Trial Information

A Prospective Randomized Equivalence Trial to Evaluate the Safety of the Ligasure in Thyroid Surgery

Diathermy is an accepted modality to aid surgery and maintain hemostasis and is used in all
forms of surgery including head and neck, neurosurgery and general surgery. The Ligasure
vessel sealing system uses heat energy and has been approved for use in many different types
of surgery and has been tested and accepted for use in multiple countries, including Canada.
What is being tested in this proposal is the application of this accepted technology to
thyroid surgery. There has been one previous randomized trial examining the Ligasure device
in thyroid surgery but this was designed to look at operative times and bleeding episodes in
comparison to manually tying blood vessels. It has been proven that the Ligasure device
makes operations quicker and is just as effective at sealing blood vessels as manual tying
by the surgeon. However, in thyroid surgery injury to the recurrent laryngeal nerve is an
important concern as the nerve is in close proximity to the gland. Damage to the nerve could
temporarily or permanently alter a patient's voice making it hoarse. In this study we
examine if the heat generated by the device could damage the recurrent laryngeal nerve if it
is held close enough for prolonged time periods. There are case reports that indicate that
the Ligasure is safe but this study intends in a prospective, randomized manner to prove
that the use of the Ligasure system does not affect nerve injury rates compared to a surgeon
manually tying blood vessels during thyroid surgery.

Our hypothesis is that the use of the Ligasure vessel sealing system in thyroid surgery is
as safe as the traditional manual tying of blood vessels by the surgeon in terms of injury
to the recurrent laryngeal nerve.

We propose a randomized, prospective equivalence trail to compare recurrent laryngeal nerve
injury rates with the use of the Ligasure device or manually tying blood vessels. The
thyroid gland has two lobes, a left and a right, and under each lobe there is the recurrent
laryngeal nerve (thus two per patient). With the traditional manual tying of vessels,
approximately 2% of patients will have altered function in one of the recurrent laryngeal
nerve, and we expect that the rates of altered function in the Ligasure patient cohort to be
the same. To prove this we will enroll patients with benign thyroid disease, including
multinodular goitre, Grave's disease, thyroid nodule or thyroiditis, having total
thyroidectomy. Excluded are patients under 18 and those with known cancer as well as those
undergoing reoperative surgery or those with known recurrent laryngeal nerve dysfunction.
The patients will be randomized by computer to have dissection of the thyroid gland on one
side (left or right) done with the traditional manual tying method and the other side will
be done with the surgeon using the hand−held Ligasure device. The randomization process uses
a random number generator to assign the patient a number as they are booked for the
operating theatre. This process is independent of the surgeon such that they do not know the
side to use the Ligasure until the day of the operation. After surgery an independent
assessment of the vocal cords with nasopharyngoscopy is done on both the left and right side
within 6 weeks of surgery by an otolaryngologist that is blinded to the surgical technique.
This allows us to determine if either the left or right recurrent laryngeal nerve has been
injured. If there is an injury it will be linked to whether the surgeon manually tied the
vessels on that side or if they used the Ligasure device. Sample size calculations for this
equivalence trial were based on Blackwelder (Controlled Clinical Trials 1982;3:345−353)
which outline that to detect a 5% difference in injury rates, set at 2 in 100, between the
Ligasure and traditional techniques we will need to complete dissections on 96 patients
(each patient has one side Ligasure and one side manual tying).