Spacer Casting Mold with Metal Core and Flange
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Solution Overview
Problem
Current devices for producing hip and shoulder spacers with bone cement paste face challenges such as the need for high viscosity bone cement, risk of cement paste flowing back out, and limited adjustability of spacer head sizes and neck lengths, which complicates the production process and requires significant manual force.
Innovation Solution
A two-part casting mold system with a metal core and biocompatible materials, allowing for the production of spacers with adjustable head diameters and neck lengths using both low and high-viscosity bone cement paste without the need for high pressure, and featuring a flange for secure positioning and easy assembly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If high-viscosity bone cement paste is used, then the spacer structure is more stable, but the cement paste flows back out of the mold during production
Solution Approach 1:
The mold is pre-filled with bone cement paste before the metal core is inserted. This preliminary action ensures that the mold cavity is already filled, preventing the high-viscosity cement from flowing back out when the core is added, while still achieving stable spacer structure
Solution Approach 2:
Instead of inserting the metal core first and then filling with cement (conventional method), the invention inverts the sequence by filling the mold with cement first and then inserting the core. This reversal prevents cement overflow while maintaining structural stability
2Adaptability or versatility
If adjustable head diameters and neck lengths are implemented, then the device versatility is improved, but the device complexity increases
Solution Approach 1:
The mold system is divided into separate components: a reusable base mold and interchangeable adjustable inserts. These inserts can be easily swapped to change head diameter and neck length specifications, providing versatility without requiring a completely different mold for each configuration
Solution Approach 2:
The mold includes adjustable elements that can be dynamically reconfigured for different spacer specifications. The adjustable inserts allow the mold to adapt to various head diameters and neck lengths through simple mechanical adjustments rather than fixed complex structures
3Manufacturing precision
If high pressure is applied during cement injection, then the mold filling is complete, but the risk of cement leakage and equipment cost increases
Solution Approach 1:
The mold is pre-filled with bone cement paste before the metal core is inserted. This preliminary action ensures that the mold cavity is already filled, preventing the high-viscosity cement from flowing back out when the core is added, while still achieving stable spacer structure
Solution Approach 2:
The invention changes the viscosity parameter of the bone cement paste by selecting appropriate cement formulations. This parameter change allows the cement to be injected at lower pressures while still achieving complete mold filling, reducing the risk of leakage and equipment 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
Enables the production of spacers with customizable dimensions and reduced manual effort, avoiding the need for high-pressure injection and costly mechanical post-processing, while ensuring the spacers are reinforced with a metal core for mechanical stability.
Implementation Method 1
a bone cement paste which then cure by polymerization with the assistance of the monomer liquid added to the cement powder
Data Source
AI summary
The invention relates to a device for producing a spacer havinga stem mold (1) which has an inner space (2), wherein the inner space (2) is accessible via a proximal opening (3) and wherein the stem mold (1) has a proximal wall (4) which peripherally delimits the proximal opening (3) of the stem mold (1),a head mold (5) which has in the interior thereof a hollow space (6), wherein the hollow space (6) has a spherical surface-shaped inner surface (7) and is accessible via a distal opening (8), wherein the head mold (5) has a distal wall (9) which peripherally delimits the distal opening (8) of the head mold (5),a metal core (10) which has a stem part (12), a head part (14) and a flange (16), wherein the flange (16) projects out from the metal core (10), is arranged between the stem part (12) and the head part (14) and has a proximal surface (18) and a distal surface (20),wherein the stem mold (1) and the stem part (12) are shaped such that the stem part (12) is arranged in the inner space (2), when the proximal wall (4) is resting against the distal surface (20), and wherein the head mold (5) and the head part (14) are shaped such that the head part (14) is arranged in the hollow space (6), when the distal wall (9) is resting against the proximal surface (18).The invention also relates to a set with such a device and to a method for producing spacers with such a device.