Knee Replacement Surgical Instrument for Rigid Tibial Alignment Transfer

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Solution Overview

Problem

Conventional surgical instruments for knee joint replacement operations face challenges in achieving precise alignment of resection cuts due to complex adjustments and cumulative guiding tolerances, which affect the accuracy of implanting prosthetic joint surfaces.

Innovation Solution

A surgical instrument system with a first and second fastening device, a guiding device, and an alignment rod that allows for a pivotably movable connection, enabling a precise transfer of the femoral reference component alignment to the tibial cutting block, reducing the number of adjustable guides and bearings, and incorporating a display device for intuitive adjustment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple guides and bearings are used to connect components for adjustable movement, then adaptability to anatomical features is improved, but device complexity and guiding tolerance accumulation increase

Engineering Contradiction:

Improveadaptability to anatomical featuresVSAvoidcomplexity of guides and bearings

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

The patent removes the complex system of multiple guides and bearings from the connection between the femoral reference component and tibial cutting block. Instead, it uses a direct rigid connection with integrated alignment features, extracting the unnecessary intermediary elements that caused tolerance accumulation while maintaining adaptability through programmable positioning.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical system of multiple adjustable guides and bearings with a computer-implemented positioning system. The surgical instrument includes memory elements storing preoperative planning data, allowing the system to automatically position components based on digital models rather than relying on complex mechanical adjustment mechanisms.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Adaptability or versatility

If multiple guides and bearings are used for adjustable connection, then adaptability is improved, but manufacturing precision and alignment accuracy deteriorate due to tolerance chain

Engineering Contradiction:

Improveadaptability to anatomical featuresVSAvoidalignment precision of resection cuts

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent eliminates the chain of multiple guiding interfaces that create tolerance accumulation. By using a direct rigid connection between components and incorporating alignment features directly into the instrument structure, it removes the intermediate elements whose manufacturing tolerances would add up, thereby improving overall alignment precision.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical tolerance-based guiding system with a computer-controlled positioning system. Preoperative planning data stored in memory elements provides precise target positions, and the instrument uses direct rigid connections with integrated alignment features to achieve sub-millimeter accuracy without relying on cumulative mechanical tolerances.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Adaptability or versatility

If complex adjustable guides are used, then ease of operation for anatomical adaptation is improved, but ease of operation for adjustment complexity worsens

Engineering Contradiction:

Improveadaptability to anatomical featuresVSAvoidease of adjustment during surgery

Core Design Contradiction:

Adaptability or versatilityVSEase of operation

Solution Approach 1:

The patent replaces complex mechanical adjustment mechanisms with a computer-implemented system that uses preoperative planning data stored in memory elements. The surgical instrument automatically positions components based on digital models, eliminating the need for surgeons to manually adjust multiple guides and bearings during surgery, thereby simplifying the operation while maintaining full adaptability to patient-specific anatomy.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Data Source

PatentUS12408930B2Surgical instrument and surgical instrument system

Publication Date: 2025.09.09 AESCULAP AG

AI summary

A surgical instrument for use in a knee joint replacement operation having a first fastening device, a second fastening device, a guiding device connected at one end to the first fastening device and at the other end to the second fastening device and by which the second fastening device is pivotably movable in a manner guided relative to the first fastening device in a sagittal guiding plane, and an alignment rod configured for alignment with respect to an anterior edge of a tibia. The alignment rod is releasably connected to the second fastening device in a rigid manner.