Knee Implants Smarten Up
Orthopedic implants keep getting smarter. For the first time, a patient has received an investigational, full artificial knee replacement that can wirelessly report digital, 3D torque and force data back to computers. These advances greatly enhance capabilities compared to the first smart knee implant (implanted on March 9th, 2004). That system reports only knee compressive forces.
The second generation implant provides a wealth of new information: twisting, bending, compressive, and shearing loads across the human kneeall reported dynamically in vivo. The data will provide key inputs for new designs, techniques for implantation, and actual use of knee replacements. Historically, knee implants have been designed using predictions based on theoretical data. With this new technology, the smart total knee replacement can transmit multi-axis loading information directly from patients.
Telemetry has been used to measure forces in hip, spine, and femur but the available space in the knee replacement had previously posed severe barriers. MicroStrain develops wireless microsensors for a wide variety of applications and has focused on making very small wireless strain sensing systems. In fact, the second generation implant handles 12 channels of strain data vs. only four strain channels for the first generation system.