Bone Drilling Sound Monitoring for Orthopedic Surgery Using Wireless Sensor-Embedded Drill-Bit

Abstract

Bone drilling operation is a surgical procedure to prepare screw path for fracture fixation in orthopedic medicine. Drilling has to be operated carefully because over-drilling can make a patient have permanent and severe mechanical damage in important soft tissues. Currently, surgeons perform the operation relying on their feel and experience. They use force/vibration or sound feedback to estimate the current drilling state. However, it is difficult to recognize when drilling has to be stopped in millimeter level because human sensory ability is error-prone. This research proposes a drilling state monitoring method utilizing sound feedback to minimize over-drilling problem. With newly designed wireless sensor-embedded drill-bit, simple sensor installation and collecting good quality of sound signal, which were difficult previously, is realized. In addition, 51 sound features extracted from time, frequency, and wavelet domains and state monitoring algorithm based on artificial neural network are presented. The algorithm achieved more than 98 % of recognition accuracy for four different target states – idle, cortical bone, cancellous bone, and marrow cavity. Finally, two experiments measuring over-drilling depth were conducted for robotic and handheld drilling scenarios, and the results indicated less than 1 mm for robotic drill and 2 mm for handheld drill on average. Compared with approximately 5 mm level for experienced surgeons, improvements were made and the effectiveness was proved. The presented method can be applied to existing systems or operating environments easily and can make efficient operations enabled with precise monitoring ability, regardless of sensory ability or experience level of surgeons. Eventually, the expenses of surgery can be reduced and the safety of patients can be enhanced by minimizing damages from over-drilling and the related complications.