Dual Paste Bone Cement System for Rapid Mixing and Sterilization
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Solution Overview
Problem
Current calcium phosphate bone cement formulations are limited by their need for manual or mechanical mixing, which is time-consuming and user-dependent, and they lack long-term shelf stability and rapid setting properties, especially after gamma radiation sterilization.
Innovation Solution
A dual paste injectable bone cement system comprising an acidic aqueous paste and an alkaline non-aqueous paste, stabilized with synthetic polymers like polyvinyl pyrrolidone and polyethylene glycol, which remain shelf-stable for over a year and rapidly set when mixed during injection, forming a biocompatible and osteoconductive cement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If manual mixing is used for bone cement preparation, then user flexibility is maintained, but the process becomes time-consuming and user-dependent
Solution Approach 1:
The system divides the bone cement into two separate paste components (acidic paste with calcium phosphate powder and alkaline paste with liquid carrier) that are pre-prepared and stored separately. This segmentation allows each component to be optimized independently for stability and performance, while eliminating the need for manual mixing at the time of use.
Solution Approach 2:
The paste components are pre-prepared, pre-measured, and pre-packaged in separate containers before use. The acidic paste contains pre-mixed calcium phosphate powder with binding agents, and the alkaline paste contains pre-mixed liquid carrier with initiators. This preliminary preparation eliminates time-consuming manual mixing and ensures consistent composition.
2Loss of time
If premixed paste formulations are used, then mixing time is reduced, but washout resistance deteriorates in wet field conditions
Solution Approach 1:
The system uses composite material formulations in both paste components. The acidic paste contains calcium phosphate powder combined with binding agents (PVP, PEG, cellulose derivatives). The alkaline paste contains liquid carrier with additives for enhanced cohesiveness. When mixed, these composites form a cement with superior washout resistance in wet field conditions compared to simple premixed formulations.
3Reliability
If gelling agents are added to enhance cohesiveness, then washout resistance improves, but cement hardening speed decreases in the interior mass
Solution Approach 1:
The system applies different functional properties to different regions of the cement. Gelling agents (hydroxymethyl cellulose, carboxymethyl cellulose, chitosan, collagen, gum, gelatin, or alginate) are incorporated to enhance cohesiveness and washout resistance. Simultaneously, setting accelerators (phosphoric acid, citric acid, or their salts) are added to maintain rapid hardening speed even in the interior mass away from the tissue interface.
4Reliability
If dual paste systems are sterilized using gamma radiation, then sterility is achieved, but shelf stability deteriorates due to phase separation
Solution Approach 1:
The system modifies the chemical composition and physical parameters of the paste components to achieve gamma radiation sterilization tolerance. The acidic paste uses calcium phosphate powder with radiation-stable binding agents. The alkaline paste uses radiation-stable liquid carriers (water, glycerol, propylene glycol, ethanol) with appropriate pH buffering agents. These parameter changes enable the dual paste system to maintain shelf stability for at least 6 months after gamma radiation sterilization without phase separation.
5Manufacturing precision
If mechanical mixing systems are used, then mixing consistency is improved, but device complexity and cost increase
Solution Approach 1:
The system merges the two paste components in a single injection device or immediately upon injection. The acidic paste and alkaline paste are delivered through a unified injection mechanism, eliminating the need for separate mixing equipment. This merging approach achieves consistent mixing results while simplifying the overall system and reducing costs compared to complex mechanical mixing systems.
Data Source
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AI summary
The present invention relates to a bone cement precursor system that is presented in the form of two shelf-stable pastes which have been terminally sterilized and are held in separate containers during product transport and storage. When the product is used during surgery, these pastes inject to a site of application through a static mixing device by the action of applied injection force. When the two pastes are mixed, they start to react to each other while injecting out. The resulting composition is highly biocompatible, osteoconductive, injectable, rapid setting and bioresorbable, and is useful in connection with bone repair procedures, for example, in the craniomaxillof acial, trauma and orthopedic areas.