Mould Cap Insert for Uniform Prosthesis Joint Surface
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Solution Overview
Problem
Existing temporary prostheses for hip or shoulder implants often have surface imperfections at the joint between mould halves, leading to reduced mechanical and tribological performances, and surgeons face challenges with imperfectly sized preformed prostheses and limited antibiotic options in bone cement during surgical procedures.
Innovation Solution
A mould with a cap insert that forms a uniform joint surface, allowing for in-surgery customization of the prosthesis head and shaft length, using a mould with interlocking half-shells and adjustable inserts for precise shaping and surface finishing, ensuring a compact and dense head with improved mechanical and tribological performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a mould with two half-shells is used to realize a temporary prosthesis, then the prosthesis can be customized during surgery, but the joint surface between half-shells creates surface imperfections that reduce mechanical and tribological performance
Solution Approach 1:
The mould is divided into two half-shells that can be coupled together, allowing the prosthesis to be customized during surgery while maintaining a uniform joint surface through the specific design of the segmentation interface
Solution Approach 2:
The cap insert is introduced specifically in the head portion of the chamber to provide local quality improvement, ensuring a uniform joint surface exactly where it is needed for tribological performance, while the shaft portion can be customized independently
2Loss of time
If preformed temporary prostheses are ordered weeks before surgery, then the prosthesis can be prepared in advance, but the surgeon has limited freedom in choosing antibiotics and may not find the perfect size match
Solution Approach 1:
The mould and inserts are prepared in advance and brought to the operating room, allowing the surgeon to quickly create a customized prosthesis during surgery with full freedom in antibiotic selection and dimensional adjustment, eliminating the need to order prostheses weeks in advance
Solution Approach 2:
The system transitions from static preformed prostheses to a dynamic in-surgery customization process, where the surgeon can adjust prosthesis dimensions and antibiotic content based on actual surgical findings and patient-specific requirements
3Strength
If the head of the prosthesis is made compact and dense, then mechanical and tribological performance is improved, but surface imperfections at the joint reduce these performances
Solution Approach 1:
The cap insert is specifically positioned in the head portion to ensure uniform joint surface formation exactly where tribological performance is critical, while allowing the shaft portion to be formed independently with appropriate density and strength characteristics
Solution Approach 2:
The cap insert acts as an intermediary element between the two half-shells, mediating the joint interface to ensure a uniform surface that prevents filling defects and recesses, thereby maintaining both compactness and surface finishing quality
Data Source
AI summary
Mould and method for realizing a temporary prosthesis of hip or shoulder, which comprises a shaft and a head. The mould comprises: a first mould portion (1) comprising a first half-shell (2); a second mould portion (3) comprising a second half-shell (4); the first mould portion (1) and the second mould portion (3) being able to be coupled with respect to each other so that the first and second half-shell (2, 4) are counter-faced and define a chamber (5) which conforms a shaft portion (5a), a head portion (5b) and an opening (5c) for injection of a fluid (preferably viscous) material; fixing means (6) for fixing the first and the second portion (1, 3); a first insert (7) comprising a cap portion (8) which is realized as a unique body, is dimensioned to be inserted in the head portion (5b) and is conformed to give shape to the head of the prosthesis. The first mould portion (1), the second mould portion (3) and the first insert (7) are mutually conformed to obtain a temporary prosthesis, when the first mould portion (1) and the second mould portion (3) are coupled together, the first insert (7) is inserted in the head portion (5b) and the fluid (preferably viscous) material is injected in the opening (5c).