Shoulder Prosthesis Component with Localized Bone Compaction
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Solution Overview
Problem
Current shoulder prosthesis designs based on negative images of the humerus or glenoid can lead to osteolysis and securement issues due to insufficient mechanical stress and poor bone quality, resulting in devitalization and instability of the implant.
Innovation Solution
A shoulder prosthesis component that compactly deforms the cancellous bone internal layer along and around the longitudinal axis, tailored to the preoperative local bone density and quantity, ensuring appropriate mechanical stress and securement by varying compaction rates and structures such as porous, elastic, or bioabsorbable materials.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If the shoulder prosthesis component is designed as a negative image of the humerus or glenoid to match accurate bone anatomy, then the prosthesis can be implanted without removing bone material, optimizing preservation of osseous capital, but this geometrical congruence may lead to devitalization of bone material due to insufficient mechanical stress, causing osteolysis
Solution Approach 1:
The implant body is designed with locally varying compaction capabilities - the peripheral part has different mechanical properties than the central core, allowing differentiated compaction of cancellous bone in different regions. This local quality variation ensures adequate mechanical stress is applied to prevent osteolysis while maintaining anatomical congruence
Solution Approach 2:
The implant body is pre-designed with specific geometric features and material properties that will automatically produce the desired compaction effect on cancellous bone during implantation. The peripheral part and central core are configured in advance to apply appropriate mechanical stress to prevent bone devitalization before any pathological process can occur
2Shape
If the prosthetic body cross-section is reduced to fit ideally into the patient's bone, then the prosthesis fits precisely within the bone, but this may lead to insufficient mechanical stress on covered bone material, causing devitalization and osteolysis
Solution Approach 1:
The peripheral part of the implant body has specifically designed geometric features and material properties that differ from the central core, enabling localized compaction of cancellous bone. This local quality differentiation allows the implant to maintain precise fit while simultaneously applying necessary mechanical stress to prevent bone devitalization
3Reliability
If the shoulder prosthesis component is designed for patients with poor quality cancellous bone, then securement problems are addressed, but additional design complexity is required to ensure both securement and adequate mechanical stress distribution
Solution Approach 1:
The implant body employs local quality variation with a peripheral part having different mechanical and geometric properties than the central core. This allows tailored compaction strategies for different bone quality scenarios without requiring multiple complete redesigns, managing complexity through modular differentiation
Solution Approach 2:
The design allows adjustment of geometric parameters and material properties of the peripheral part and central core to optimize performance for different bone qualities. By varying parameters such as porosity, elasticity, and compaction force distribution, the implant can be adapted to poor quality cancellous bone while maintaining manageable design complexity
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 approach prevents osteolysis and ensures a stable, lifelong implant by applying optimal mechanical stress and securement, even with poor-quality cancellous bone, maintaining bone health and implant stability.
Implementation Method 1
an appropriate mechanical stress having a predetermined value that is both non zero and not too high can be applied by the implantation body of the component on the bone material in the bone
Implementation Method 2
this mechanical stress stimulates the bone material in the bone and thus avoids any devitalization or even osteolysis
Data Source
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AI summary
The shoulder prosthesis component (10; 20; 30; 40) comprises an implantation body (11; 21; 31; 41), which defines an implantation axis (X11; X21; X31; X41) and which is designed to be received within a bone (H; G) of a patient that includes a cortical bone external layer (H1; G1) and a cancellous bone internal layer (H2; G2), and to compact therein the cancellous bone internal layer in a planned manner that is differentiated along and around the implantation axis depending on preoperative local bone density and quantity of the cancellous bone internal layer. A method for producing such a shoulder prosthesis component for a patient is also proposed.