Trial Knee Implant Rotation Reference for Intraoperative Alignment

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Solution Overview

Problem

Current methods for evaluating femoral-tibial rotation during knee arthroplasty surgery are cumbersome, costly, and expose patients and medical staff to radiation, and require specialized equipment, leading to inefficiencies and potential patient discomfort due to improper rotation alignment.

Innovation Solution

A tibial-femoral trial implant with a graduated reference system indicating the relative angular deviation between femoral and tibial trial inserts, allowing direct intra-operative verification of the correct 20° external rotation of the femur with respect to the tibia without the need for robotic systems or additional imaging.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If robotic systems or navigation systems are used to evaluate femoral-tibial rotation, then measurement precision is improved, but device complexity and cost increase

Engineering Contradiction:

Improvefemoral-tibial rotation measurementVSAvoidrobotic system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent uses a graduated reference system with notches and markings that creates a simplified visual copy of the rotation measurement function. Instead of using complex robotic systems with sensors and computers, the invention replicates the measurement capability through a mechanical reference system with graduated notches that directly indicate rotation angles, making the system much simpler while maintaining measurement precision for the specific purpose of evaluating femoral-tibial rotation.

Inventive Principle:

Principle #26Copying

Solution Approach 2:

The patent extracts the essential measurement function from complex robotic systems by isolating the rotation measurement capability into a standalone graduated reference system. This extracted function is implemented through simple notches and markings on the trial implant components, removing unnecessary complexity while preserving the core measurement capability for evaluating femoral-tibial rotation during surgery.

Inventive Principle:

Principle #2Taking out (Extraction)

2Measurement precision

If computed tomography or magnetic resonance imaging are used to check femoral-tibial alignment, then measurement precision is improved, but loss of time increases

Engineering Contradiction:

Improvefemoral-tibial alignment measurementVSAvoidpre-operative time

Core Design Contradiction:

Measurement precisionVSLoss of time

Solution Approach 1:

The patent incorporates the measurement function directly into the trial implant components that are placed during surgery. The graduated reference system with notches and markings is built into the trial femoral and tibial components, allowing immediate measurement of femoral-tibial rotation and alignment during the surgical procedure itself, eliminating the need for separate pre-operative CT or MRI scans and significantly reducing preparation time.

Inventive Principle:

Principle #10Preliminary action

3Difficulty of detecting and measuring

If radiography is used to evaluate knee movement, then measurement capability is provided, but object-affected harmful factors increase

Engineering Contradiction:

Improveknee movement measurementVSAvoidradiation exposure

Core Design Contradiction:

Difficulty of detecting and measuringVSObject-affected harmful factors

Solution Approach 1:

The patent creates a visual copy of the measurement function through the graduated reference system with notches and markings on the trial implant. This mechanical reference system allows direct visual assessment of femoral-tibial rotation and alignment during surgery without requiring radiographic imaging, thereby eliminating radiation exposure to the patient and medical staff while maintaining the ability to detect and measure knee movement parameters.

Inventive Principle:

Principle #26Copying

4Ease of operation

If trial implants without reference system are used, then ease of operation is improved, but measurement precision deteriorates

Engineering Contradiction:

Improvetrial implant installationVSAvoidfemoral-tibial rotation measurement

Core Design Contradiction:

Ease of operationVSMeasurement precision

Solution Approach 1:

The patent merges the trial implant components with the measurement reference system by integrating the graduated notches and markings directly into the trial femoral and tibial components. This combination allows the trial implant to serve dual purposes: providing mechanical guidance during surgery while simultaneously enabling precise measurement of femoral-tibial rotation and alignment, thus maintaining ease of operation while achieving measurement precision.

Inventive Principle:

Principle #5Merging (Combining)

Data Source

PatentUS12514717B2Tibio-femoral trial implant

Publication Date: 2026.01.06 MEDACTA INT SA

AI summary

A tibial-femoral trial implant comprises a femoral trial insert, which comprises a medial condyle and a lateral condyle, and a tibial trial insert, which comprises a medial plate and a lateral plate. The implant further comprises a graduated reference system adapted to indicate the relative angular deviation between the femoral trial insert and the tibial trial insert about a vertical axis, passing through the center of a sphere defining the medial condyle of the femoral trial insert, following a roto-translational movement of the femoral trial insert from a first position, identifying a knee extension position, to a second position, identifying a knee flexion position.