TMJ Prosthesis Design Using Mirrored 3D Skull Anatomy

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Solution Overview

Problem

Designing temporomandibular joint prostheses is challenging due to their complex anatomy and the need for precise functional interaction, often resulting in imperfect approximations without testing articulating components.

Innovation Solution

A method involving a 3D representation of the skull, mirroring healthy structures from a reference side to the affected side, and adapting a 3D model of the condylar head and fossa gliding surface to ensure synchronous movement, using titanium and polyethylene components for low-friction articulation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If a temporomandibular joint prosthesis is designed on the drawing board or computer without testing articulating components, then the design process is simplified and faster, but the functional interaction between articulating components cannot be verified resulting in imperfect approximation of native structures

Engineering Contradiction:
Improvedesign process efficiencyVSAvoidfunctional interaction accuracy
Core Design Contradiction:
ProductivityVSReliability

Solution Approach 1:

The patent creates a virtual model of the patient's skull and prosthesis components before actual implantation, allowing functional testing and optimization of articulating components in silico. This preliminary virtual assembly and movement simulation enables verification of functional interaction without delaying the design process, resolving the contradiction between design efficiency and functional accuracy.

Inventive Principle:
Principle #10Preliminary action

2Reliability

If the prosthesis is designed to replicate native TMJ structures, then functional performance is improved, but the complexity of designing accurate articular surfaces and condylar heads increases significantly

Engineering Contradiction:
Improvefunctional performanceVSAvoiddesign complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses optical scanning and 3D modeling to create precise digital copies of the patient's native TMJ structures. By copying the actual geometry of the condylar head and articular surface from the patient's own anatomy, the system achieves high functional performance without requiring complex manual design, as the native structures serve as the design template.

Inventive Principle:
Principle #26Copying

Solution Approach 2:

The patent employs computer-aided design software to precisely control and adjust geometric parameters of the prosthesis components, allowing optimization of articular surface curvature, condylar head shape, and other critical dimensions. This parametric approach simplifies the design process while maintaining high fidelity to native structures, reducing design complexity without compromising functional performance.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If custom patient-specific prostheses are manufactured, then functional interaction and synchronous movement are improved, but manufacturing time and cost increase

Engineering Contradiction:
Improvesynchronous movement accuracyVSAvoidmanufacturing time
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent uses computer-aided manufacturing to precisely control manufacturing parameters based on the virtual design model. By automating the manufacturing process with CNC machining or additive manufacturing guided by digital models, custom patient-specific prostheses can be produced with high accuracy for synchronous movement while reducing manual intervention time and enabling parallel processing of multiple components.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP4138738B1Computer-implemented method for designing a temporomandibular joint prosthesis, corresponding manufacturing method, computer system, computer program product, data storage medium, data stream, and web server
Publication Date: 2025.11.19 KARL LEIBINGER ASSET MANAGEMENT GMBH & CO KG
  • EP4138738B1 patent drawingFigure 1
  • EP4138738B1 patent drawingFigure 2
  • EP4138738B1 patent drawingFigure 3a~4b

AI summary

The invention relates to a method and a computer system for designing a mandibular joint prosthesis for a patient's skull side (2) to be treated. The essential idea of the method is to match a standardized model of the mandibular joint to a graphic representation of the patient's healthy skull side (1) and to mirror it along a mirror plane onto a graphic representation of the skull side (2) to be treated in order to make corresponding detailed adaptations.