Knee Prosthesis Guide Channel for Tibia Lengthening

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Solution Overview

Problem

Current implantable knee prostheses require repeated major surgical interventions for lengthening the tibia, which increases the risk of infection and does not allow for minimally invasive techniques without decoupling the prosthesis, especially when leg length discrepancy affects the lower leg.

Innovation Solution

An implantable prosthesis with a femoral and tibial prosthetic element articulated by a joint device, featuring a through-opening and guide channel that aligns with the tibial prosthetic element, enabling the introduction of tools and intramedullary lengthening nails through a small suprapatellar incision, allowing for bone lengthening without decoupling the prosthesis, using a guide sleeve to facilitate tool exchange and stabilize the knee joint.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the prosthesis is designed to allow exchange of shaft anchoring means or intramedullary lengthening nails, then bone lengthening can be performed, but the prosthesis must be decoupled which requires major surgical intervention and increases infection risk

Engineering Contradiction:

Improveability to exchange shaft anchoring means or intramedullary lengthening nailsVSAvoidsurgical intervention complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The prosthesis is divided into separable components: the joint device can be detached from the tibial prosthetic element, and the shaft anchoring means or intramedullary lengthening nail can be independently exchanged through the through-opening without requiring complete prosthesis removal or complex surgical intervention

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A guide channel is introduced as an intermediary structure that facilitates the passage of tools and intramedullary lengthening nails through the joint device and tibial prosthetic element. This guide channel enables minimally invasive access and exchange procedures without requiring major surgical decoupling of the prosthesis

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If repeated major surgical interventions are performed for bone lengthening, then the tibia can be lengthened, but the risk of infection increases

Engineering Contradiction:

Improveability to perform bone lengtheningVSAvoidinfection risk

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

The guide channel acts as a protected pathway that allows tools and intramedullary lengthening nails to be introduced through a small suprapatellar incision. This intermediary structure enables bone lengthening procedures while minimizing exposure to external contaminants and reducing infection risk associated with repeated major surgical interventions

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The guide channel is pre-formed as part of the joint device structure, allowing subsequent exchange of shaft anchoring means or intramedullary lengthening nails through a predetermined, controlled pathway. This preliminary preparation enables future minimally invasive interventions without requiring repeated major surgical exposures

Inventive Principle:

Principle #10Preliminary action

3Stability of the object's composition

If the tibial shaft anchoring means is smooth to allow bone growth, then bone can grow into it, but it prevents exchange for intramedullary lengthening nails

Engineering Contradiction:

Improvebone integration stabilityVSAvoidability to exchange shaft anchoring means

Core Design Contradiction:

Stability of the object's compositionVSAdaptability or versatility

Solution Approach 1:

The shaft anchoring means or intramedullary lengthening nail can be extracted from the tibia through the through-opening in the tibial prosthetic element. This through-opening provides access for removing smooth shaft anchoring means that have allowed bone growth, and for inserting intramedullary lengthening nails through the guide channel without requiring prosthesis decoupling

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The through-opening in the tibial prosthetic element serves multiple functions: it allows initial insertion of smooth shaft anchoring means for bone growth, enables subsequent exchange for intramedullary lengthening nails through the guide channel, and provides access for tool passage. This universal opening design accommodates different treatment stages and requirements

Inventive Principle:

Principle #6Universality (Multi-functionality)

Data Source

PatentUS10136996B2Implantable prosthesis for replacing the human knee joint

Publication Date: 2018.11.27 BAUMGART RAINER

AI summary

The implantable prosthesis for replacing a human knee joint comprises a femoral prosthetic element (12) and a tibial prosthetic element (14) which are articulated with one another by means of a joint device (30) for the purpose of executing a knee bend. The tibial prosthetic element (14) has a through-opening (40) for the passage of a tool (84), a rod-like shaft anchoring part (32) or an intramedullary lengthening nail (80). In order to reduce the extent of a surgical intervention and thus the risk of infection also for the lengthening of the tibia, the joint device (30) is designed such that it forms a guide channel (42) for the passage of the tool (84), the rod-like shaft anchoring part (32) or the intramedullary lengthening nail (80) from the outside, which guide channel is in alignment with the through-opening (40) and is in connection therewith when the tibial prosthetic element (14) and the femoral prosthetic element (12) are arranged at a predetermined angle relative to one another in a functional position corresponding to a knee bend.