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Updated: Aug 7, 2026
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In Vitro Application of a Wireless Sensor in Flexion-Extension Gap Balance of Unicompartmental Knee Arthroplasty
Published on: May 5, 2023
Real-time soft tissue balance assessment in total knee arthroplasty using a wireless flexible sensor array
Mohammad Mansuri Poor1, Mostafa Sohankar1, Aghil Yousefi Koma2
1Center of Advanced Systems & Technologies, School of Mechanical Engineering, University of Tehran, Tehran, Iran.
Medical & Biological Engineering & Computing
|August 6, 2026
Summary
This study introduces a new, affordable flexible sensor system for precisely measuring soft tissue balance during total knee arthroplasty (TKA). The technology offers real-time feedback to improve surgical accuracy and patient outcomes.
Area of Science:
- Biomedical Engineering
- Orthopedic Surgery
- Materials Science
Background:
- Soft tissue balance is critical for successful total knee arthroplasty (TKA), impacting joint stability and implant longevity.
- Current methods for assessing ligament tension during TKA are subjective and error-prone.
- Objective, real-time measurement of soft tissue balance is needed to improve TKA outcomes.
Purpose of the Study:
- To develop and validate a novel, low-cost, and highly sensitive force measurement system for real-time soft tissue balance evaluation during TKA.
- To assess the system's performance in terms of sensitivity, stability, response time, hysteresis, and repeatability.
- To demonstrate the system's potential as an intraoperative tool for optimizing TKA.
Main Methods:
- Fabrication of flexible sensors using RTV silicone rubber filled with carbon nanotubes (CNTs) and carbon black.
- Integration of 24 sensor units into a custom spacer for medial and lateral compartment force measurement.
- Development of a testing platform with data acquisition and a graphical user interface (GUI) for real-time visualization.
Main Results:
- The sensor system demonstrated high sensitivity (0.117 N⁻¹) and stable performance over a 0-100 N range.
- The system exhibited rapid response time (~0.4 s), low hysteresis (~1.18%), and high repeatability (CV < 3%) over 2000 cycles.
- Continuous real-time force measurements were achieved across the full knee motion range (0°, 45°, 90°).
Conclusions:
- The developed flexible sensor system offers a practical, low-cost solution for objective intraoperative assessment of soft tissue balance in TKA.
- This technology has the potential to assist surgeons and robotic systems in achieving optimal soft tissue balance, thereby improving TKA success rates.
- The system's high sensitivity, stability, and repeatability support its use in enhancing TKA procedure precision and patient outcomes.
