Knee Joint Distractor with Capacitive Force Sensing

Resolve Bottlenecks,
Find Innovative Solutions
Generate Solutions

Solution Overview

Problem

Orthopaedic surgeons face challenges in accurately balancing joint forces during surgical procedures, particularly in knee replacements, as existing methods rely heavily on manual feel and limited instrumentation, which can lead to inconsistencies and inefficiencies.

Innovation Solution

A system comprising a sensor module with a tibial paddle and handle, equipped with capacitive pressure sensors and a display, provides real-time visual feedback of joint forces through light emitting diodes, allowing surgeons to balance medial and lateral forces effectively.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If manual feel and limited instrumentation are used to balance joint forces, then surgeon experience and manual skill are utilized, but measurement precision and consistency are insufficient

Engineering Contradiction:
Improvejoint force measurement precisionVSAvoidinstrumentation complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces manual mechanical sensing with capacitive pressure sensors that electronically measure joint forces. The sensor array with multiple capacitive elements detects force distribution across the tibial plateau, converting mechanical pressure into electrical signals for precise digital measurement and display.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The surgical instrument integrates force measurement capabilities directly into the tibial paddle structure, allowing the instrument to self-measure the forces it experiences during surgery. The capacitive sensors in the paddle automatically detect and quantify joint forces without requiring separate measurement devices.

Inventive Principle:
Principle #25Self-service

2Manufacturing precision

If real-time visual feedback of joint forces is provided, then surgical accuracy is improved, but device complexity increases due to sensors and display systems

Engineering Contradiction:
Improvesurgical procedure accuracyVSAvoidsensor and display system complexity
Core Design Contradiction:
Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent combines the surgical instrument (tibial paddle) with the measurement and display system into a single integrated device. The capacitive sensors are embedded in the paddle, and the display unit is connected to the same instrument, merging cutting, measurement, and feedback functions into one tool.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The system provides real-time visual feedback through a display unit that shows the magnitude and distribution of joint forces measured by the capacitive sensors. This immediate feedback allows the surgeon to adjust the prosthesis positioning and ligament balancing during surgery to achieve optimal force distribution.

Inventive Principle:
Principle #23Feedback

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

The system enables precise balancing of joint forces, enhancing the accuracy and efficiency of orthopaedic surgical procedures by providing immediate visual feedback, thus improving surgical outcomes.

Implementation Method 1

The sensor array may include a plurality of capacitive pressure sensors configured to generate sensor signals indicative of a force between the patient's tibia and femur

Methodology Applied
Scientific EffectCapacitance: Capacitance

Implementation Method 2

a first display may be secured to an end of the handle. The handle may be secured to the tibial paddle and a first display may be secured to an end of the handle

Methodology Applied
Scientific EffectLight emitting diode: Light Emitting Diode

Data Source

PatentEP3603504B1Distractor to enable the determination of forces of a knee joint
Publication Date: 2022.08.03 DEPUY (IRELAND) LTD
  • EP3603504B1 patent drawingFigure 1
  • EP3603504B1 patent drawingFigure 2
  • EP3603504B1 patent drawingFigure 3~4

AI summary

Ajoint distractor (16) for distracting a patient's knee joint, the distractor comprising: a cradle (500) configured to receive and secure a sensor module, a first distractor (502) component movably coupled to a first side of the cradle, the first distractor component having a first tibial paddle and a first femoral paddle that extend from the first distractor component in an outwardly direction to repetitively contact the tibial paddle of the sensor module and a distal end of a femur of a patient, the first femoral paddle movable with respect to the first tibial paddle to define a first displacement between the patient's tibia and femur, a second distractor (506) component movably coupled to a second side of the cradle, the second distractor component having a second tibial paddle and a second femoral paddle that extend from the second distractor component in the outwardly direction to repetitively contact the tibial paddle of the sensor module and the distal end of a femur of a patient, the second femoral paddle movable with respect to the second tibial paddle to define a second displacement between the patient's tibia and femur, in which the first distractor component and the second distractor component are movable with respect to the cradle in the outwardly direction to permit selectively extending one of the distractor components beyond the other distractor component in the general direction of extension.