Resonant frequency of a pin-accelerometer system mounted in bone

Invasive measurements of spinal motion using intraosseous metal pins have become common. For this reason, the resonant frequency of intraosseous pins attached with accelerometers was determined using two different methods. It was concluded that plucking the pin is a reliable method for determining the resonant frequency and, in order to accurately measure bone movement at frequencies up to 32 Hz, the pin diameter should be 2.0 mm or more. With a mass of the accelerometer assembly equal to 27 g, the total pin length should not exceed 80 mm with a bone-accelerometer distance of 25 mm and a pin diameter of 2.4 mm.