Biomechanics of Total Knee Replacements and Energy Harvesting Sensors

Energy Harvesting, Load Sensor: Implant fixation stability is important in the longevity of the implant, and restoration of joint function. However, aseptic loosening, polyethylene bearing wear, and implant misalignment lead to unsatisfactory fixation stability. Currently, there are no commercial devices used for measuring loads postoperatively. By measuring the forces that an implant undergoes postoperatively, signs of implant failure can be quantified so that preemptive measures can be taken to prolong the condition of the knee implant.

An energy harvesting, load sensor is being developed to measure these forces within the knee implant. The energy harvesting, load sensor’s functions are two-fold. Firstly, it is designed to generate its own power through the triboelectric effect. The sensor generates electricity through the cyclic axial compression of metal and polymer layers. Secondly, it is designed to measure loads in the knee implant. The force applied to the sensor is proportional to the magnitude and the frequency of the compressive force applied. So, the self-powered sensor is designed to measure loads as someone performs their everyday tasks.  

3D Printed Augments in Revision Total Knee Replacements: With younger TKR recipients and an aging population, there is a greater need for revision total knee replacements. Implant failure arise from causes such as aseptic loosening and infection. In this study, the fixation stability of a 3D printed augment rTKR was measured with a high resolution camera. The 3D mesh pattern of the Ti6Al4V titanium alloy was designed to achieve several outcomes. These outcomes include improved fixation stability through osseointegration between the bone and the implant and a reduction in stress shielding.

 Comparison between Cruciate Retaining (CR) and Cruciate Sacrificing (CS) TKRs: In severe cases of osteoarthritis (OA), TKA has been an effective method of restoring joint function and relieving joint pain. In this study, the kinematics of CR and CS TKRs were compared with the intact knee. The effects of differing surgical procedures were observed, also. The most conventional method of performing TKR surgery is accessing the joint through the medial side of the patella. On the other hand, accessing the knee laterally reduces damage to surrounding soft tissue during surgery. Overall, different types of TKRs and surgical methods were compared to quantify the effectiveness of restoring joint function.