bone cement applicators require external vacuum pumps and separate extrusion devices for mixing and applying polymethylmethacrylate (PMMA) bone cement, leading to potential leakage, additional steps, and incomplete mixing, which complicates the surgical process and may affect the quality of the bone cement.
Innovation Solution
A closed prepack mixing system with an integrated extrusion device that stores and mixes PMMA bone cement powder and monomer liquid within a cartridge, using a mixing rod with a mixer to combine the components without external vacuum, allowing for direct manual extrusion of the bone cement without additional devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If external vacuum pumps and separate extrusion devices are used for mixing and applying bone cement, then the mixing process can be performed, but the device complexity increases and the risk of leakage occurs
Solution Approach 1:
The patent combines the vacuum mixing system and extrusion device into a single integrated applicator unit. The mixing chamber, vacuum pump, and extrusion mechanism are merged into one device that can perform both mixing and application functions, eliminating the need for separate external devices and reducing leakage risk through integrated sealing.
Solution Approach 2:
The applicator device performs multiple functions within a single unit: it stores bone cement powder, generates vacuum for mixing, mixes the cement components, and extrudes the mixed cement. This multi-functional design eliminates the need for multiple separate devices and reduces overall system complexity.
2Manufacturing precision
If manual mixing with spatulas is used, then the process is simple, but air bubbles are enclosed in the bone cement dough affecting mechanical properties
Solution Approach 1:
The patent uses a vacuum pump integrated into the applicator to create negative pressure during the mixing process. This pneumatic action draws air bubbles out of the bone cement dough while mixing, ensuring complete mixing without air inclusions that would compromise mechanical properties.
Solution Approach 2:
The vacuum mixing system automatically removes air bubbles during the mixing process without requiring additional manual intervention. The system self-regulates the mixing process to achieve complete mixing while eliminating harmful air inclusions.
3Productivity
If the mixing rod is broken off or pulled out after mixing, then the mixing function is completed, but additional working steps are required and the process time increases
Solution Approach 1:
The mixing rod is integrated with the extrusion device, combining the mixing function and extrusion function into a single component. After mixing, the same mixing rod automatically positions itself to extrude the bone cement, eliminating the need for separate removal and extrusion steps.
Solution Approach 2:
The mixing rod continues its useful action from mixing to extrusion without interruption or removal. The transition from mixing to extrusion is seamless, maintaining continuous productive action and eliminating time-consuming intermediate steps.
4Ease of operation
If separate extrusion devices are used, then the bone cement can be extruded, but the extrusion devices must be connected reversibly, cleaned, and re-sterilized increasing complexity
Solution Approach 1:
The extrusion function is merged into the integrated applicator device, eliminating the need for separate extrusion devices that require connection, disconnection, cleaning, and sterilization. The single integrated device performs extrusion directly from the mixing chamber.
Solution Approach 2:
The integrated applicator appears to be designed as a disposable unit that can be discarded after use, eliminating the need for cleaning and re-sterilization of complex extrusion devices. This single-use approach simplifies operation and reduces infection risk.
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
This solution eliminates the need for external devices, reduces the risk of leakage, simplifies the mixing process, and ensures complete mixing of the bone cement, enhancing the efficiency and reliability of the application during procedures like arthroplasty, vertebroplasty, and kyphoplasty.
Implementation Method 1
Mixing the powder component and the monomer component and swelling of the polymers of the powder component in the methylmethacrylate generates dough
Implementation Method 2
the activator, N,N-dimethyl-p-toluidine, reacts with dibenzoylperoxide while forming radicals. The radicals thus formed trigger the radical polymerization of the methylmethacrylate
Implementation Method 3
The radicals thus formed trigger the radical polymerization of the methylmethacrylate. Upon advancing polymerization of the methylmethacrylate, the viscosity of the bone cement dough increases until the bone cement dough solidifies
Data Source
AI summary
A bone cement applicator comprising a cartridge with an internal space. The cartridge has a head with a dispensing opening for expulsion of bone cement, a first thread, a dispensing plunger, a threaded tube having a counter thread engaging the first thread, a receptacle mobile in the threaded tube, and a mixing rod with a mixer fastened to it and arranged in the internal space of the cartridge. The mixing rod is detachably connected to the receptacle and is guided through a feedthrough in the dispensing plunger and is supported in the feedthrough so as to be axially mobile. When detached from the receptacle, the mixing rod can be pushed into the receptacle when the receptacle is propelled in the direction of the cartridge head. A method is also disclosed for production of a bone cement using the bone cement applicator.