Elastomeric Patella Implant for Full Range Tracking
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Solution Overview
Problem
Current treatments for patella misalignment, dislocation, or instability in the knee joint do not adequately address the full range of joint movement and ensure correct tracking of the patella on the femur, leading to persistent pain and potential arthritis progression.
Innovation Solution
The development of an implant system featuring tension cables, spring components, and elastomeric materials that can be configured to provide variable lateral or medial translation, allowing for proper tracking of the patella throughout the knee joint's range of motion, including a subpatella bar implant to redistribute forces and maintain patella positioning.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If current treatments for patella misalignment are used, then some pain relief may be achieved, but correct tracking of the patella throughout the full range of motion is not ensured
Solution Approach 1:
The implant system employs dynamic components including spring elements and elastomeric materials that can adapt their properties throughout the range of motion. The spring provides variable force that changes as the knee moves through different angles, while the elastomeric material offers compliant support that adjusts to the patella's position, ensuring reliable tracking across the full dynamic range of motion rather than at fixed static positions.
Solution Approach 2:
The system utilizes parameter changes in the spring constant and elastomeric material properties to optimize tracking at different ranges of motion. The spring can be configured with specific stiffness values that change the force characteristics, while the elastomeric material's viscoelastic properties allow it to provide different levels of support during flexion and extension, enabling accurate tracking throughout the complete range of motion.
2Stability of the object's composition
If rigid fixation methods are used to stabilize the patella, then tracking may be improved at certain positions, but the full range of motion and natural joint movement are restricted
Solution Approach 1:
The implant incorporates elastomeric materials that function as flexible structural elements. These elastomeric components provide sufficient stability to guide and stabilize the patella in its correct tracking position while simultaneously allowing the natural range of motion and flexibility of the joint. The flexible nature of the elastomeric material enables it to accommodate joint movement without rigid constraints, maintaining both stability and adaptability.
Solution Approach 2:
The system combines different materials with complementary properties - the spring provides elastic restoring force, the elastomeric material offers compliant support and shock absorption, and any rigid fixation elements are used minimally. This composite approach allows the patella to be stabilized in correct alignment while preserving the full range of motion and natural joint dynamics that would be restricted by purely rigid fixation methods.
3Stability of the object's composition
If force contact between patella and femur is increased to improve tracking, then stability improves, but pain associated with patellofemoral osteoarthritis worsens
Solution Approach 1:
The spring component functions as a counterbalancing element that applies a force opposite to the natural lateral drift of the patella. By providing this counteracting medial force, the spring guides the patella into correct alignment and maintains stable tracking without requiring increased compressive force contact between the patella and femur. The spring's elastic force redirects the patella's path, achieving stability through force redirection rather than force intensification, thereby reducing painful contact forces.
Solution Approach 2:
The elastomeric material acts as an intermediary between the patella and the tracking guidance mechanism. This compliant intermediate layer allows the patella to be guided into correct alignment while cushioning and distributing contact forces, reducing peak stresses and painful force concentrations between the patella and femoral groove. The elastomeric mediator provides both tracking guidance and force distribution, stabilizing the patella while minimizing harmful contact forces that cause pain in osteoarthritic joints.
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 implant system effectively minimizes pain associated with patella misalignment by ensuring correct tracking of the patella, reducing force contact with the femur, and addressing patellofemoral osteoarthritis, thereby improving joint stability and reducing pain across the full range of motion.
Implementation Method 1
elastomeric materials that can be configured to provide variable lateral or medial translation
Implementation Method 2
spring components, and elastomeric materials that can be configured
Implementation Method 3
The cable is configured to apply a force to the patella
Data Source
AI summary
Implant apparatus and methods are directed toward treating conditions involving the knee joint, and the patella specifically, maintain alignment or address misalignment of a patella through a full range of motion of the knee joint Exemplary devices include an elastomeric, Y-shaped device which is secured to the femur and patella on opposite ends thereof by bone anchors. The elastomeric device can be either rotatably or non-rotatably connected to the bone anchors.