Experimental Robotic Milling in Skull-Base Surgery

Abstract

OBJECTIVE: In the field of otorhinolaryngology, a variety of skull implants have been developed to assist hearing-impaired or even deaf patients. The first step in the implantation procedure, and also in lateral skull-base surgery, is to drill the calvarian or mastoid bone. We intended to investigate the hitherto unknown parameters for performing this procedure and to establish the first set-up for robotic milling of the lateral skull base. MATERIALS AND METHODS: Experimental milling of the skull base was conducted on two human specimens using a hexapod robot. RESULTS: Optimized parameters were determined with a drill speed of 30,000 revolutions/min and a form feed rate of 5 mm/s for the calvarium and 1 mm/s for mastoid bone, respectively, in a spiral-path fashion. While using a cutting burr, mean force levels were 4.81 N for calvarian bone and 6.12 N for mastoid bone, respectively--well below our empirical limit of 10 N. However, maximum levels easily surpassed these limits, reaching 27.7 N. CONCLUSION: The prerequisites for robotic skull-base surgery were fulfilled. With further work to implement feedback of sensory input, robots may increase precision for various tasks in skull-base surgery.