Adjustable Endoprosthesis Coupling for Post-Implant Alignment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current endoprosthetic implants for total knee or hip replacements are often inaccurately positioned due to machining errors or misinterpretation of bone surface values, leading to asymmetric wear and reduced service life, as they cannot be adjusted after rigid contact with the bone is established.
Innovation Solution
An adjustable endoprosthesis with a coupling device allowing six degrees of freedom for the second member relative to the first member, enabling surgeons to compensate for inaccuracies by adjusting the implant's geometry post-attachment, using actuable coupling sections that can be manually or automatically controlled, and secured with fixation means or curable substances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the implant is press-fitted or glued to the bone with rigid contact established, then the implant is securely fixed, but the position and orientation cannot be adjusted to compensate for machining inaccuracies
Solution Approach 1:
The coupling device transitions from a static rigid connection to a dynamic adjustable connection, allowing the second member to be moved relative to the first member in six degrees of freedom after implantation, enabling compensation of positioning errors while maintaining secure fixation
Solution Approach 2:
The system allows changing the positional and orientational parameters of the second member relative to the first member through the coupling device, enabling adjustment of the implant geometry to match actual bone position despite machining inaccuracies
2Ease of manufacture
If the implant geometry is fixed during manufacturing, then production is simplified, but any surgical inaccuracies cannot be compensated
Solution Approach 1:
The endoprosthesis is divided into at least two separate members (first member and second member) that can be manufactured independently with standard precision, then coupled together using the adjustable coupling device to achieve the final precise positioning in the patient's body
Solution Approach 2:
The coupling device provides dynamic adjustability after implantation, allowing the surgeon to compensate for machining errors by moving the second member relative to the first member in six degrees of freedom, while maintaining a relatively simple manufacturing process for each individual member
3Adaptability or versatility
If six degrees of freedom are allowed for movement of the second member, then maximum adjustment flexibility is achieved, but the device complexity increases
Solution Approach 1:
The coupling device is divided into multiple independent coupling sections, each capable of generating movement in specific directions or rotations, allowing the six degrees of freedom to be achieved through combination of simpler sectional movements rather than a single complex mechanism
Solution Approach 2:
The coupling device enables dynamic adjustment of the second member relative to the first member in six degrees of freedom, providing maximum adaptability to compensate for surgical inaccuracies while using a modular structure that manages complexity through functional segmentation
Data Source
AI summary
The present application relates to an endoprosthesis including a first member which is connected to a patient's bone; a second member which is adjustably coupled to the first member by a coupling device; wherein the coupling device is configured to generate a movement of the second member relative to the first member. The present application also relates to an artificial joint including such an endoprosthesis and to an endoprosthesis placement system including such an endoprosthesis or artificial joint and a projection device which is configured to project visible light markings, acquired from pre-operational and/or intra-operational patient data, onto the patient and/or the endoprosthesis, thus enabling visible alignment markings of the endoprosthesis to be aligned with respect to projected visible light markings so as to allow a proper adjustment of the endoprosthesis.