An Electroplated Magnetic NiFe Film Based Electromagnetic Targeting for Interlocking-Nail Broken-Bone Surgery

We report a novel interlocking nail onto which magnetic NiFe film is electroplated, for electromagnetic targeting system for screw-hole locating in interlocking-nail broken-bone surgery. The system consists of a C-shaped silicon steel core with emitting and pick-up coils, an intramedullary interlocking nail which the high-permeable magnetic NiFe is electroplated onto two locations of the nail, and measurement electronics. An AC voltage is applied to the emitting coil to generate an AC magnetic flux. Subsequently, by electromagnetic-induction, an AC voltage signal is induced in the pick-up coil. When the electroplated nail is moved axially or rotated in air-gap between the emitting and pick-up coils, the AC magnetic flux between them is affected, resulting in a change in the output voltage of the pick-up coil. This voltage change is further analyzed to determine the location and orientation of the screw holes. Based on this principle, we fabricated above parts and conducted targeting test (also an adhesion/scratching test). According to results, axial and angular targeting errors are 1 mm and 9.5°, respectively. Also, the electroplated film shows an acceptable against-scratching property.