Original Research—Endocrine Surgery

Transaxillary Thyroidectomies: AComparative Learning Experience ofRobotic vs Endoscopic Thyroidectomies

Otolaryngology–Head and Neck Surgery2015, Vol. 152(5) 820–826� American Academy ofOtolaryngology—Head and NeckSurgery Foundation 2015Reprints and permission:sagepub.com/journalsPermissions.navDOI: 10.1177/0194599815573003http://otojournal.org

Kimberley Liqin Kiong, MRCS, MMED1,N. Gopalakrishna Iyer, FRCSEd, PhD2,Thakshayeni Skanthakumar2, Jeremy Chung Fai Ng, FRCSEd3,Ngian Chye Tan, FRCSEd2, Hin Ngan Tay, MMED, FAMS3*, andHiang Khoon Tan, FRCSEd, PhD2*

No sponsorships or competing interests have been disclosed for this article.

Abstract

Objective. Robotic and endoscopic approaches have becomemore accepted in thyroid surgery, with current literaturedocumenting the experience of high-volume centers. Weadopted both approaches concurrently, and this series pre-sents our initial experience to assess the more practicaloption for low- to moderate-volume centers starting outwith transaxillary thyroidectomies.

Study Design. Case series with chart review.

Setting. Tertiary academic center.

Subjects and Methods. Over a period of 4 years, 101 patientsunderwent transaxillary thyroidectomies, of whom 48 under-went robotic thyroidectomy and 53 underwent endoscopicthyroidectomy. Data analysis includes patient characteristics,procedure time, thyroid pathology, and postoperative compli-cations. A survey was conducted among surgeons to assessthe subjective experience.

Results. Endoscopic hemithyroidectomies had a significantlyshorter duration of operation (145.8 minutes) vs that ofrobotic hemithyroidectomies (193.6 minutes), P \ .001. Themean time taken for the first 5 hemithyroidectomies vs thelast 5 hemithyroidectomies showed a greater drop in theendoscopic group (49.1%) vs the robotic group (18.6%).There were 2 cases of transient recurrent laryngeal nerveinjury. In the surgeon survey, the endoscopic technique wasperceived to have less need for peripheral support, whilethe robotic technique was preferred for its shorter learningcurve.

Conclusion. In terms of outcome, both techniques are compara-ble at least in the initial phase. Based on our early experience,the endoscopic technique may be less intuitive with a longerlearning curve, although at steady state, it may be the quickerprocedure. This is relevant for low- to moderate-volume cen-ters starting their transaxillary thyroidectomy program.

Keywords

robotic thyroidectomy, endoscopic thyroidectomy, thyroidsurgery

Received November 12, 2014; revised December 30, 2014; accepted

January 26, 2015.

Since the first endoscopic thyroid lobectomy was per-

formed in 1997,1 many different approaches have been

proposed, convergent on the goals of reduced visible

scars, while balancing improved surgical outcome with ease

of use.2 Initial experience has highlighted technical issues

resulting from inflexible instruments, difficult visualization,

and 2-dimensional images. The da Vinci S surgical robotic

system (Intuitive Surgical, Sunnyvale, California) is a devel-

opment that addresses some of these technical concerns.

Highlights of this system include the stereoscopic view, with

robot arms that mimic the dexterity of human hands.

Multiple studies have been performed to compare the endo-

scopic techniques with open thyroidectomies3-5 and robotic

with open thyroidectomies.6-9 The common thread is that

transaxillary techniques are at least as good as open thyroidec-

tomies. Several recent reports have focused on comparing

robotic with endoscopic thyroidectomies.10-14 Of note, these

studies have been performed in high-volume centers with

inherent biases toward one technique or another. Furthermore,

all these centers had significant experience in endoscopic thyr-

oidectomy before they commenced their robotic thyroidectomy

1SingHealth, Singapore2National Cancer Centre Singapore, SingHealth, Singapore3Singapore General Hospital, SingHealth, Singapore*These authors contributed equally to this article.

Corresponding Author:

Hiang Khoon Tan, FRCSEd, PhD, SingHealth/Duke-NUS Head and Neck

Centre, Academia, Level 5, Singapore General Hospital, 20 College Rd,

Singapore 169856, Singapore.

Email: tan.h.k@nccs.com.sg

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program. At our center, we started our transaxillary robotic

and endoscopic thyroidectomy program at the same time and

collected data prospectively during the initial phase of the pro-

cess. The objective of this study is to present our comparative

experience and the learning process for these 2 techniques.

Our center has a relatively low volume of cases that are eligi-

ble for and interested in transaxillary thyroidectomies. As

such, our learning process and results have shown some differ-

ences from the available literature. We believe our experience

can be valuable and realistic for low- to moderate-volume cen-

ters that are looking to embark on either or both of these tech-

niques without any prior experience.

Patients and Methods

All patients undergoing either robotic (n = 48) or endoscopic

(n = 53) approach thyroidectomy from February 2010 through

August 2014 were included in this study. These represent our

first 101 cases at our institutions. Clinicopathologic, procedure-

related, and outcome data were prospectively recorded. The

study was approved by the SingHealth Centralized Institutional

Review Board (CIRB).

Routine preoperative assessment included a physical exami-

nation, ultrasound scan, and fine-needle aspiration cytology

(FNAC). Inclusion criteria for either of the transaxillary options

were benign nodule up to 5 cm and differentiated thyroid

cancer (DTC) up to 2 cm. Exclusion criteria were previous neck

surgery, evidence of severe thyroiditis, definite extrathyroidal

invasion, and lateral lymph node metastases. These criteria are

similar to those set by Kang et al9 and Lee et al.11 All patients

who satisfied the inclusion/exclusion criteria were then offered

and counseled on the open, transaxillary endoscopic or transaxil-

lary robotic approaches and allowed to choose freely with the

knowledge that the robotic option would cost SGD$7000 more

than either the open or endoscopic approach.

All operations were performed by 5 specialized head and

neck surgeons at the National Cancer Centre Singapore and

Singapore General Hospital. Thyroidectomy extent and man-

agement was based on the American Thyroid Association

(ATA) guidelines.15

Postoperatively, all patients had at least a 6-month follow-up

period. Drain volumes were measured daily until the drains

were removed, when the output decreased to less than 30 mL

over 24 hours. Complications of hematoma, seroma, chyle leak,

and tracheal injury were assessed, while routine calcium and

parathyroid hormone (PTH) levels were measured in patients

undergoing total thyroidectomy. Hypocalcemia was defined as a

corrected serum calcium level \2.1 mmol/L, requiring calcium

replacement, and permanence was defined as replacement

requirements persisting beyond 6 months. Abnormal intact PTH

(iPTH) levels were taken to be \0.9 pmol/L. Any postoperative

hoarseness was assessed by flexible fiber-optic laryngoscopy to

check vocal cord mobility with subsequent follow-up. Transient

recurrent laryngeal nerve (RLN) injury was defined as paresis

lasting less than 6 months.

To assess the subjective experience with each technique,

each surgeon independently completed a 5-question survey.

A sample of the survey is shown in Figure 1. These

questions aim to compare various aspects of the surgical

technique that may lead a surgeon to prefer one technique

over the other.

Operative Methods

Endoscopic thyroidectomy. This technique was done using a

unilateral axillo-breast approach with gas insufflation.

Patients were placed with one arm in full extension and the

neck in slight extension. One incision was made at the apex

of the axilla and another at the ipsilateral areolar junction

for the insertion of 5-mm instrument ports. A further inci-

sion was made midway between these 2 points at the ante-

rior axillary line for the insertion of a 12-mm camera port.

Subsequently, carbon dioxide gas was insufflated to a pres-

sure of 10 to 12 mm Hg to create a working space. Using

suction or a Maryland dissector and L hook instrument, a

flap was created over the pectoralis major muscle and clavi-

cle up to the thyroid notch. Dissection was carried out along

the medial border of the sternocleidomastoid muscle (SCM)

until the superior belly of the omohyoid. This was then dis-

sected to allow upward and lateral retraction. The ster-

nothyroid muscles were split longitudinally to expose the

thyroid lobe. The superior pole was then taken down with

the Harmonic (Johnson & Johnson Medical, Cincinnati,

Ohio) shears. Further capsular dissection was carried out

from the lateral approach with the Harmonic shears. The

RLN and parathyroid glands were identified and preserved.

For a total thyroidectomy, the procedure was repeated on

the contralateral side with similar incisions and approaches

as mentioned above. The specimen was then placed in an

Endopouch (Ethicon, Somerville, New Jersey) and retrieved

via the 12-mm camera port, which was lengthened to a 20-

to 25-mm incision for ease of retrieval when necessary.

Robotic thyroidectomy. Robotic thyroidectomy was carried out

using either gas insufflation or the previously described

Chung’s (gasless) technique.13 In the approach with gas

insufflation, the initial incisions were similar to the endo-

scopic approach. The working space was created with the

endoscopic equipment as described earlier, until the point

where the inner strap muscles were divided longitudinally.

The endoscopic equipment was then removed and an addi-

tional 5-mm incision made in the axilla below the earlier 2

axillary incisions. The robot was then docked with the

camera in the 12-mm port and the Prograsp forceps

(Intuitive Surgical) in the areolar port. Depending on the

Figure 1. Survey on surgeons’ subjective experience.

Kiong et al 821

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side of the lesion, the Maryland forceps and Harmonic

shears were docked on either side of the camera, with the

Harmonic shears operated by the surgeon’s dominant hand.

This is shown in Figure 2, comparing the placement of

incisions and instruments in 2 approaches. The thyroidect-

omy was then performed, again from the lateral approach.

Statistical Analysis

All statistical analysis was performed using SPSS v20.0

software package (SPSS, Inc, an IBM Company, Chicago,

Illinois). Data are expressed as means 6 standard deviation,

proportions, or frequencies. Groups were compared using

the Student t test and the x2 test as appropriate. P values of

\.05 were taken to be statistically significant.

Results

Over the period of the study, there were a total of 1751

thyroidectomies performed at our center, of which 1650

were open thyroidectomies and 101 were conducted with

the transaxillary approach (48 robotic and 53 endoscopic).

Patient demographic data are presented in Table 1. There

was no significant difference between the groups in terms

of these demographic data, except for ages in the robotic

group (42.9 6 12.3 years) and endoscopic group (37.8 6

9.4 years) (P = .025).

Results also showed that both groups were comparable in

terms of pathologic characteristics (Table 1). Mean speci-

men mass was 17.4 6 11.6 g (range, 6-65 g) in the robotic

group and 15.3 6 6.9 g (range, 6-33 g) in the endoscopic

group (P = .315). Mean nodule size was 2.5 6 1.1 cm

(range, 0.6-4.8 cm) for the robotic group and 2.5 6 1.0 cm

(range, 0.6-4.2 cm) for the endoscopic group (P = .954).

There were 12 cases (12.5%) of DTC. The other pathologies

included hyperplasia, goiter, adenoma, cyst, and thyroiditis.

The only 2 patients who required completion thyroidectomy

for DTC had the surgery performed via the same transaxil-

lary approaches.

The operating time was 193.6 6 44.1 (range, 120-305)

minutes for robotic hemithyroidectomies and 145.8 6 50.8

(range, 75-330) minutes for endoscopic hemithyroidec-

tomies (P \ .001). Time of operation was 325.0 6 48.0

(range, 300-390) minutes for robotic total thyroidectomies

and 300 6 26.7 (range, 260-330) minutes for endoscopic

total thyroidectomies (P = .346).

As a surrogate measure of the learning process, we com-

pared the mean duration of operation for the first 5 hemi-

thyroidectomies performed in each group with the mean

time taken for the last 5 hemithyroidectomies (Figure 3).

There was a 49.1% decrease in operating time (230 to 117

minutes) in the endoscopic group compared with an 18.6%

decrease (220 to 179 minutes) in the robotic group.

There was no statistical difference in terms of drain

volumes, pain score, and hospital stay (Table 2). There

were no cases of conversion to an open operation in the

robotic group, while there were 5 (9.4%) cases of conver-

sion in the endoscopic group (P = .029). These were the

3rd, 10th, 15th, 23rd, and 30th cases performed in the endo-

scopic group, in chronological order. Reasons for conver-

sion included inability to visualize the RLN, inability to

separate the thyroid nodule off strap muscles, and bleeding

from a torn thyroid gland.

Postoperative complications for each group are presented

in Table 3. There were 2 (4.2%) cases of transient RLN

injury in the endoscopic group and none in the robotic

group (P = .153). There was 1 case of hematoma in the

endoscopic group (2.1%) and 2 cases in the robotic group

(4.2%). Only 1 case of hematoma required wound explora-

tion, whereby oozing from the pectoralis major muscle was

noted. There was 1 case of brachial plexus injury in the

endoscopic group (2.1%), which recovered spontaneously

within 2 months. There were no other complications such as

seroma, tracheal injury, or chyle leak. Of the 10 total thyroi-

dectomies performed, the robotic and endoscopic groups

each had 2 cases (40%) of transient hypocalcemia (Table4). There were no cases of either permanent hypocalcemia

or permanent RLN injury. Most patients reported some

degree of chest wall numbness postoperatively, but this was

not specifically recorded and analyzed.

Figure 2. Placement of ports in various techniques.

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In terms of the surgeon survey of subjective preference,

results are presented in Table 5. All surgeons preferred the

endoscopic technique in terms of the equipment setup pro-

cess and less need for peripheral support, as well as the

robotic technique for its better ergonomic considerations.

Most (80%) felt that the robotic technique had a shorter

learning curve.

Discussion

The objective of our study is not to perform a conclusive

comparison of the 2 approaches but rather to report on the

comparative early learning experience, having had no prior

experience in any transaxillary approaches.

We used the duration of operation as a surrogate measure

of the ease of operation. The endoscopic technique (145.8

6 50.8 minutes) is noted to have a significantly shorter

duration of operation compared with the robotic technique

(193.6 6 44.1 minutes), where P \ .001. This finding is

mimicked in the study by Lang and Chow,14 contradictory

to the findings in studies conducted in higher volume cen-

ters.11,16 This may be due to the long setup and docking

time required for the robotic technique, which is dependent

on not only the surgeon but also support staff such as the

scrub nurses, who may not be as experienced with the robot

compared with the high-volume centers.10,12 The docking

time represents a significant proportion of the operating

time, especially in the initial stages. Furthermore, some of

these studies focus on DTCs in which tracheoesophageal

groove (TEG) clearance is performed, which is notably dif-

ficult to perform using endoscopic equipment and is there-

fore biased toward the robotic technique.

The difference in time taken to perform total thyroidec-

tomies with each approach was found to be not significant.

This was likely because endoscopic total thyroidectomy

required a bilateral transaxillary approach, whereas in the

robotic total thyroidectomy, lobectomy on the contralateral

side was performed through the same incisions and working

space, thereby cutting down on time required for the setup

and creation of working space. Therefore, it may make

sense to favor the robotic approach in specific cases where

total thyroidectomy or TEG clearance is definitely required.

When comparing the first 5 operations for each technique

performed, there was no significant difference in time of

operation. This could imply that both techniques present an

Table 1. Patient Demographics and Pathologic Characteristics of Specimen and Tumor for the Robotic Group and Endoscopic Group.a

Variable Robotic (n = 48) Endoscopic (n = 48) P Value

Age, y 42.9 6 12.3 (17-66) 37.8 6 9.4 (21-58) .025

Sex .153

Female 46 (95.8) 48 (100)

Male 2 (4.2) 0

Race

Chinese 37 (77.1) 38 (79.2) .718

Malay 4 (8.3) 2 (4.2)

Indian 2 (4.2) 1 (2.1)

Others 5 (10.4) 7 (14.6)

BMI, kg/m2 22.8 6 4.0 (16.2-34.3) 21.6 6 3.2 (16.2-29.3) .125

Indication for operation

Benign 16 (33.3) 17 (35.4) .387

Malignant 4 (8.3) 1 (2.1)

Indeterminate 28 (58.3) 30 (62.5)

Extent of operation

Hemithyroidectomy 43 (89.6) 43 (89.6) 1

Total thyroidectomy 5 (10.4) 5 (10.4)

Specimen mass, g 17.4 6 11.6 (6-65) 15.3 6 6.9 (6-33) .315

Specimen size, cm 5.2 6 2.0 (2.3-14.7) 5.3 6 1.6 (3.5-12) .836

Nodule size, cm 2.5 6 1.1 (0.6-4.8) 2.5 6 1.0 (0.6-4.2) .954

Pathology

Hyperplasia 2 (4.2) 5 (10.4)

Goiter 17 (35.4) 25 (52.1)

Adenoma 16 (33.3) 12 (25)

Cyst 1 (2.1) 3 (6.3)

Thyroiditis 2 (4.2) 1 (2.1)

Follicular carcinoma 1 (2.1) 0

Papillary carcinoma 9 (18.8) 2 (4.2)

aValues are presented as mean 6 SD (range) or number (%).

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equal level of difficulty to a surgeon with absolutely no

prior experience in both. With increase in experience, how-

ever, there is a much larger drop in operating time in the

endoscopic vs robotic technique (49.1% vs 18.6%). Once

again, this finding may be attributable to the setup and

docking of the robot taking a significant proportion of the

total duration of the operation.10,12,17 These reports and our

early experience seem to suggest that endoscopic thyroidect-

omy may be the ‘‘quicker’’ procedure in less experienced

centers. This will have significant impact on the cost analy-

ses of these 2 techniques and should be a subject for future

studies.

In our surgeon survey, 4 of 5 surgeons considered the

robotic technique easier to learn, corroborating the findings

of Lee et al11,16 that the robotic technique seems to have a

shorter learning curve. This may be attributed to the robotic

technique being inherently more intuitive. Our survey

results also showed that our surgeons unanimously preferred

the endoscopic system in terms of equipment setup process

and less technical support required and the robotic technique

for the ergonomic considerations. However, they remained

divided on which technique presented subjective overall

technical ease of use. In the study by Lee et al,18 robotic

thyroidectomy was preferred by surgeons since it was felt to

result in the least musculoskeletal discomfort. We believe

the surgeons’ prior experience and comfort level in other

laparoscopic procedures may influence the choice of their

preferred technique.

Our complication rates are comparable to other studies.

Our transient RLN injury rate at 4.2% is similar to other

larger reported series on open and endoscopic thyroidec-

tomies.13 This is notwithstanding the fact that our center

sees a much smaller volume of cases, and thus the accumu-

lation of surgical experience was at a slower pace. This

bodes well for other centers with a similar caseload that

may want to embark on transaxillary thyroidectomies. In

our study, we presented 5 cases (9.4%) of conversion to

open operation in the endoscopic group. Our foremost con-

sideration during this early stage of our transaxillary thyroi-

dectomy program was patient safety, resulting in a low

threshold to convert cases to open surgery. These cases

occurred early on in the learning curve, showing that this is

less likely to be an issue in the future as we gain more expe-

rience with the procedure. This higher conversion rate com-

pared with the robotic approach is consistent with our

observation that endoscopic thyroidectomy is less intuitive

and may have a longer learning curve.

Over the same time period, a total of 1650 open thyroi-

dectomies were performed at our centers. Although the

number of cases eligible for transaxillary thyroidectomies

was not recorded, transaxillary thyroidectomies represent

5.8% of all thyroidectomies performed. One possible factor

in the selection of approach from the patient’s point of view

may be the cost, as the robotic approach is significantly

more expensive than the conventional open and endoscopic

approaches. This socioeconomic factor may account for the

older mean age of the robotic group. However, this bias

should not affect the surgeons’ perception of these

approaches and the validity of their observations.

Figure 3. Graph comparing mean time taken for first 5 hemithyr-oidectomies vs mean time taken for last 5 hemithyroidectomies ineach group.

Table 2. Outcomes for the Robotic Group and Endoscopic Group.

Variable Robotic (n = 48), Mean 6 SD (Range) Endoscopic (n = 48), Mean 6 SD (Range) P Value

Time of operation, min

Hemithyroidectomy (n = 86) 193.6 6 44.1 (120-305) 145.8 6 50.8 (75-330) \.0001

Total thyroidectomy (n = 10) 325.0 6 48.0 (300-390) 300 6 26.7 (260-330) .346

Drain volume, mL 146.6 6 54.9 (32-255) 145.3 6 101.3 (0-330) .957

Pain score 2.4 6 1.9 (0-5) 3.0 6 1.7 (0-6) .232

Hospital stay, d 3.0 6 0.9 (1-5) 2.6 6 1.2 (1-7) .068

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This study differs from other larger reported series,

mostly from Korea, in 2 key areas. First, Korea has a high

volume of thyroid carcinomas, of which a large proportion

are micropapillary thyroid carcinomas, due to their nation-

wide medical screening programs. Their case profile will

likely differ from cases performed in other parts of the

world.12 Furthermore, most of these centers started perform-

ing the endoscopic technique several years before the

robotic technique and thus would have accumulated much

more prior experience in the transaxillary approach. This

will have a significant impact on their learning curve in

their transition to the robotic technique.16 As we started our

endoscopic and robotic thyroidectomy concurrently, we

have the unique opportunity to compare the challenges of

these 2 techniques at the same phase in the early learning

curve.

We summarize 3 important findings here, especially per-

tinent to low- to moderate-volume centers:

1. Both approaches present a similar initial level of

technical challenge for beginners, as evident from

the similar initial operating time for surgeons with-

out prior experience.

2. Endoscopic thyroidectomies may have a longer

learning curve as the surgery tends to be less intui-

tive, but at steady state, it appears to be a signifi-

cantly shorter procedure since it is less tedious in

terms of the setup process.

3. Both are safe procedures and technically feasible

even for centers with a lower volume of thyroid

cases.

Conclusion

Transaxillary thyroidectomies are a relatively new field in

the long history of thyroid surgery, and one must anticipate

a learning curve. While the robotic technique may have the

advantage of being the more intuitive procedure in the early

stages, the endoscopic technique may be the shorter proce-

dure at steady state, with the added advantage of having a

lower cost and being a less equipment-intensive procedure.

We have shown that despite being on the earlier portion

of the learning curve, the complication rate, including

RLN injury, hypocalcemia, and wound complications, is

low and comparable to open thyroid surgery. Thus, we

believe both these techniques can be performed safely in

low- to moderate-volume centers with the desire to culti-

vate techniques that are more cosmetically appealing.

Ultimately, the cost, patient preference, medical indication,

surgeon comfort, and experience are paramount in the

selection of the appropriate technique for the right patient

by the right surgeon.

Table 3. Postoperative Complications for the Robotic Group andEndoscopic Group.

Variable

Robotic

(n = 48),

No. (%)

Endoscopic

(n = 48),

No. (%) P Value

RLN injury (temporary)

Absent 48 (100) 46 (95.8) .153

Present 0 2 (4.2)

RLN injury (permanent)

Absent 48 (100) 48 (100) NA

Present 0 0

Seroma

Absent 48 (100) 48 (100) NA

Present 0 0

Hematoma

Absent 46 (97.9) 47 (97.9) .558

Present 2 (4.2) 1 (2.1)

Tracheal injury

Absent 48 (100) 48 (100) NA

Present 0 0

Chyle leak

Absent 48 (100) 48 (100) NA

Present 0 0

Brachial plexus injury

Absent 48 (100) 47 (97.9) .558

Present 0 1 (2.1)

Abbreviations: NA, not applicable; RLN, recurrent laryngeal nerve.

Table 4. Postoperative Complications Specific to TotalThyroidectomies.

Variable

Robotic

(n = 5),

No. (%)

Endoscopic

(n = 5),

No. (%) P Value

Hypocalcemia (temporary)

Absent 3 (60) 3 (60) 1

Present 2 (40) 2 (40)

Hypocalcemia (permanent)

Absent 5 (100) 5 (100) NA

Present 0 0

Abbreviation: NA, not applicable.

Table 5. Results of the Surgeon Survey.

Question

Robotic,

No. (%)

Endoscopic,

No. (%)

No Preference,

No. (%)

1. Technical ease of use 1 (20) 2 (40) 2 (40)

2. Equipment setup process 0 5 (100) 0

3. Less support intensive 0 5 (100) 0

4. Ergonomic considerations 5 (100) 0 0

5. Shorter learning curve 4 (80) 1 (20) 0

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Author Contributions

Kimberley Liqin Kiong, study design, data collection and analysis,

drafting of manuscript, approval of final version; N. Gopalakrishna

Iyer, study design, data analysis, revision of manuscript, approval

of final version; Skanthakumar Thakshayeni, data collection,

data analysis, drafting of manuscript, approval of final version;

Jeremy Chung Fai Ng, study conception, revision of manuscript,

approval of final version; Ngian Chye Tan, study design, data

analysis, revision of manuscript, approval of final version; Hin

Ngan Tay, study conception, data analysis, revision of manu-

script, approval of final version; Hiang Khoon Tan, study con-

ception and design, data analysis, revision of manuscript,

approval of final version.

Disclosures

Competing interests: None.

Sponsorships: None.

Funding source: None.

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