A New Robotic Endoscope Holder for Ear and Sinus Surgery with an Integrated Safety Device

Abstract

In the field of sinus and ear surgery, and more generally in microsurgery, the surgeon is faced with several challenges. The operations are traditionally carried out under binocular loupes, which allows for the surgeon to use both hands for a microinstrument and an aspiration tool. More recently, the development of endoscopic otological surgery allowed for seeing areas that are difficult to access. However, the need to handle the endoscope reduces the surgeon's ability to use only one instrument at a time. Thus, despite anaesthesia, patient motions during surgery can be very risky and are not that rare. Because the insertion zone in the middle ear or in the sinus cavity is very small, the mobility of the endoscope is limited to a rotation around a virtual point and a translation for the insertion of the camera. A mechanism with remote center motion (RCM) is a good candidate to achieve this movement and allow for the surgeon to access the ear or sinus. Since only the translational motion along the main insertion axis is enabled, the ejection motion along the same axis is safe for the patient. A specific mechanism allows for inserting and ejecting the endoscope. In a sense, the position is controlled, and the velocity is limited. In the opposite sense, the energy stored in the spring allows for very quick ejection if the patient moves. A prototype robot is presented using these new concepts. Commercially available components are used to enable initial tests to be carried out on synthetic bones to validate the mobility of the robot and its safety functions.

Keywords: RCM; ear; endoscope; parallel robot; safety; sinus; spring energy; surgery.

Figure 1

Comparison of the number of instruments that can be used simultaneously under the microscope and the endoscope. (a) Surgery under a microscope allowing for the use of both hands to operate. (b) Surgery under endoscopy, leaving only one hand for the operator to hold an instrument or suction.

Figure 2

Candidate architecture of the robot with its security, where the numbers represent the names of the rods, and the letters the names of the rotation axes.

Figure 3

Candidate architecture in tilted position, where the numbers represent the names of the rods, and the letters the names of the rotation axes.

Figure 4

Prototype of the robot with an RCM.

Figure 5

CAD modeling of the prototype (a) connection among DC motor, belt, brake, spring, and endoscope and (b) a zoom in on the arrangement of the spring, motor and brake.

Figure 6

Object tracking by visual control.