Hip replacement surgery is quite common among senior citizens of the baby boom generation. But in addition, due to advances in hip implant design and surgical techniques, a growing number of younger patients are undergoing total hip replacement (THR) surgery; however, this procedure can lead to complications and other side effects on the body. Once the implant is placed in the body, it is subject to mechanical loading (contact stress) conditions in a bio-chemical body environment.

Due to such unavoidable in-vivo conditions, it can undergo wear and corrosion. The resulting wear and corrosion produced can cause severe adverse effects on the patient, such as osteolysis and adverse local tissue reactions. The science of the simultaneous wear and corrosion properties of a material in a bio-environment is called, "Bio-Tribocorrosion."

"In order to study the forces and torques acting on a hip joint, we decided to develop a simulator. We needed a system with both force and torque measurement capability which we could easily interface to a PC for ease of data collection. In addition we needed a system that would induce and control the forces and torques we needed to apply to the hip joints via a digital stepper motor. We fortunately found a great solution from Loadstar Sensors that got us 90% of what we needed in a standard solution and the rest we were able to customize with Loadstar's excellent development support" said Dr. Mathew T. Mathew of Rush University Medical Center, located in Chicago, IL.

"Loadstar's RSB3 Load Cell with a Threaded Stud on top and a matching adapter served as a starting point for force measurement. To this we added Loadstar's RST1 Torque Sensor to get both force and torque readings by connecting each to their DI-1000U 24-bit USB Sensor Interface. Then we added a digital stepper motor to the system and used ControlVUE software to both control the motor as well as monitor the sensor outputs in real time" added Dmitry Royhman, a graduate student who worked closely with Dr. Mathew and Loadstar Sensors to develop this system and work out the details.

The developed set-up at Rush University Medical Center, Chicago is a " Tribo-Corrosion Hip Joint Simulator" and is financially supported by the federal agencies NIH and NSF (NIH-R03AR064005, NSF-FDN1160951). We acknowledge the technical support by the Loadstar corporation, USA in constructing this set-up. "This is an example of translational research whereby the knowledge of the loading and bio-chemical conditions in hip implants is tested in order to study the wear and corrosion mechanisms and synergistic interactions of wear and corrosion. The findings are then used to improve hip implant design and possibly lead to better clinical care for orthopedic patients." adds Dr. Mathew.

Loadstar's RSB3 Load Cell with a Threaded Stud on top and a matching adapter served as a starting point for force measurement. To this we added Loadstar's RST1 Torque Sensor to get both force and torque readings by connecting each to their DI-1000U 24-bit USB Sensor Interface. Then we added a digital stepper motor to the system and used ControlVUE software to both control the motor as well as monitor the sensor outputs in real time"

by Dmitry Royhman, a graduate student who worked closely with Dr. Mathew and Loadstar Sensors to develop this system and work out the details