Length-Adjustable Bone Implants with Extracorporeal Magnetic Drive
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Solution Overview
Problem
Existing intracorporeal length-adjustable prostheses require skilled personnel for operation due to the risk of incorrect adjustment and potential harm from electric motors, and they are cumbersome and prone to infection when externally controlled.
Innovation Solution
An implant component with a rotatably arranged permanent magnet that uses a static magnetic field for actuation, allowing for precise adjustment through a mechanical drive system that can be operated by non-specialists, including patients, using a drive unit with a rotatable magnetic ring and a bending rod to compensate for angular errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If an electric motor-based adjustment system is used, then extracorporeal adjustability is achieved, but the risk of operating errors increases and skilled personnel are required
Solution Approach 1:
The patent replaces the electric motor-based adjustment system with a purely mechanical system. The adjustment device uses a threaded rod that converts rotational movement into linear movement mechanically, eliminating the need for electric motors and complex control systems. This mechanical substitution reduces the risk of operating errors while maintaining extracorporeal adjustability.
Solution Approach 2:
The patent introduces an intermediary mechanical transmission system consisting of a threaded rod and nut mechanism. This intermediary converts the rotational input from the adjustment device into precise linear displacement of the prosthesis components, providing a reliable and error-resistant adjustment mechanism that does not require skilled operation.
2Length of moving object
If external fixators are used for length adjustment, then length adjustment is achieved, but the device becomes cumbersome and infection risk increases
Solution Approach 1:
The patent employs a nested design where the adjustment device is integrated within the prosthesis structure itself. The threaded rod and adjustment mechanisms are housed within the prosthesis body, allowing length adjustment without requiring external fixators or devices that would protrude from the body and increase infection risk.
Solution Approach 2:
The patent extracts the adjustment functionality from external fixators and integrates it directly into the prosthesis. By taking out the adjustment mechanism from the external environment and embedding it within the implanted prosthesis, the system eliminates the need for external components that would be prone to infection while maintaining length adjustability.
3Productivity
If frequent adjustments are made with electric motor systems, then length equalization is improved, but the complexity of operation and approval increases
Solution Approach 1:
The patent replaces complex electric motor control systems with a simple mechanical adjustment device that can be operated frequently and easily. The mechanical threaded rod system allows for rapid, tool-free adjustments that do not require complex electronic controls or specialized training, enabling frequent adjustments to achieve length equalization.
Solution Approach 2:
The patent designs the adjustment device to be self-operating without requiring external power sources or complex control systems. The mechanical system can be adjusted by the patient or caregiver themselves through simple manual manipulation of the adjustment device, enabling frequent adjustments without involving skilled personnel or complex approval processes.
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
The system enables safe, precise, and frequent adjustments without the need for skilled personnel, reducing the risk of injury and simplifying operation, while allowing for more frequent and gentle length adjustments.
Implementation Method 1
a drive element with a rotatably arranged permanent magnet (3), which responds to a static magnetic field of an extracorporeal drive unit (7)
Data Source
Figure 1~2
Figure 3a~4
Figure 5
AI summary
An extracorporeally length-adjustable implant system comprises – an implant component (1) for an implantable prosthesis, which is embodied to be fastened to a bone (90) to be lengthened and which comprises an adjustment device (2) with two fastening parts (21, 22) that are displaceable relative to one another, each of which is intended for arrangement at a part of the bone (90) to be lengthened, wherein the adjustment device (2) is embodied to distract the two fastening parts (21, 22) that are displaceable relative to one another and comprises a drive element (3) with a permanent magnet arranged in rotationally movable fashion and a mechanism (4) which converts a rotational movement of the permanent magnet into a distracting longitudinal movement of the adjustment device (2); and – an extracorporeal drive unit (7, 7', 7") for the drive element of the implant component (1). The extracorporeal drive unit (7, 7', 7") comprises a rotatably mounted extracorporeal magnetic ring (8) with an interior (80) embodied to receive the bone (90) to be lengthened with the adjustment device (2), and an actuation device (75) which is embodied to rotate the extracorporeal magnetic ring (8) in the ring plane thereof, wherein the extracorporeal magnetic ring (8) is embodied as a permanent magnet structure and has a directed static magnetic field which is stationary with respect to the ring in its interior, and the extracorporeal magnetic ring (8) is mechanically rotated by the actuation device (75). Thus, the invention attains an increase in the adjustment reliability while simplifying the drive unit at the same time, and hence it is rendered suitable for laymen and patients.