Prosthesis Anchor Wedge Sleeve Orientation Control
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Solution Overview
Problem
Existing prosthesis anchors face challenges in maintaining a predetermined orientation within the bone cavity and adjusting prestressing forces effectively, leading to potential detachment and undesirable deflection under high loads.
Innovation Solution
A prosthesis anchor with a rotationally fixed tensioning axis connected to wedge sleeves, allowing for defined force introduction and radial displacement without torque, ensuring stable orientation and optimal force transmission through a clamping mechanism that locks the wedge sleeves in a rotationally fixed manner.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Force
If wedge sleeves are used to expand the prosthesis anchor radially, then fixation force is improved, but orientation stability deteriorates due to torque-induced rotation
Solution Approach 1:
A guide element acts as an intermediary between the wedge sleeves and the clamping axis. This guide element prevents torque transmission from the wedge sleeves to the clamping axis during radial expansion, thereby maintaining orientation stability while still allowing the wedge sleeves to generate the necessary fixation force through radial displacement.
2Ease of operation
If the clamping axis is made loose-fitting in the bone cavity, then insertion ease is improved, but position control deteriorates
Solution Approach 1:
The prosthesis anchor is pre-formed with a specific orientation and geometry before insertion. The guide element and wedge sleeves are pre-configured to control the expansion direction, ensuring that even though the clamping axis fits loosely in the bone cavity for easy insertion, the final positioned orientation is precisely controlled during the expansion phase.
3Reliability
If high prestressing forces are applied to secure fixation, then fixation reliability is improved, but risk of detachment deteriorates due to compression of the deformation element
Solution Approach 1:
The guide element serves as a mediator that distributes and controls the transmission of prestressing forces. It allows high fixation forces to be applied reliably through the wedge mechanism while preventing excessive compression forces from being transmitted to the deformation element, thereby reducing the risk of detachment.
4Strength
If the prosthesis anchor is expanded radially for secure fixation, then anchorage strength is improved, but coaxial alignment deteriorates due to orientation change
Solution Approach 1:
The guide element acts as a mediator that constrains the radial expansion of the wedge sleeves to occur in a controlled manner that maintains coaxial alignment with the bone cavity. It prevents undesirable orientation changes during expansion while still allowing the necessary radial displacement for secure anchorage.
Solution Approach 2:
The guide element introduces asymmetry in the expansion mechanism by providing directional guidance. This asymmetric constraint ensures that the radially expanding wedge sleeves maintain their coaxial alignment with the bone cavity, preventing orientation changes that would compromise the prosthesis-stem alignment.
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 solution maintains the prosthesis anchor's orientation and prevents undesirable shear forces, ensuring secure fixation and improved durability by allowing precise control of radial forces and preventing overloading, while avoiding thermal stress and fluid use.
Implementation Method 1
the resulting friction of the expansion surfaces, ensure a secure and slip-resistant anchoring of the prosthesis
Data Source
Figure 1
Figure 2
Figure 3~5
AI summary
The invention relates to a prosthesis anchor (1) for a prosthesis, in particular an endoprosthesis or exoprosthesis. The prosthesis anchor (1) has a tensioning shaft (2) having a thread portion onto which a tensioning body (5) provided with an internal thread can be screwed. As a result of the relative movement brought about thereby, two wedge-shaped sleeves (6), which have an oblique surface (7) inclined relative to the cross-sectional plane of the tensioning shaft (2), are displaced radially until they eventually abut against an inner wall surface of a bone cavity in a bone.