A Compact, Bone-Attached Robot for Mastoidectomy.
Otologic surgery often involves a mastoidectomy, which is the removal of a portion of the mastoid region of the temporal bone, to safely access the middle and inner ear. The surgery is challenging because many critical structures are embedded within the bone, making them difficult to see and requiring a high level of accuracy with the surgical dissection instrument, a high-speed drill. We propose to automate the mastoidectomy portion of the surgery using a compact, bone-attached robot. The system described in this paper is a milling robot with four degrees-of-freedom (DOF) that is fixed to the patient during surgery using a rigid positioning frame screwed into the surface of the bone. The target volume to be removed is manually identified by the surgeon pre-operatively in a computed tomography (CT) scan and converted to a milling path for the robot. The surgeon attaches the robot to the patient in the operating room and monitors the procedure. Several design considerations are discussed in the paper as well as the proposed surgical workflow. The mean targeting error of the system in free space was measured to be 0.5 mm or less at vital structures. Four mastoidectomies were then performed in cadaveric temporal bones, and the error at the edges of the target volume was measured by registering a postoperative computed tomography (CT) to the pre-operative CT. The mean error along the border of the milled cavity was 0.38 mm, and all critical anatomical structures were preserved.
Department of Mechanical Engineering, Vanderbilt University , 2301 Vanderbilt Place , PMB 351592 , Nashville, TN 37235 e-mail:  neal.p.dillon@vanderbilt.edu.
Neal P
NP
Dillon
Department of Otolaryngology, Vanderbilt University Medical Center , 1215 21st Avenue South , MCE 10450 , Nashville, TN 37232 e-mail:  ramya.balachandran@vanderbilt.edu.
Ramya
R
Balachandran
Department of Electrical Engineering and Computer Science, Vanderbilt University , 2301 Vanderbilt Place , PMB 351679 , Nashville, TN 37235 e-mail:  j.michael.fitzpatrick@vanderbilt.edu.
J Michael
JM
Fitzpatrick
Department of Electrical Engineering and Computer Science, Vanderbilt University , 2301 Vanderbilt Place , PMB 351679 , Nashville, TN 37235 e-mail:  michael.a.siebold@vanderbilt.edu.
Michael A
MA
Siebold
Department of Otolaryngology, Vanderbilt University Medical Center , 1215 21st Avenue South , MCE 10450 , Nashville, TN 37232 e-mail:  robert.labadie@vanderbilt.edu.
Robert F
RF
Labadie
Department of Otolaryngology, Vanderbilt University Medical Center , 1215 21st Avenue South , MCE 10450 , Nashville, TN 37232 e-mail:  george.wanna@vanderbilt.edu.
George B
GB
Wanna
Department of Mechanical Engineering, Vanderbilt University , 2301 Vanderbilt Place , PMB 351592 , Nashville, TN 37235 e-mail:  thomas.j.withrow@vanderbilt.edu.
Thomas J
TJ
Withrow
Department of Mechanical Engineering, Vanderbilt University , 2301 Vanderbilt Place , PMB 351592 , Nashville, TN 37235 e-mail:  robert.webster@vanderbilt.edu.
Robert J
RJ
Webster