Revision Prosthesis Shaft with Distal Cemented Extension
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Solution Overview
Problem
In revision joint endoprosthesis procedures, achieving secure anchoring in the epimetaphyseal area of elongated bones is challenging due to insufficient fastening distance in the diaphysis, leading to loosening and reduced prosthesis lifespan.
Innovation Solution
A revision prosthesis shaft with an epimetaphyseal extension that extends into the distal epimetaphysis for cemented attachment, combining cementless implantation in the epimetaphysis and diaphysis with additional cemented anchorage in the distal epimetaphysis for enhanced stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the shaft length is increased to extend into the diaphysis for cement-free attachment, then the anchoring stability is improved, but the available fastening distance is insufficient when the diaphysis is narrow
Solution Approach 1:
The prosthesis shaft is divided into two functional segments: a proximal shaft portion for cement-free attachment in the epimetaphysis and diaphysis, and a distal extension portion for cemented attachment in the distal epimetaphysis. This segmentation allows each segment to utilize the most appropriate fixation method for its location, resolving the contradiction between shaft length requirements and available fastening distance.
Solution Approach 2:
Different attachment methods are applied to different regions of the prosthesis: the shaft portion has a surface design optimized for cement-free biological fixation, while the extension portion has a surface design optimized for cemented mechanical fixation. This local differentiation allows the prosthesis to achieve reliable anchoring in both the narrow diaphysis and the distal epimetaphysis.
2Ease of manufacture
If the shaft is designed for cement-free attachment to allow bone regeneration, then bone health is improved, but the anchoring security is insufficient in cases with limited fastening distance
Solution Approach 1:
The prosthesis is segmented into a shaft portion for cement-free attachment that promotes bone regeneration, and a separate extension portion for cemented attachment that provides additional anchoring security. This allows the system to simultaneously achieve both bone health benefits and enhanced anchoring reliability.
Solution Approach 2:
The prosthesis employs a composite fixation strategy combining two different attachment methodologies: cement-free biological fixation on the shaft portion and cemented mechanical fixation on the extension portion. This composite approach leverages the advantages of both methods to achieve superior overall performance.
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 provides a stable and secure anchoring system, even in cases with insufficient fastening distance, increasing the durability of the prosthesis and reducing complications by leveraging a previously unused anchoring area.
Implementation Method 1
the extension being designed for attachment with an adhesive, in particular bone cement
Data Source
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AI summary
Revision prosthesis stem of a revision joint endoprosthesis for anchoring in an elongated bone (9), in particular the femur. The surface is designed for cementless fixation in the proximal epimetaphysis (91) and the diaphysis (92) of the bone. According to the invention, a distal epimetaphyseal process (2) is provided at the distal end of the stem (12), the tip of which extends into the distal epimetaphysis (93) of the bone. The process (2) is designed for fixation with an adhesive (3), in particular bone cement, in the distal epimetaphysis (93). The invention combines the advantages of cementless fixation, namely of the stem itself in the diaphysis (92), with those of cemented fixation, namely of the process in the distal epimetaphysis (93). Even in difficult cases where sufficient support could not previously be achieved due to a lack of attachment space in the diaphysis, stable anchorage can be achieved in this way.This increases the safety and longevity of the revision. The invention further extends to a corresponding implantation method.