Robotic Ligament Evaluation for Precise Joint Balancing

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Solution Overview

Problem

Traditional manual evaluation of soft tissue during partial or total joint replacement surgeries results in complications such as joint imbalance, discomfort, and potential need for revision surgeries, as surgeons lack precise methods to achieve balanced joint alignment.

Innovation Solution

A robotic ligament evaluator system with force-torque sensing capabilities and encoders, integrated with a computer-assisted surgery system, allows for precise evaluation and balancing of soft tissues by replicating and guiding joint movements, providing real-time data and adjustments to ensure proper ligament tension and alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual evaluation of soft tissue is used during joint replacement surgery, then the surgeon can perform the procedure, but the precision and reliability of soft tissue balancing is insufficient

Engineering Contradiction:

Improvesoft tissue balancing precisionVSAvoidevaluation system complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical evaluation with an automated robotic system that uses force-torque sensors and encoders to objectively measure ligament tension and joint alignment, eliminating the subjectivity and imprecision of manual assessment

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a robotic intermediary system between the surgeon and the soft tissue evaluation process. This intermediary device performs the measurement and data collection functions, allowing the surgeon to focus on surgical decision-making while obtaining precise objective data

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If automated robotic evaluation is implemented, then measurement precision and reliability improve, but device complexity increases

Engineering Contradiction:

Improvejoint balancing reliabilityVSAvoidrobotic system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The robotic system is designed to perform multiple functions: positioning the joint, applying controlled forces through force-torque sensors, measuring ligament tension, and providing real-time feedback. This multi-functionality consolidates what would otherwise require multiple separate devices into a single integrated system

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The system incorporates real-time feedback through force-torque sensing and encoder measurements, allowing the robotic system to automatically adjust and provide objective data on ligament tension and joint alignment, improving reliability through automated control

Inventive Principle:

Principle #23Feedback

3Manufacturing precision

If manual ligament balancing is performed, then the surgeon has control over the procedure, but manufacturing precision of joint alignment is insufficient

Engineering Contradiction:

Improvejoint alignment precisionVSAvoidsurgical operation ease

Core Design Contradiction:

Manufacturing precisionVSEase of operation

Solution Approach 1:

The patent replaces manual mechanical manipulation with a robotic system that precisely controls joint positioning and force application, enabling consistent and repeatable measurements of ligament tension and joint alignment with higher precision than manual methods

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The robotic system performs self-measurement and self-adjustment through automated force sensing and encoder feedback, eliminating the need for manual trial and error and providing consistent, objective data on joint alignment

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

Enhances surgical precision, reduces post-operative complications, and improves joint performance by ensuring balanced joint alignment through automated ligament balancing, thereby minimizing patient discomfort and the likelihood of subsequent surgeries.

Implementation Method 1

Methodology Applied

Scientific EffectForce-torque sensing:

Implementation Method 2

Methodology Applied

Scientific EffectEncoder measurement:

Data Source

PatentUS20250366780A1Systems and methods for robotic soft tissue evaluation

Publication Date: 2025.12.04 MAKO SURGICAL CORP

AI summary

A method, comprising includes applying, by a robotically-controlled joint positioner, a controlled load to a joint, and, while the controlled load is applied to the joint by the robotically-controlled joint positioner, performing a soft tissue release for the joint and determining a relative displacement between a first bone and a second bone of the joint. The method also includes determining a surgical plan once a desired value for the relative displacement has been achieved by the soft tissue release.