Dome Patella Components With Decoupled Thickness And Diameter
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Solution Overview
Problem
Conventional dome patella components have a geometric dependency between thickness and size, making it challenging to achieve optimal patellafemoral gap balancing during joint replacement surgeries, as altering thickness requires a corresponding change in component size.
Innovation Solution
The design of implantable orthopaedic knee prostheses featuring dome patella components with a monolithic polyethylene body, where the posterior bearing surface includes a partial hemispherically-shaped peak surface that transitions into a conically-shaped surface, allowing for varying thicknesses and peak diameters while maintaining a common medial/lateral width, decoupling size and thickness dependencies.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the thickness of a dome patella component is reduced to achieve better surgical fit, then the component size (outer diameter) must also be reduced, but this limits the ability to correct patellafemoral gap imbalances
Solution Approach 1:
The patent introduces a new design dimension by varying the peak surface diameter independently from the outer diameter. This allows thickness adjustment without being constrained by the traditional geometric dependency where thickness reduction required size reduction. The peak surface diameter becomes an additional degree of freedom in the design space, enabling independent control of thickness while maintaining outer diameter for surgical correction capability
Solution Approach 2:
The patent changes the geometric parameters of the dome patella component by introducing varying peak surface diameters for components of the same outer diameter. This parameter variation allows the creation of a family of components with identical outer dimensions but different thicknesses and peak curvatures, enabling surgeons to select the optimal thickness for patellafemoral gap balancing without changing the component's outer size
2Length of moving object
If the component size is increased to provide sufficient thickness, then the thickness requirement is met, but the component becomes too large for the given surgical application
Solution Approach 1:
The patent adds the peak surface diameter as an independent design variable, allowing thickness to be adjusted without proportionally increasing the outer diameter. This dimensional independence enables the creation of thinner components that maintain adequate structural thickness through optimized peak curvature rather than increased overall size
Solution Approach 2:
The patent applies local quality by varying the peak surface curvature (peak diameter) independently from the overall component size. This allows the critical thickness region at the peak to be optimized for structural requirements while keeping the outer diameter matched to the surgical application, creating non-uniform thickness distribution that meets both structural and size constraints
3Ease of manufacture
If conventional dome patella components with fixed geometric relationships are used, then manufacturing is simplified, but the ability to independently adjust extension and flexion gaps is limited
Solution Approach 1:
The patent changes the design parameters by creating a series of components with varying peak surface diameters while maintaining constant outer diameter. This parameter family approach allows standard manufacturing processes to be used while producing components with different thicknesses and curvatures, enabling gap balancing versatility without complicating manufacturing
Solution Approach 2:
The patent creates a universal component design where a single outer diameter can serve multiple thickness requirements. This multi-functional approach allows the same component size to address different surgical scenarios (different gap imbalances) by selecting from multiple thickness variants, thereby achieving versatility without requiring multiple size families
Data Source
AI summary
An orthopaedic implant assembly includes a plurality of commonly-sized dome patella components. Each of the commonly-sized dome patella components may be provided in various thicknesses and/or peak surface diameters.