Modular Middle Ear Prosthesis with Adjustable Plug Insert
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Solution Overview
Problem
The challenge in middle ear prosthesis reconstruction lies in selecting the correct prosthesis length and achieving a stable, optimal geometric coupling to the footplate of the stirrup, as anatomical variations require adaptable solutions that are not easily addressed by existing prostheses, which often result in instability or dislocation and necessitate a wide range of prostheses in stock.
Innovation Solution
A middle ear prosthesis design featuring a receiving part with an elongate cavity for the plug element, allowing for adjustable length and geometric adaptation during surgery using insert parts of varying lengths, which can be wedged or heated for precise fitting, and materials with shape memory for flexibility and stability, enabling optimal coupling without the need for multiple prostheses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a fixed-length prosthesis is used, then the structure is simple, but it cannot adapt to anatomical variations and may cause instability or dislocation
Solution Approach 1:
The prosthesis is divided into a receiving part (integrally connected to the shaft) and an insert part (with plug element). The insert part can be selected in different lengths and inserted into the receiving part to achieve the required overall length. This segmentation allows adaptation to anatomical variations while keeping each component relatively simple in structure.
2Adaptability or versatility
If multiple prostheses of different lengths are kept in stock, then anatomical variations can be addressed, but inventory complexity and selection time increase
Solution Approach 1:
A single receiving part design can accommodate multiple insert parts of different lengths. The standardized receiving part with elongate cavity serves as a universal interface that accepts various insert parts, eliminating the need to stock multiple complete prosthesis variants. This reduces inventory complexity while maintaining the ability to address anatomical variations.
3Reliability
If the receiving part has a tight fit for the plug element, then stability is improved, but insertion and adjustment during surgery become difficult
Solution Approach 1:
The elongate cavity provides initial clearance that allows easy insertion and adjustment of the plug element during surgery. Once positioned correctly, the plug element can be secured (e.g., through welding or interference fit) to create a stable, rigid connection. This dynamic approach transitions from ease of insertion to stable fixation.
4Ease of operation
If the second coupling element extends far from the prosthesis body, then coupling to the footplate is easier, but the prosthesis becomes more prone to buckling
Solution Approach 1:
The optimal extension length of the second coupling element is determined as a specific parameter range (at most a third of the axial length of the shaft-like prosthesis body). This parameter optimization balances the need for sufficient clearance to accommodate anatomical variations and ease of coupling with the need to maintain structural stability and resist buckling under load.
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 design allows for precise length and geometric adaptation during surgery, preventing postoperative changes and ensuring a stable, flexible fit, reducing the need for multiple prostheses and minimizing complications such as dislocation and material rejection.
Implementation Method 1
an insert part with a plug element that can be inserted into the receiving part coaxially with respect to the longitudinal axis of the shaft-like prosthesis body
Implementation Method 2
the elongate cavity is closed at the end directed away from the insert part and, in the assembled state, acts as an end abutment for the plug element
Data Source
AI summary
A total prosthesis for the middle ear, with a prosthesis body, with a first coupling element for connection of the prosthesis to the tympanic membrane or for coupling to the manubrium, and with a second coupling element for connection to the footplate of the stirrup, which second coupling element has a receiving part, connected rigidly to the prosthesis body, and has an insert part with a plug element that can be inserted coaxially, and with a shoe that is connected rigidly to the plug element and that bears on the footplate of the stirrup, is characterized in that the receiving part has an elongate cavity as a receiving opening with a cylindrical bore which extends axially and encloses the full circumference of the plug element and whose inside diameter is greater than the maximum transverse extent of the plug element, which elongate cavity is closed at the end away from the insert part and acts as an end abutment for the plug element, and in that the second coupling element extends axially by at most a third of the axial length of the prosthesis body. In this way, it is easy to produce a desired defined length of the prosthesis, which also remains fixed after surgery, and it is also possible, during surgery, to react to the specific individual situation of the stirrup bone.