22-10-2012, 01:29 PM
Applications of Robotics for Laryngeal Surgery
Robotic Laryngeal Surg concept.pdf (Size: 908.8 KB / Downloads: 33)
The anatomy of the upper airway lends difficulty to the surgical treatment
of laryngeal disease. Open surgery of the larynx allows for increased exposure
of the surgical field and dexterity of instrumentation; however, healthy
tissue, especially the delicate vibratory tissues and framework of the larynx,
may be damaged during the procedure. In contrast, endoscopic laryngeal
surgery uses natural body openings and therefore minimizes resultant damage
to the framework. Even with advancements over the past 30 years,
endoscopic laryngeal surgery continues to have disadvantages, including
the operator’s distance from the surgical field, the laryngoscope’s relatively
small exposure, and reduced depth perception with binocular vision. The
lack of steerable modular instrumentation and three-dimensional (3D) viewing
further handicap the laryngologist’s distal dexterity and suturing ability
[1]. Minimally invasive robotic surgery has the potential to address the
shortcomings of endolaryngeal surgery and to significantly advance laryngeal
surgery.
The human arm represents the greatest actuator known to humans and
represents the basis for which robotic surgical manipulators are constructed.
The human arm is considered to have seven degrees of freedom
provided by three joints. Degrees of freedom (DoF) are often described
using nautical terminology such as pitch (tilting in a vertical vector), yaw
(turning to the left or right), and roll (tilting from side to side). The shoulder
is capable of pitch, yaw, and roll, the elbow pitch, and the wrist pitch,
yaw and roll, totaling seven DoF. The elbow actuator of the human arm
breaks the connection between the shoulder and wrist allowing for roll at
both joints. That differs substantially from an endolaryngeal instrument being
manipulated by a human arm or the da Vinci surgical robot effector
arm. Endolaryngeal instruments are limited by their straight shaft, lack
of a wrist actuator, and the small opening of the laryngoscope. When operated
by the human hand, endolaryngeal instruments have four DoF:
the yaw, pitch, and roll of the human hand and the ability to move in an
out. The degrees of yaw and pitch are limited by the laryngoscope’s opening.
When compared with the human arm, the da Vinci surgical robot has
six DoF. The unique isocenter of motion-proximal actuator allows each robotic
arm to pivot around a point outside of the volume of the actuator.
That is usually at the point of insertion into the human body, which would
be the equivalent of the shoulder in a human arm analogy. However, because
the robotic arm is a straight shaft (lacking the elbow of the human
arm), the roll at the point of skin insertion is the same roll at the endowrist
joint. Therefore, the six DoF of each da Vinci slave manipulator are from
yaw and pitch at the endowrist and skin insertion point, roll along the
shaft, and the ability to move in and out of the port. These six DoF allow
for comparable tissue manipulation to that of the human arm during open
surgical procedures and its application has the potential to greatly advance
laryngeal surgery.