Knee Joint Preparation with Adjustable Tabs for Minimal Bone Resection

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Solution Overview

Problem

Existing methods for preparing the surfaces of the tibia and femur for prosthetic knee joints require excessive bone resection to accommodate joint components, leading to unnecessary spacing and potential instability.

Innovation Solution

The use of user-operable height adjustable extension tabs integrated into the joint liner or separate preparation plates to establish reference planes, minimizing the need for additional spacing and bone resection by directly engaging with the tibia or femur surfaces, and incorporating pressure sensors and 3D modeling for precise adjustments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional joint components and preparation plates are used separately, then the components can be inserted with adequate spacing, but excessive bone resection is required to accommodate the additional spacing

Engineering Contradiction:
Improvecomponent insertion stabilityVSAvoidbone resection volume
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The patent combines the joint liner and preparation plate into a single integrated component. The preparation plate is formed as part of the joint liner structure, eliminating the need for separate components and the spacing they require. This integration allows the bone resection to be minimized while still providing the necessary preparation functions and component stability.

Inventive Principle:
Principle #5Merging (Combining)

2Manufacturing precision

If height adjustable extension tabs are incorporated into a separate preparation plate, then reference planes can be established for optimal bone profiling, but additional spacing and bone resection are required to accommodate the separate plate

Engineering Contradiction:
Improvebone resection profile accuracyVSAvoidbone resection volume
Core Design Contradiction:
Manufacturing precisionVSLoss of substance

Solution Approach 1:

The height adjustable extension tabs are integrated directly into the joint liner structure rather than being part of a separate preparation plate. This merging allows the reference plane establishment function to be maintained while eliminating the need for additional spacing and excessive bone resection that would be required to accommodate a separate plate with extension tabs.

Inventive Principle:
Principle #5Merging (Combining)

3Ease of manufacture

If adequate spacing is provided between tibia and femur for component insertion, then components can be properly accommodated, but unnecessary bone is removed to create this spacing

Engineering Contradiction:
Improvecomponent assembly feasibilityVSAvoidbone resection volume
Core Design Contradiction:
Ease of manufactureVSLoss of substance

Solution Approach 1:

By forming the preparation plate as an integral part of the joint liner, the patent eliminates the need for additional spacing between tibia and femur components. The integrated structure allows proper component accommodation and assembly while minimizing bone resection to only what is necessary for the actual component insertion, removing unnecessary bone that would have been removed to create spacing for separate components.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP3993718B1An arrangement used in the preparation of bone surfaces of the knee joint for the components of a prosthetic knee joint
Publication Date: 2026.03.25 CABOT JONATHAN PETER
  • EP3993718B1 patent drawingFigure 1a~1b
  • EP3993718B1 patent drawingFigure 2
  • EP3993718B1 patent drawingFigure 3

AI summary

An arrangement for minimizing the amount of bone initially required to be resected off surfaces of a knee joint prepared using a plurality of user-operable adjustable extension tabs that define a stability gap derived from gap measurements taken in each of extension, mid-flexion and flexion, wherein the stability gap is commensurate with a reference plane derivable from the arrangement wherein a final bone resection with a corresponding bone surface with said reference plane provides for optimum balanced angular movement between the tibia component and the femoral component of the prosthetic knee joint post-surgery.