Bone fracture monitoring using implanted antennas in the radius, tibia and phalange heterogeneous bone phantoms

This paper proposes an innovative technique for monitoring the healing of severe bone fractures using a pair of radio frequency monopoles implanted in the fractured bone. It is envisaged that the screws and external fixation used to stabilise and align the bone will also act as monopole antennas. The proposed antenna configurations were measured inside three novel heterogeneous bone phantoms representing the radius, tibia and phalange bones, and the results were compared to computer simulations with a voxel model of a 26-year-old female from CST Microwave Studio's Virtual Family. The power transmitted from one monopole to the other (S-21) was measured and evaluated as an indicator for fracture healing as blood emulating liquid was injected inside the phantom emulating the conditions of a bone fracture. Finally, for the validation of the phantom measurements, an ex-vivo measurement was conducted using a lamb femur bone. In all cases, the power transmitted from one monopole to the other through the fracture decreased significantly as the volume of the blood representing the fracture increased. The proposed system could provide doctors with a quantitative monitoring tool regarding the healing progress of a fractured bone through the reduction of the wound's hematoma during the first four weeks after the trauma that are critical for bone restoration.