Surgical Navigation Tensor for Ligament Balancing

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Solution Overview

Problem

Soft tissue balancing during knee surgery is imprecise due to the lack of precise methods to quantify ligament tension, particularly in total knee arthroplasty procedures, where arthritis complicates the assessment of ligament contracture and required soft tissue release.

Innovation Solution

A tensor device for surgical navigation systems, comprising bone engaging members and a force-applying mechanism with a sensor to detect and transmit applied forces, allowing for precise ligament balancing and bone distraction, integrated with a surgical navigation system to provide real-time feedback for optimal ligament tension and bone alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If traditional soft tissue balancing methods are used without quantitative measurement, then the surgical procedure is simpler, but the precision of ligament tension assessment deteriorates

Engineering Contradiction:

Improveligament tension measurement precisionVSAvoidsurgical device complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces traditional mechanical soft tissue balancing methods with a sensor-based measurement system. Load cells and force sensors are integrated into the tensor device to quantitatively measure ligament tension forces, replacing subjective mechanical assessment with precise electronic measurement. This allows real-time feedback on ligament balance during surgery.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an intermediary measurement system between the surgical tensor device and the surgeon's assessment. Sensors and load cells act as intermediaries that translate mechanical ligament forces into measurable electrical signals, which are then processed and displayed to guide the soft tissue balancing procedure.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Manufacturing precision

If tensors are applied only after bone cuts are complete, then the surgical workflow is simpler, but the ability to guide bone cuts deteriorates

Engineering Contradiction:

Improvebone cut precisionVSAvoidsurgical workflow efficiency

Core Design Contradiction:

Manufacturing precisionVSProductivity

Solution Approach 1:

The patent implements preliminary soft tissue balancing assessment using the tensor device with integrated sensors before finalizing bone cuts. This allows the surgeon to measure ligament tensions and adjust bone cuts accordingly, ensuring proper ligament balance is achieved during the surgical procedure rather than as a post-hoc check.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent incorporates real-time feedback through sensors that measure ligament tension forces during the surgical procedure. This feedback loop allows the surgeon to adjust bone cuts and soft tissue releases based on quantitative measurement data, improving the precision of bone cuts while maintaining efficient workflow through immediate guidance.

Inventive Principle:

Principle #23Feedback

3Measurement precision

If quantitative measurement of ligament tension is implemented, then the accuracy of soft tissue balancing improves, but the complexity of the measurement system increases

Engineering Contradiction:

Improveligament tension quantification accuracyVSAvoidmeasurement system complexity

Core Design Contradiction:

Measurement precisionVSDifficulty of detecting and measuring

Solution Approach 1:

The patent uses electronic sensors and load cells to replace complex manual measurement techniques. The electronic measurement system provides direct numerical readouts of ligament tension forces, simplifying the measurement process while improving accuracy compared to traditional mechanical assessment methods.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The tensor device with integrated sensors performs self-measurement of ligament tensions without requiring additional external measurement equipment. The system automatically measures and displays force values, eliminating the need for separate measurement procedures and reducing overall system complexity.

Inventive Principle:

Principle #25Self-service

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables precise ligament balancing and bone distraction, improving the accuracy of knee joint alignment and reducing stress on the prosthesis, thereby extending its lifespan and minimizing pain and discomfort.

Implementation Method 1

a sensor configured to detect the value of the force applied by the force-applying mechanism

Methodology Applied

Scientific EffectForce sensing: Force

Data Source

PatentUS8323290B2Tensor for use in surgical navigation

Publication Date: 2012.12.04 BIOMET MFG LLC

AI summary

A tensor for use with a surgical navigation system is provided. The tensor comprises a first bone engaging member engageable with a first bone and a second bone engaging member engageable with a second bone. A force-applying mechanism is configured to forcibly move the first and second bone engaging members relative to one another and a sensor detects the value of the force applied by the force-applying mechanism. A transmitter communicates a parameter associated with the tensor to the surgical navigation system.