Load cells for monitoring total knee replacements (TKR)

Published On: August 19 2026

Around 200,000 people in the UK have a knee replacement every year. (5) Whilst total knee arthroplasty (TKA) implants should last for 25 years or more, earlier problems with loosening and imbalance can occur. Detecting these changes is difficult until the problem is fairly acute, which is where load cells come in.

The problem with loosening knees

According to Professor Towfighian of Binghamton University NY,

“We need to solve this issue, because right now there are no sensors inside the implant to show any indication of problems, and then it becomes too late to fix it. The ability to non-invasively measure loads using embedded sensors would enable earlier identification of aberrant loading and the development of treatment strategies.” (1)

Placing a sensor inside the actual replacement knee and accessing the data is one challenge, as is providing power to the load cell itself. So too are the choices of transduction materials used. Researchers suggest the answer to both are energy harvesting-based load sensors that both detect and gather energy from the natural movement of the knee itself. The data could then be read using a mobile phone app.for example.

As a paper in the Journal of Orthopaedic Research explains, research and testing requires an accurate physical model for surgeons and researchers alike to use:

“Total knee arthroplasty (TKA) technique is constantly evolving and the opportunity for surgeons to practice new techniques is currently highly dependent on the availability of cadaveric specimens requiring certified facilities. The high cost, limited supply, and heterogeneity of cadaveric specimens has increased the demand for synthetic training models.”

A working model for all

Research, development and testing of the new generation of synthetic knee models, and testing of the sensor technology itself has been a truly international project.

Much of the sensor research has been conducted using synthetic knee training models devised for surgical training by Australia’s Flinders University Medical Device Research Institute, and built by Australian company Fusetec.
The initial findings were compared with a joint simulator developed at Western University in London, Canada that “simulates the six degrees of freedom in the knee joint.”
Research into creating the self-powered sensor has been also been conducted by a team at Stoney Brook University NY.

This unique collaboration also included:

“The design, development, and testing of a triboelectric nanogenerator (TENG) integrated into an instrumented knee implant for energy harvesting and pressure sensing. The (authors’) unique approach involves utilizing a porous silicone rubber as a dielectric material. This allows the TENG to withstand forces up to 2000 N and generate a maximum power output of 18μW. The proposed TENG shows great potential as a pressure sensor in TKR applications, offering high sensitivity, stability, and low cost.” (3)

Load cells for medical devices

Many medical devices rely on data from load cells, from exoskeletons to robotic surgery devices. For more load cells in medicine stories, see:

A gentle touch: load cells in medical devices

Many medical devices rely on accurately measuring force, enabling adjustments to be made either automatically or manually.

Beyond bruising: investigating how human skin reacts to injury using load cells

Scientists study skin compression and resilience using load cells.

Gently does it: a new smart epidural needle with embedded load cell

This article explores a new epidural needle with a built-in sensor for safer, more precise pain relief during childbirth and surgery.

The power of movement: exoskeletons and load cells

How load cells are helping those with neurological and musculoskeletal movement impairments to move and receive robotic-applied rehabilitation.

Looking for load cells to help with medical device innovation?

About the author

Chris Beasley is Director of Richmond Industries Ltd, designers and manufacturers of advanced load cells and force transducers for industry, governments and universities all over the world.

REFERENCES:

(1) Kocher, C. (2026). Research moves closer to “smart” sensors in knee replacements. Medical Xpress. https://medicalxpress.com/news/2026-04-closer-smart-sensors-knee.html

(2) Flinders University. (2024, May 28). Next-gen knee training model heads for global markets. Medical Xpress. https://medicalxpress.com/news/2024-05-gen-knee-global.html

(3) E. Mahmoudi, A. G. Redgrift, E. Salman, M. Stanacevic, R. Willing and S. Towfighian, “Porous Triboelectric Nanogenerator for Load Sensing of Total Knee Replacement,” in IEEE/ASME Transactions on Mechatronics, vol. 31, no. 3, pp. 3734-3744, June 2026, https://doi.org/10.1109/TMECH.2025.3650092

(4) Bennett KJ, Foroutan P, Fairweather E, et al. Development and validation of a biomechanically fidelic surgical training knee model. J Orthop Res. 2024; 42: 2181-2188. https://doi.org/10.1002/jor.25873

(5) French, J. M. R., Deere, K., Sayers, A., & Whitehouse, M. R. (2025). Trends in hip and knee replacement length of stay and patient demographics in England: a population-based study of 1,455,842 primary procedures. BMC medicine, 23(1), 561. https://doi.org/10.1186/s12916-025-04294-6