Finger Joint Implant with Bone Shield and Compensation Mechanism

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Solution Overview

Problem

Existing finger joint implants face issues such as loosening, increased wear, and fracture due to uneven loading and bone ingrowth, which can lead to impaired functionality and reduced lifespan.

Innovation Solution

A finger joint implant design featuring a first and second component with anchoring sections and a bone shield, along with a compensation mechanism allowing relative movement between components, to mimic the kinematics of a native finger joint and reduce wear and bone ingrowth.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a shaft is inserted in the direction of the central axis of the finger joints, then the joint implant can be anchored securely, but a large amount of bone substance is sacrificed

Engineering Contradiction:
Improveanchoring stabilityVSAvoidbone substance
Core Design Contradiction:
StrengthVSLoss of substance

Solution Approach 1:

The implant system is divided into two separate components: a shaftless joint prosthesis and a separate anchoring element. The joint prosthesis contains only the articulating surfaces, while the anchoring element is inserted into the bone and connects to the joint prosthesis, eliminating the need for a central shaft and preserving bone substance.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The anchoring function is extracted from the joint prosthesis itself and implemented through a separate anchoring element. This allows the joint prosthesis to be shaftless, removing the harmful central shaft that causes bone loss while maintaining secure anchoring through the separate element.

Inventive Principle:
Principle #2Taking out (Extraction)

2Ease of manufacture

If the finger joint is luxated laterally during implantation, then the joint implant can be inserted, but the extensor tendon apparatus, flexor tendons and collateral ligaments are affected

Engineering Contradiction:
Improveimplantation feasibilityVSAvoidtendon and ligament damage
Core Design Contradiction:
Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The anchoring element is inserted into the bone through a lateral approach before the joint prosthesis is assembled and attached. This preliminary insertion creates the necessary access pathway without requiring lateral luxation of the joint, thereby protecting the tendons and ligaments from damage.

Inventive Principle:
Principle #10Preliminary action

3Ease of operation

If the axis of the finger joint is not fixed in position, then the implantation is simpler, but the movement can cause loosening, increased wear or fracture

Engineering Contradiction:
Improveimplantation simplicityVSAvoidimplant stability
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The system allows dynamic adjustment of the joint prosthesis position relative to the anchoring element through a compensation mechanism. This mechanism accommodates positional variations and movements while maintaining stable anchoring, preventing loosening and fracture by adapting to physiological joint movements.

Inventive Principle:
Principle #15Dynamics

Data Source

PatentEP3928747B1Interphalangeal joint implant
Publication Date: 2025.04.16 WALDEMAR LINK GMBH & CO KG
  • EP3928747B1 patent drawingFigure 1~2
  • EP3928747B1 patent drawingFigure 3~4
  • EP3928747B1 patent drawingFigure 5~6

AI summary

The present disclosure provides a joint implant for replacing a finger joint. The joint implant comprises a first component (1), wherein the first component comprises a first joint section (20) and a first anchoring section (10), the first joint section including a concave joint surface (21) about a first axis (A1) and the first anchoring section extending transverse to the first axis. The joint implant also comprises a second component (2), wherein the second component comprises a second joint section (40) and a second anchoring section (30), the second joint section including a circumferential surface (42) about a second axis (A2) and the second anchoring section extending transverse to the second axis, wherein the circumferential surface comprises a convex joint surface (41) that is configured to act as a hinge joint with the concave joint surface of the first joint section. The second component further comprises a bone shield (60) arranged between the second joint section and the second anchoring section, wherein the bone shield extends about a third axis (A3) and partially covers the circumferential surface of the second joint section with a gap being formed between the circumferential surface and the bone shield.