Characteristics of ultrasound device: a new technology for bone curettage and excavation

Background: Ultrasonic (US) devices are used in laparoscopic, dental, and spinal surgeries, while it is difficult to use for the joint under irrigation and perfusion solutions due to lack of power. A new US device is developed with greater voltage improvement and has been implemented in the arthroscopic field. The aim is to compare the characteristics of the US devices with the conventional ones in water. Methods: Twenty bone blocks from the porcine femur were settled in a holder in water. A 4.0 mm diameter abrader burr moved 15 mm along the long axis of the bone block in ten blocks for three times. A 4.3 mm wide curette blade powered by ultrasonic vibration was moved in the same manner in the other ten blocks. The gutter shape, including the gutter depth and the bottom angle of the gutter, and the curetted area ratio of the gutter were assessed. Forty bones blocks from the porcine femurs were clamped with a holder in water, while the cortical bone surface must be located on the side. A 5 mm diameter drill excavated the bone along the previously-inserted guide wire to the 15 mm depth for twenty blocks. Next, the US excavation probe of 5x4mm rectangular shape was moved to the same depth in the other twenty blocks. Each ten block was cut in half along the bone tunnel and was assessed the surface roughness at three area, while the cross-sectional area (CSA) of the tunnel were measured and the ratio of the measured CSA was calculated based on an expected CSA in the remaining ten blocks for each device. Results: The depth of curettage and bottom angle were significantly smaller with the US device than with the abrader burr at all planes, while the curetted area ratio created by each device was mostly equal to the other. Surface roughness was similar in two evacuating devices except one area. CSA ratio with the US excavation device was significantly smaller than that with the drill. Conclusion: US curettage has an advantage to flatly curette bone surfaces, while a bone tunnel can be accurately created with the US device.