Knee Prosthesis Tibial Plate Insert Connection

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Solution Overview

Problem

Existing knee prosthesis systems with fixed bearing or insert designs are difficult to mass-produce and have a limited lifespan due to rapid wear of the soft polyethylene insert compared to the harder metal plate, leading to premature degradation.

Innovation Solution

A tibial plate-insert connection is designed using a stud and corresponding cavity with rear and front stops, along with a snap-fastening rib and groove, facilitating simple manufacturing and enhanced resistance to wear, ensuring a longer service life.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a complex structure is used to connect the insert to the plateau, then the connection strength is improved, but the manufacturing complexity increases

Engineering Contradiction:
Improveconnection strengthVSAvoidstructure complexity
Core Design Contradiction:
StrengthVSDevice complexity

Solution Approach 1:

The connection system is divided into discrete functional elements: a central stud for vertical anchoring, peripheral stops for rotational constraint, and a rib-groove snap-fit mechanism. This segmentation allows each element to be optimized independently while simplifying manufacturing compared to monolithic complex structures.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The stud is nested within a cavity in the insert, with the rib extending from the stud and engaging with a groove in the cavity wall. This nested arrangement creates a compact, multi-functional connection system that reduces overall structural complexity while maintaining connection strength.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Reliability

If the insert is made of soft polyethylene material, then the comfort and biocompatibility are improved, but the wear resistance deteriorates

Engineering Contradiction:
ImprovebiocompatibilityVSAvoidservice life
Core Design Contradiction:
ReliabilityVSDuration of action of stationary object

Solution Approach 1:

The prosthesis uses a composite material system where the insert is made of soft polyethylene for biocompatibility and comfort, while the plateau and connection elements are made of harder metal materials for wear resistance and structural strength. This material composite approach allows each component to optimize its properties for its specific function.

Inventive Principle:
Principle #40Composite materials

Data Source

PatentEP3338740B1Knee prosthesis with fixed bearing
Publication Date: 2019.07.24 XNOV IP
  • EP3338740B1 patent drawingFigure 1~2
  • EP3338740B1 patent drawingFigure 3~4

AI summary

Assembly for knee prosthesis, comprising a tibial plateau (4) and an insert (2), the tibial plateau having a superior face, on which the insert is disposed, and an inferior face intended to be secured to the tibia, in particular by anchoring the plateau to the proximal or superior end of the tibia by means of a keel (5) from the plateau, characterized in that a stud (6), in particular cylindrical, in particular circular, protrudes from the superior face of the tibial plateau and is received in a cavity (26), formed in the insert, and at least two stops (8, 9, 10) respectively posterior and anterior, protrude from the superior face of the tibial plateau, each stop (8, 9, 10) being received in a cavity (28, 29, 30) formed in the tibial insert, the at least two stops being disposed on either side of the stud in the anteroposterior direction.