Smart Orthopaedic Implants: Applications in Total Knee Arthroplasty

Abstract

Abstract:Total knee arthroplasty is a common orthopaedic procedure conducted in the United States with approximately 700,000 surgeries performed annually. A common complication following total knee arthroplasty is anterior knee pain which affects tens to hundreds of thousands of people each year. The exact mechanism that leads to anterior knee pain remains unknown, but improper component selection may cause pathologic loading of the knee which leads to pain. Measuring loads in the knee to elucidate the mechanisms underlying anterior knee pain remains a challenge because the joints are so small. Using novel wireless sensor technology, we have developed and validated the first "smart" patellar implant capable of measuring force magnitude and force distribution in the knee. Implantable force sensors were calibrated and tested through the range of physiologic loading. Three sensors were then interfaced with a Zimmer patellar implant and placed into a custom loading apparatus. The smart patellar implant was then incrementally loaded from 0-500 N. Sensor signals were all recorded simultaneously in real time to measure the load across the patellofemoral joint. Results demonstrated that the smart patellar implant was able to accurately measure the load being transmitted across the simulated patellofemoral joint.

Smart implants in orthopedic surgery, improving patient outcomes: a review

“…Only recently a smart patellar implant has been developed to measure patellofemoral forces. 40 Three passive resonator force sensors were integrated with an off-the-shelf UHMWPE patellar button with no modification to the implant in a configuration where all forces transmitted through the patellofemoral joint were also transmitted through the sensors. While this technology has yet to be used in vivo, the simple integration of the sensors with the implant makes this technology promising.…”

“…Recently, a family of passive resonator-based sensors has been described that are wireless, battery less, telemetry less and require no electrical connections. 40 , 103 – 105 The small, simple sensors are inexpensive to fabricate (<$1) and can be configured in various sizes and shapes to measure parameters including force, pressure, temperature, pH and specific target analytes. Because of their small size and simplicity, these sensors have the potential to be integrated into off-the-shelf implants will little to no modification of the implant ( Figure 3 ).…”

“Smart Knee Implants: An Overview of Current Technologies and Future Possibilities”

“…Modern knee implants use a polyethylene insert which is sandwiched between the femoral and tibial components (usually metal alloy, alternates being PEEK and ceramic) in theory providing options for inclusion in or attachment to one or more components. In the literature, to date, instrumentation designs have been described for a distal femoral replacement [ 24 ], the tibial tray [ 17 , 25 , 26 ], the polyethylene tibial insert [ 18 , 27 , 28 ], and the patella resurfacing [ 29 ]. The historical timeline of the most advanced smart knee implant prototypes is shown in Fig.…”

“…Instrumentation of the patella button is theoretically also possible. Dion et al described a smart patella design making use of a passive, wireless force sensor [ 29 ]. However, to our knowledge, the use of instrumented patella buttons has not progressed beyond laboratory testing.…”

Bio-compatible wireless inductive thin-film strain sensor for monitoring the growth and strain response of bone in osseointegrated prostheses

“…The compact devices are small in size (largest dimension is 12 mm) and use commercial RFID solutions embedded into glass or ceramic packages. Dion et al 15 propose the use of a capacitive element included in a wireless inductive circuit to measure strain in the implant associated with total knee arthroplasty. The wireless inductor consists of an 11-mm diameter copper coil encased in parylene and embedded directly into the implant.…”