Transition resection guide for bicompartmental knee implant alignment

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Solution Overview

Problem

Current methods for bicompartmental knee replacement surgeries lack specific instrumentation to accurately mark the transition boundary between the implant and bone, leading to challenges in achieving proper articulation and smooth transition between the medial and lateral compartments of the knee.

Innovation Solution

A femoral system comprising a femoral component and a transition resection guide that allows for precise anterior and distal resections on the femur, enabling proper positioning of the implant to ensure smooth transition between bone and implant surfaces, while preserving the healthy lateral condyle and cruciate ligaments.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional total knee replacement is performed, then complete joint replacement is achieved, but healthy lateral condyle and ligaments are sacrificed

Engineering Contradiction:
Improvejoint replacement completenessVSAvoidhealthy bone and ligament loss
Core Design Contradiction:
ReliabilityVSLoss of substance

Solution Approach 1:

The knee replacement is segmented into two compartments: the diseased medial compartment is replaced with a prosthesis, while the healthy lateral compartment is preserved. This selective replacement approach allows treatment of the affected area without sacrificing healthy tissue, directly resolving the contradiction between complete joint replacement and preservation of healthy structures.

Inventive Principle:
Principle #1Segmentation

2Ease of manufacture

If bicompartmental knee replacement is performed without specific instrumentation, then minimally invasive surgery is achieved, but accurate transition boundary marking is lost

Engineering Contradiction:
Improvesurgical invasivenessVSAvoidtransition boundary accuracy
Core Design Contradiction:
Ease of manufactureVSMeasurement precision

Solution Approach 1:

A transition resection guide acts as an intermediary tool between the surgeon and the bone, providing a mechanical means to accurately mark and resect the transition boundary. The guide includes a guide surface that contacts the bone and a reference feature that aligns with the anterior resection, enabling precise boundary definition without complex instrumentation or extensive surgical exposure.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Ease of operation

If transition resection is performed without proper guidance, then surgical simplicity is maintained, but smooth transition between implant and bone is compromised

Engineering Contradiction:
Improvesurgical procedure simplicityVSAvoidsurface transition smoothness
Core Design Contradiction:
Ease of operationVSManufacturing precision

Solution Approach 1:

The transition resection guide is positioned and the transition boundary is marked before the actual resection is performed. This preliminary action allows the surgeon to plan and execute the resection with precision, ensuring a smooth transition surface between the implant and bone while maintaining surgical simplicity through a systematic, pre-planned approach.

Inventive Principle:
Principle #10Preliminary action

Data Source

PatentEP3216426B1Implants with transition surfaces and related resection guide
Publication Date: 2019.06.12 SMITH & NEPHEW INC
  • EP3216426B1 patent drawingFigure 1~2B
  • EP3216426B1 patent drawingFigure 2C
  • EP3216426B1 patent drawingFigure 2D

AI summary

Implants, and processes for installing them, which replace the medial condyle and portions of the patellofemoral channel but preferably not portions of the lateral condyle that articulate relative to the tibia. Processes are provided which allow proper location and orientation of an anterior resection and a distal resection on the femur, which make use of a transition point which can be designated on the bone, for navigating proper positioning of such implants. Proper positioning of the implant relative to the femur for insuring a smooth transition between lateral portions of the implant and the lateral condyle is thus reduced to determining proper medial / lateral location of the implant on the anterior and distal resections. Such implants and processes can allow, among other things, for controlled location and orientation of an implant on the bone which saves lateral compartment bone, which eliminates the need to sacrifice the anterior and posterior cruciate ligaments, and which is adapted for minimally invasive surgery with its attendant benefits.