Posterior Stabilized Knee Prosthesis Cam Geometry
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current posterior stabilized orthopaedic prostheses for knee replacement surgeries face challenges in replicating natural joint movement, particularly when the posterior cruciate ligament is damaged or deficient, as they restrict or limit posterior movement, which can affect the range and stability of flexion.
Innovation Solution
The design includes a tibial bearing with a spine featuring a posterior cam surface with concave and convex sections, and femoral components with corresponding cam surfaces that articulate with the tibial bearing, allowing for varying ranges of flexion by transitioning contact points during movement, thereby enhancing mobility and stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a posterior stabilized knee prosthesis restricts posterior movement of the tibia relative to the femur, then stability is improved, but the range of flexion is limited
Solution Approach 1:
The cam surface geometry transitions from a fixed restriction to a dynamic system where the contact point moves along the cam surfaces during flexion. The tibial bearing's cam surface and the femoral component's posterior cam work together to provide stability at certain flexion angles while allowing greater range of motion at other angles, resolving the contradiction between stability and flexion range.
2Device complexity
If a single femoral component design is used, then device complexity is reduced, but adaptability to different surgical needs and patient anatomy is limited
Solution Approach 1:
The tibial bearing is designed with a universal cam surface geometry that can work with multiple femoral component types (primary and revision). This allows a single tibial bearing design to serve multiple functions and accommodate different surgical scenarios, reducing the need for multiple specialized components while maintaining adaptability.
Solution Approach 2:
The invention allows for parameter changes in the femoral component's posterior cam geometry between primary and revision components, while maintaining compatibility with the same tibial bearing. This enables customization for different surgical needs through parameter variation rather than complete redesign.
3Ease of manufacture
If the posterior cam surface has only convex or only concave geometry, then manufacturing is simplified, but the contact surface area during flexion is reduced
Solution Approach 1:
The cam surface combines both concave and convex geometric features in a composite structure. This hybrid geometry increases the contact surface area between the tibial bearing and femoral component during flexion, improving load distribution and stability, while remaining manufacturable through conventional machining processes.
Data Source
AI summary
A posterior stabilized knee orthopaedic prosthesis assembly includes a tibial bearing, a primary femoral component, and a revision femoral component. Each of the primary and revision femoral components is configured to separately articulate with the tibial bearing. However, each of the primary and revision femoral components has different geometry. The primary femoral component includes a posterior cam having a posterior cam surfacing including a concave cam surface and a convex cam surface. The revision femoral component includes a posterior cam having only a convex cam surface.