Magnetic Hip Prosthesis With Rotatable Femoral Head for Stability
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Solution Overview
Problem
Existing total hip replacement (THR) prostheses face high dislocation rates due to misalignment of the femoral and acetabular components, leading to complications such as impingement, osteolysis, and loosening, with current stabilization methods restricting motion or causing wear and corrosion.
Innovation Solution
A hip prosthesis design featuring an acetabular component with magnets and a rotatable spherical magnet in the femoral component, generating an attractive force to maintain stability throughout the hip's range of motion, reducing the risk of dislocation while avoiding complications associated with conventional stabilization methods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional stabilization methods (posteriorly oriented rim, larger femoral heads, constrained liners, mobile polyethylene) are used to reduce dislocation, then stability is improved, but complications such as impingement, wear, osteolysis, loosening, and restricted range of motion occur
Solution Approach 1:
The patent replaces mechanical stabilization methods (physical constraints like posterior rims, constrained liners, and mobile polyethylene components) with a magnetic field-based stabilization system. Magnets embedded in the acetabular component and femoral head generate magnetic attraction forces to maintain component alignment and prevent dislocation without physical contact, thereby eliminating impingement, wear, and osteolysis complications associated with mechanical contact.
Solution Approach 2:
The magnetic field acts as an intermediary force between the acetabular component and femoral head. Instead of direct mechanical contact for stabilization, the magnetic field mediates the interaction, providing attractive forces that maintain proper alignment and prevent dislocation while allowing natural range of motion without mechanical constraint.
2Reliability
If larger femoral component heads are used to improve stability and reduce dislocation, then head-to-neck ratio is improved and impingement is reduced, but liner wear increases leading to osteolysis and loosening
Solution Approach 1:
The magnetic stabilization system eliminates the need for larger femoral heads that would otherwise be required to improve stability through increased head-to-neck ratio. By using magnetic attraction forces, the patent maintains stability with standard-sized heads, thereby preventing the accelerated liner wear and subsequent osteolysis that result from using oversized components.
3Reliability
If constrained femoral head-polyethylene liner is used to restore stability in revision THR, then dislocation is reduced, but range of motion is restricted and impingement increases leading to stress transmission and liner damage
Solution Approach 1:
The patent replaces constrained mechanical liners that restrict range of motion with a magnetic field-based stabilization system. The magnetic attraction forces provide stability and prevent dislocation while allowing the full natural range of motion, as the magnetic field exerts forces without physical constraint on component movement.
4Ease of operation
If mobile polyethylene component is used to provide greater effective head size, then range of motion is improved and impingement is reduced, but polyethylene wear and corrosion at femoral head-neck interface increase
Solution Approach 1:
The magnetic stabilization system eliminates the need for mobile polyethylene components that provide greater effective head size. By using magnetic attraction forces for stability, the patent maintains full range of motion without the polyethylene wear and corrosion issues that result from using mobile polyethylene components.
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 design provides enhanced stability and reduces the incidence of dislocation, impingement, and osteolysis, maintaining the range of motion and minimizing wear and corrosion issues.
Implementation Method 1
The acetabular component comprises one or more magnets and the femoral component comprises a rotatable spherical magnet. An attractive force is generated between the one or more magnets of the acetabular component and the spherical magnet of the femoral component.
Data Source
Figure 1A~1B
Figure 2A
Figure 2B
AI summary
A hip prosthesis that comprises an acetabular component (1) and a femoral component (21). The acetabular component comprises a shell (2) and optionally a liner (9). The shell has an approximate shape of a hollowed spherical cap, in which the shell comprises one or more magnets (13). The femoral component comprises a stem portion (22), a neck portion (25) that is joined to the stem portion, and a spherical head (28) that is affixed to the neck portion and comprises a spherical magnet (34) that is rotatable within the spherical head. The acetabular component is configured to receive all or a portion of the spherical head of the femoral component. Further, the one or more magnets of the acetabular component and the spherical magnet of the spherical head of the femoral component are oriented to generate an attractive force therebetween.