Magnetic Actuated Total Joint Prosthesis for Limb Length Adjustment
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current solutions for limb length discrepancies, such as intramedullary lengthening nails, have high complication rates and are not viable for patients who have had or would benefit from total joint arthroplasty, lacking a non-invasive method to adjust limb length without revision surgery.
Innovation Solution
A length-adjustable total joint prosthesis with a stem, housing, and neck, featuring a rotatable magnetic rod and gear system, allowing for non-invasive length modulation through an external magnetic device, enabling precise adjustment of limb length by rotating the magnetic rod to compress or extend the neck within the housing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If intramedullary lengthening nails are used to elongate long bones, then limb length can be increased, but the complication rate increases to 60% with issues such as nail breakage, infection, and fracture
Solution Approach 1:
The patent replaces the traditional mechanical intramedullary nail system with a magnetic field-based actuation system. An external magnetic device generates a magnetic field that interacts with a magnetic rod inside the prosthesis, eliminating the need for invasive intramedullary nails and their associated complications while still achieving limb length adjustment.
Solution Approach 2:
The patent introduces a magnetic rod as an intermediary element that transmits the magnetic field from the external device to the lengthening mechanism. This magnetic intermediary allows non-invasive control of the prosthesis length without requiring direct mechanical connection or intramedullary insertion.
2Ease of operation
If traditional total joint arthroplasty is performed, then joint function is restored, but limb length discrepancy cannot be corrected without revision surgery
Solution Approach 1:
The patent transforms the static total joint prosthesis into a dynamic, adjustable device. The prosthesis incorporates a lengthening mechanism with a screw and gear system that can be actuated post-operatively to adjust the limb length, providing adaptability without requiring revision surgery.
Solution Approach 2:
The patent combines multiple functions into a single prosthesis: joint replacement functionality plus adjustable length modification. The device serves both as a functional joint replacement and as a lengthening device, eliminating the need for separate procedures to address limb length discrepancy.
3Length of moving object
If conservative treatments such as insoles or orthotics are used for limb length discrepancy, then immediate correction is achieved, but biomechanical damage worsens and revision surgery becomes necessary
Solution Approach 1:
The patent enables the patient to self-adjust the prosthesis length post-operatively using an external magnetic device. This allows immediate correction of limb length discrepancy with proper biomechanical alignment, eliminating the need for compensatory insoles or orthotics that cause additional biomechanical damage.
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 provides a non-invasive, precise method to adjust limb length, reducing the need for revision surgery and minimizing complications, while being suitable for patients who have had or would benefit from total joint arthroplasty, thereby improving patient outcomes and quality of life.
Implementation Method 1
operating an external magnetic device comprising a magnetic field of at least one rotatable magnet, wherein the magnetic field rotates the magnetic rod of the prosthesis
Data Source
AI summary
A total joint prosthesis that achieves non-invasive length modification and a method of using the same is provided. A gearbox housing within the implant contains a lengthening mechanism comprising a rotatable magnetic rod mechanically coupled to a lengthening screw through a series of parallel gear sets. The lengthening screw is coupled to an internally threaded implant neck. An external magnetic device containing at least one rotatable magnet produces a magnetic field. After total joint arthroplasty, the magnetic field of the external device forces rotation of the internal magnetic rod, causing rotation of the lengthening screw. Rotation of the lengthening screw causes the neck to either compress toward or extend away from the housing, adjusting the overall length of the implant and limb. This invention thus provides non-invasive means for post-operative limb-length modification after total joint arthroplasty and is useful in treating conditions such as limb-length discrepancy.