Figure 6.

FEA modeling and experiments demonstrate an intermittent AMF exposure can achieve uniform heating across the surface of a prosthetic knee implant. (a) Using COMSOL® a 3D representation of a prosthetic knee implant inside a solenoid coil can be defined. (b) The surface temperature distribution after 3 seconds of continuous 600W AMF exposure is very non-uniform (over 60 °C range across surface). (c) Using an intermittent AMF exposure (1500W for 1 second, every 50 seconds) a uniform surface temperature distribution is achieved after 1200 seconds (20 exposures). The infrared images of the femoral component of a knee prosthesis exposed to AMF (insets of b) and c)) depict the different surface temperature distributions between continuous and intermittent exposures. (d) A prosthetic knee implant was embedded in a phantom composed of bovine bone and muscle-equivalent gel material. (e) Fiber-optic temperature sensors were embedded in the phantom at the locations shown in the schematic. (f) Temperatures recorded over time during an intermittent AMF exposure (300 ms in duration, applied every 15 seconds) demonstrate that after 10 minutes, the top, middle and bottom surfaces were within a few degrees of each other, and were elevated approximately 40 °C above baseline. Further, while the tissue 2mm from the implant is elevated approximately 20 °C above baseline, tissues 22 mm from the implant only experience a temperature elevation of a few degrees C. Movies of the simulations in b) and c) are included as supplemental files.