Modular Rotational Coupler for Endoprosthesis Torsional Stability
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing orthopedic implant technologies, such as humeral and femoral prostheses, fail to adequately address the issue of excessive torsional stresses, leading to dislocation and damage at the affixation site and limited range of motion, particularly in limb-salvage surgical repairs.
Innovation Solution
A modular rotational device with a threaded coupler, housing, and lobe ring system that reduces rotational friction and limits excessive rotation, featuring biocompatible materials and adjustable rotational stops to stabilize the prosthesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed rotational feature is incorporated into existing prosthesis designs, then the prosthesis allows rotation to some degree, but the rotational torque experienced by the intramedullary stem increases and the design lacks flexibility for precise positioning
Solution Approach 1:
The patent transitions from a fixed rotational feature to a dynamically adjustable system where the rotational device can be positioned at different locations along the intramedullary stem. This allows the system to adapt its rotational characteristics based on the specific repair requirements and positioning needs, optimizing both range of motion and torque distribution.
Solution Approach 2:
The rotational device is designed as a separate, modular component that can be independently positioned and attached to the intramedullary stem at various locations. This segmentation allows precise positioning to optimize rotational characteristics and reduces torque on critical areas of the stem.
2Ease of operation
If the rotational device is positioned far from the affixation site, then the prosthesis allows greater range of motion, but the rotational torque on the intramedullary stem increases causing potential loosening
Solution Approach 1:
The system provides dynamic positioning capability where the rotational device can be placed at optimal locations along the stem based on the specific patient anatomy and repair requirements. This allows optimization of the balance between range of motion and fixation stability for each individual case.
Solution Approach 2:
The rotational device can be positioned at specific locations along the intramedullary stem where the local bone quality and anatomical conditions are most favorable. This allows the system to exploit favorable local conditions to minimize torque while maintaining range of motion.
3Reliability
If the rotational device is positioned near the affixation site, then the rotational torque on the stem is reduced improving stability, but the range of motion may be limited
Solution Approach 1:
The adjustable positioning system allows the surgeon to optimize the location of the rotational device based on the specific trade-off between stability and range of motion required for each patient. This dynamic adjustment capability enables fine-tuning of the system to achieve the desired balance.
4Stability of the object's composition
If existing prosthetic designs are used, then the affixation site is stabilized, but excessive torsional stresses cause dislocation and damage at the affixation site
Solution Approach 1:
The rotational device acts as an intermediary element between the intramedillary stem and the prosthetic head, absorbing and distributing torsional stresses. This mediator component protects the affixation site from excessive torsional loads while still allowing necessary rotational movement.
Solution Approach 2:
The system converts the potentially harmful torsional stresses into controlled rotational movement at the rotational device. By providing a dedicated rotational interface, the system transforms what would be damaging stresses at the affixation site into beneficial controlled rotation elsewhere in the prosthesis.
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 device provides improved torsional stability, reducing the risk of dislocation and enhancing the range of motion by minimizing rotational torque and wear, thus improving the functionality and durability of the prosthetic joint.
Implementation Method 1
a proximal sleeve positioned within the housing proximal end axial bore, the proximal sleeve having an axial bore therethrough for receiving the elongated stem, the proximal sleeve reducing the rotational friction of the elongated stem with respect to the housing proximal end; a distal sleeve positioned within the housing distal end axial bore, the distal sleeve having an axial bore therethrough for receiving the elongated stem; the distal sleeve reducing the rotational friction of the elongated stem with respect to the housing distal end
Data Source
AI summary
An improved modular rotational device includes a first and second threaded coupler for affixation along the stem of an endoprosthetic device, for example, a humeral prosthesis or a femoral prosthesis. The rotational device axis of rotation is coaxial with the stem, and its axis of rotation is located in close proximity to the intramedullary stem of the prosthesis or in close proximity to the distal articulation of the prosthesis. A housing has a proximal and distal end with an axial bore therethrough for receiving an elongated stem of the device. A lobe ring may be utilized to limit the axis of rotation of the device. Additional endoprosthetic devices may be attached to male or female threaded couplers, or to Morse tapers. A plurality of suture attachments facilitates attachment of soft tissue thereto.