Koji Morohara; Hidetoshi Katsuno; Tomoyoshi Endo; Kenichi Nakamura; Kazuhiro Matsuo; Kazuki Tsujimura; Tetsuya Koide; Takashi Imanaka; Tomohiro Kubo; Satoshi Arakawa; Tsunekazu Hanai; Zenichi Morise

doi:10.3393/ac.2025.01151.0164

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Original Article Minimally invasive surgery Comparative study of robot-assisted surgery for right-sided colon cancer: a propensity score–matched analysis of the hinotori Surgical Robot System and the da Vinci Surgical System: Koji Morohara¹, Hidetoshi Katsuno¹, Tomoyoshi Endo¹, Kenichi Nakamura¹, Kazuhiro Matsuo¹, Kazuki Tsujimura¹, Tetsuya Koide¹, Takashi Imanaka¹, Tomohiro Kubo¹, Satoshi Arakawa², Tsunekazu Hanai², Zenichi Morise¹; Annals of Coloproctology 2026;42(2):237-246.
DOI: https://doi.org/10.3393/ac.2025.01151.0164
Published online: January 21, 2026

¹Department of Surgery, Fujita Health University Okazaki Medical Center, Okazaki, Japan

²Department of Gastrointestinal Surgery, Fujita Health University Bantane Hospital, Nagoya, Japan

Correspondence to: Koji Morohara, MD, PhD Department of Surgery, Fujita Health University Okazaki Medical Center, 6-1 Harisakinishi 2-chome, Okazaki 444-0829, JapanE Email: koji.morohara@fujita-hu.ac.jp

• Received: September 25, 2025 • Revised: November 12, 2025 • Accepted: November 13, 2025

This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/4.0/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Abstract
INTRODUCTION
METHODS
RESULTS
DISCUSSION
ARTICLE INFORMATION
SUPPLEMENTARY MATERIALS
REFERENCES

Abstract

Purpose
The da Vinci Surgical System has led to major advances in robot-assisted colorectal surgery. Following its patent expiration, domestic alternatives such as the hinotori Surgical Robot System have been developed in Japan. However, clinical comparisons between the hinotori and the da Vinci Xi systems remain limited. This study aimed to compare the short-term outcomes of right-sided colon cancer surgeries performed with either system using propensity score matching.
Methods
This retrospective study included 39 patients who underwent da Vinci–assisted surgery and 37 who underwent surgery using the hinotori system. Propensity score matching was performed using 7 covariates: age, sex, body mass index, American Society of Anesthesiologists physical status, clinical T and N categories, and surgeon experience (≥100 prior robotic colorectal surgeries). To assess the robustness of the findings, inverse probability weighting was also applied using the same covariates. Surgical, postoperative, and pathological outcomes were evaluated.
Results
After matching, 27 patients were included in each group. The hinotori group had significantly longer operative and console times (236 minutes vs. 191 minutes, P=0.001; 140 minutes vs. 90 minutes, P<0.001). No significant differences were observed in blood loss, complication rates, length of hospital stay, or lymph node harvest. No conversions or reoperations occurred. One readmission for ileus was noted in the da Vinci group, whereas none occurred in the hinotori group.
Conclusion
Right colectomy assisted by the hinotori system demonstrated short-term outcomes equivalent to those of the da Vinci system, despite a prolonged operative time. Further prospective studies with larger sample sizes and longer follow-up are warranted.
Keywords: Robotic surgical procedures; Colonic neoplasms; Propensity score–matched analysis; hinotori Surgical Robot System

INTRODUCTION

Robot-assisted surgery (RAS) has gained widespread acceptance in colorectal surgery owing to its enhanced dexterity, tremor suppression, and high-definition 3D visualization [1, 2]. These advantages are particularly valuable in complex procedures that require meticulous dissection, providing clear benefits over conventional laparoscopic surgery. Since the first report of robot-assisted colectomy (RAC) for colon cancer in 2002, numerous studies have confirmed both the feasibility and safety of this approach [3–10]. In addition, recent meta-analyses have described several clinical advantages of RAC, including lower conversion rates, earlier recovery of bowel function, fewer perioperative complications, reduced intraoperative blood loss, and shorter hospital stays [11–14]. In Japan, the inclusion of RAC under national health insurance coverage in April 2022 has further promoted its incorporation into routine clinical practice.

Right colectomy presents considerable anatomical and technical challenges due to the variability of vascular anatomy and the close proximity of major structures such as the superior mesenteric vessels, duodenum, and pancreas. Achieving precise dissection and reliable vascular control in this region requires advanced operative skill and spatial orientation, which may be difficult to achieve with conventional laparoscopic techniques in certain cases. In this context, RAS provides several advantages, including improved instrument articulation, stable camera control, and high-definition 3D visualization, potentially enabling safer and more efficient right-sided colon resections.

Although the da Vinci Surgical System (Intuitive Surgical) has long dominated the field of RAS, the expiration of its core patents in 2019 has facilitated the development of alternative robotic platforms. Among these, the hinotori Surgical Robot System (Medicaroid Corp) became the first domestically developed system approved for gastrointestinal surgery in 2022. As of June 2025, hinotori has been approved for clinical use in Singapore (2023) and Malaysia (2024), with a total of 90 units installed worldwide: 87 in Japan, 1 in Singapore, and 2 in Malaysia. Despite this growing clinical presence, comparative data on the hinotori system remain extremely limited, particularly in colon cancer surgery, where most research continues to focus on the da Vinci system [15–21].

This study aimed to compare short-term surgical outcomes between the hinotori and da Vinci systems in robot-assisted right colectomy using a single-institution, propensity score–matched (PSM) analysis. We hypothesized that the hinotori system would demonstrate surgical performance comparable to that of the da Vinci system in terms of operative time, blood loss, postoperative complications, and pathological outcomes, despite differences in platform configuration and the extent of clinical adoption.

METHODS

Ethics statement

This study was approved by the Institutional Review Board of Fujita Health University (No. HM24-029). Owing to the retrospective design and the use of anonymized data, the requirement for informed consent and consent for publication was waived. All procedures were conducted in accordance with the ethical standards of the Declaration of Helsinki.

Patients

This retrospective study included patients who underwent RAS for right-sided colon cancer using either the da Vinci or the hinotori systems between June 2022 and September 2025. Fujita Health University Okazaki Medical Center, a newly established institution that opened in April 2020, is equipped with both the da Vinci Xi and the hinotori platforms. All procedures in the da Vinci group were performed exclusively with da Vinci Xi. RAC for colon cancer began at the institution in June 2022 using da Vinci Xi, whereas hinotori was introduced in March 2023 following the approval of insurance coverage for gastrointestinal surgical procedures in October 2022.

Patients were assigned to either the hinotori group or the da Vinci group, and comparative analyses were performed for preoperative characteristics, intraoperative parameters, postoperative outcomes, and pathological findings. Intraoperative parameters included total operative time, the interval from skin incision to console start, console time, estimated blood loss, incidence of intraoperative complications, and conversion to open surgery. Postoperative outcomes included length of hospital stay, postoperative complications according to the Clavien-Dindo classification, reoperation rate, and 30-day readmission. Pathological evaluations assessed the number of harvested lymph nodes, resection margin distance, and pathological T and N categories. Preoperative staging was conducted using colonoscopy, barium enema, computed tomography colonography, and contrast-enhanced computed tomography. Tumor staging followed the 9th edition of the Japanese Classification of Colorectal, Appendiceal, and Anal Carcinoma [22]. Patients who underwent emergency surgery or who presented with synchronous malignancies were excluded, as were those with cT4b tumors requiring multivisceral resection. Patients with clinical M1 (stage IV) disease were also excluded from the primary analysis to ensure appropriate comparability between robotic systems.

All procedures were performed or supervised by 2 primary surgeons (HK and KM), each of whom had completed more than 100 robotic surgeries using da Vinci and was certified by the Endoscopic Surgical Skill Qualification System of the Japanese Society for Endoscopic Surgery. When procedures were conducted by less experienced surgeons, either surgeon provided supervisory guidance.

Surgical procedures

All robotic right-sided colectomies were performed using either the da Vinci Xi Surgical System or the hinotori Surgical Robot System. Although the basic configuration and operational workflow of the da Vinci Xi and hinotori systems share several similarities, specific features unique to the hinotori system are outlined below.

The hinotori system consists of 3 major components: an operation unit with 4 robotic arms, a surgeon cockpit, and a monitor cart (Fig. 1). Its design facilitates broad instrument mobility and flexible port placement, which may help reduce excessive tension on surrounding tissues during surgery. The system also incorporates a 3D visualization interface that supports ergonomic operation and may lessen surgeon fatigue during longer procedures. Only features relevant to surgical workflow and patient outcomes were considered in this study [17, 18, 23].

The da Vinci Xi platform is equipped with a table motion function that allows patient repositioning without undocking the robotic arms. This capability is not available in the hinotori system. In the present study, all procedures performed using the da Vinci Xi made use of the table motion function.

Operative technique

In both groups, port placement and surgical approach were identical. All procedures involved bowel mobilization via a retroperitoneal approach and lymph node dissection using the double bipolar technique [17, 24]. The operative technique using the hinotori system is detailed below.

Port placement and instrument configuration for ileocecal resection and right hemicolectomy are shown in Fig. 2, and the distribution of robotic instruments across the 4 arms is illustrated in Fig. 3. Arm 1 was equipped with fenestrated bipolar forceps, and arm 2 carried a 30° endoscope; both remained fixed throughout the procedure. Arm 3 accommodated interchangeable instruments such as monopolar curved scissors or Maryland bipolar forceps, depending on the operative step. Arm 4 was fitted with either Croce grasping forceps or universal grasping forceps, selected according to surgeon preference. The docking-free architecture of the hinotori system provides additional working space around the trocars (Fig. 4).

In general, surgical procedures for right-sided colon cancer began with a mini-laparotomy at the umbilical region. The operation commenced with retroperitoneal mobilization of the right colonic mesentery, followed by lymphadenectomy using the D3 dissection technique and the double bipolar method. During D3 dissection, the surgical trunk was exposed along the left border of the superior mesenteric vein. In ileocecal resection, the ileocolic vessels were transected at their roots (Fig. 5A). In contrast, right hemicolectomy required a broader dissection, including transection of the right branches of the middle colic vessels. The accessory right colic vein was identified at the gastrocolic trunk and ligated during right hemicolectomy (Fig. 5B–D). During retroperitoneal dissection, monopolar curved scissors were frequently used for tissue separation, whereas Maryland bipolar forceps were primarily used for vascular dissection during lymphadenectomy.

After retroperitoneal mobilization and lymph node dissection were completed, the robotic instruments were disengaged and the operation unit withdrawn from the patient. Bowel anastomosis was then performed extracorporeally using a functional end-to-end technique.

Statistical analysis

PSM was conducted to minimize selection bias and improve comparability of baseline characteristics between the da Vinci and hinotori groups. The probability of assignment to each robotic system was estimated using logistic regression incorporating 7 preoperative covariates: age, sex, body mass index (BMI), American Society of Anesthesiologists (ASA) physical status, clinical T category (≤T2 vs. ≥T3), clinical N category (N0 vs. N+), and surgeon experience (≥100 prior robot-assisted colorectal surgeries). Nearest-neighbor matching without replacement was implemented, with the caliper width set at 0.2 of the standard deviation of the logit of the estimated propensity scores. Patients who could not be matched within this caliper were excluded from subsequent analyses.

After matching, covariate balance between groups was assessed using standardized mean differences (SMDs), with values <0.1 indicating excellent balance and <0.2 reflecting acceptable balance. To further evaluate the robustness of the findings, a sensitivity analysis using inverse probability weighting (IPW) was performed based on the same covariates. Stabilized weights were applied in the IPW model, and covariate balance after weighting was also assessed using SMDs. Agreement between PSM and IPW results was interpreted as supporting the validity of the study’s conclusions.

Continuous variables were summarized as medians with interquartile ranges, and categorical variables as counts and percentages. Because most continuous variables were not normally distributed, nonparametric methods were used: the Mann-Whitney U-test for continuous variables and the chi-square test or Fisher exact test for categorical variables, as appropriate. A two-tailed P-value of <0.05 was considered statistically significant. All analyses were performed using EZR ver. 1.68 (Saitama Medical Center, Jichi Medical University), a graphical user interface for R ver. 4.3.1 (R Foundation for Statistical Computing).

RESULTS

Patient characteristics and PSM

A total of 80 patients who underwent robot-assisted right colectomy were initially screened (da Vinci group, n=43; hinotori group, n=37). Four patients in the da Vinci group with clinical stage IV disease were excluded from the comparative analysis, leaving 76 patients eligible for inclusion (da Vinci group, n=39; hinotori group, n=37).

After 1:1 PSM based on age, sex, BMI, ASA physical status, clinical T category (≤T2 vs. ≥T3), clinical N category (N0 vs. N+), and surgeon experience (≥100 prior robot-assisted colorectal surgeries), 27 well-balanced pairs were generated. Before PSM, notable imbalances were present in age (69 years vs. 74 years; SMD, 0.527) and clinical T category (SMD, 0.211). After matching, all covariates achieved acceptable balance (SMD <0.2), confirming appropriate adjustment (Table 1). IPW analysis further improved balance, with most SMDs falling below 0.1, thereby reinforcing the robustness of group comparability (Supplementary Table 1).

Surgical outcomes

As shown in Table 2, operative and console times were significantly longer in the hinotori group than in the da Vinci group (operative time: 236 minutes vs. 191 minutes, P=0.001; console time: 140 minutes vs. 90 minutes, P<0.001). A trend toward a longer interval from skin incision to console activation was also observed in the hinotori group (24 minutes vs. 19 minutes, P=0.058). No significant differences were found between groups in estimated blood loss (19 mL vs. 15 mL, P=0.130), conversion to open surgery, or intraoperative transfusion requirement. The overall complication rate was identical in both groups (7.4%), with 1 case each of surgical site infection and postoperative ileus. No patient required reoperation. The median postoperative hospital stay was 10 days in both groups (P=0.726). One patient in the da Vinci group was readmitted within 30 days due to postoperative ileus.

Pathological findings

Table 3 summarizes the pathological outcomes in the matched cohort. No significant differences were observed in histological grade, lymphatic or vascular invasion, lymph node yield, or resection margins. The median number of harvested lymph nodes was comparable between the da Vinci group and the hinotori group (25 vs. 29, P=0.671). Median proximal and distal margins were 90 mm (da Vinci group) and 100 mm (hinotori group). The distribution of pathological stages was also similar (stage III/IV: 29.6% in the da Vinci group vs. 18.5% in the hinotori group, P=0.526). One case of stage IV disease was identified in the da Vinci group. This patient had been clinically diagnosed with stage III transverse colon cancer but was pathologically reclassified as stage IV due to disseminated nodules in the adjacent greater omentum. Overall, these findings indicate that both robotic systems achieved comparable oncological adequacy in colectomy specimens.

IPW analysis

An additional IPW analysis was conducted to validate the findings from the PSM cohort. Covariate balance was excellent, with most SMDs below 0.1. Although the SMD for age remained slightly above this threshold (0.117), all covariates satisfied the acceptable criterion of SMD <0.2. These results further support the reliability and robustness of the comparative outcomes between the da Vinci and hinotori robotic systems (Supplementary Table 1, Supplementary Fig. 1).

DISCUSSION

RAS has become increasingly prevalent in colorectal surgery owing to its superior dexterity, stable visualization, and enhanced precision compared with conventional laparoscopic techniques. Although the advantages of RAS are well established in rectal surgery, evidence supporting its use in colon surgery (particularly right colectomy) remains relatively limited. In this study, we compared short-term surgical and pathological outcomes between the da Vinci and hinotori robotic systems for robot-assisted right colectomy using a PSM analysis, with IPW applied to further confirm the robustness of the findings.

In this matched comparison, operative and console times were significantly longer in the hinotori group than in the da Vinci group, whereas other perioperative parameters, including blood loss, complication rates, conversion to open surgery, and postoperative hospital stay, were comparable. These findings suggest that, despite prolonged operative duration, the hinotori system can achieve short-term safety and oncological performance equivalent to that of the da Vinci system. This outcome is consistent with previous PSM-based investigations of robot-assisted right colectomy performed using the hinotori platform, which likewise reported similar perioperative and pathological results [20].

Previous studies have reported mean operative times of approximately 200 minutes for robot-assisted right colectomy using the da Vinci system, with variations depending on surgeon experience and institutional volume [10–13]. In the present study, the operative time associated with the hinotori system exceeded this range slightly, which is reasonable for a newly introduced robotic platform during the early phase of clinical adoption. Importantly, intraoperative complication rates and estimated blood loss did not differ significantly between systems, reinforcing the procedural safety of the hinotori system.

The longer operative and console times observed in the hinotori group may reflect system-specific characteristics and the learning curve, although detailed stepwise time analyses were not available. For instance, in contrast to the da Vinci Xi, which permits intraoperative patient repositioning through its table motion function, the hinotori requires manual pivot resetting when adjusting the patient’s position. This additional maneuver may prolong operative time during procedures that necessitate repeated adjustments, such as lymph node dissection or hepatic flexure mobilization. However, as familiarity with pivot control increases, incision-to-console time may shorten. Moreover, increased experience with the docking-free configuration and the multiarm setup of the hinotori system is expected to improve console efficiency.

The comparable lymph node yield and negative resection margins between groups are key indicators of oncological adequacy. Adequate lymph node harvest is a well-recognized prognostic determinant in colon cancer surgery, and our findings suggest that the hinotori system facilitates precise dissection consistent with established oncologic standards. The identical complication rate (7.4%) and equivalent postoperative hospital stay in both groups further confirm that the hinotori provides a safe operative environment. Overall, these results add to the growing body of evidence supporting the feasibility and safety of the hinotori system for colorectal surgery.

To minimize potential bias related to operator proficiency, all procedures in this study were performed or directly supervised by surgeons with more than 100 prior robot-assisted colorectal surgeries. Surgeon assignment was balanced between groups, and surgeon experience was included as a covariate in the PSM model to ensure that operator-related differences had minimal influence on outcome comparisons.

This study has several limitations. First, it was conducted at a single institution with a modest sample size, which may restrict the generalizability of the findings. Second, long-term oncologic outcomes, including disease-free and overall survival, were not assessed. Third, because the hinotori system is still in the early stages of clinical introduction, some parameters, particularly operative time, may have been influenced by the learning curve. Finally, although both PSM and IPW were used to adjust for confounding, unmeasured variables may still have introduced residual bias.

As robotic surgery continues to evolve, the emergence of alternative platforms such as the hinotori may help improve accessibility and cost efficiency in Japan and other Asian countries. The availability of a domestically manufactured robotic system may also stimulate technological innovation and reduce financial barriers associated with robotic procedures, thereby promoting broader adoption of minimally invasive approaches in colorectal surgery. Future multicenter studies with larger patient populations and extended follow-up are warranted to validate these findings and further define the clinical role of the hinotori system.

Conclusions

This single-institution study using PSM demonstrated that the hinotori robotic system achieved short-term surgical and pathological outcomes comparable to those of the da Vinci system in robot-assisted right colectomy. Although operative time was somewhat longer with the hinotori platform, it remained within an acceptable range for a newly introduced robotic system. These findings indicate that hinotori is a feasible and safe option for right colectomy; however, larger multicenter studies with extended follow-up are needed to validate these results and further clarify its clinical role.

ARTICLE INFORMATION

Conflict of interest

No potential conflict of interest relevant to this article was reported.

Funding

None.

Acknowledgments

The authors thank Medicaroid Corporation for providing the photographic images used in this article.

Author contributions

Conceptualization: K Morohara, HK, TH; Investigation: K Morohara, HK, TE, KN, K Matsuo, KT, T Koide, TI, T Kubo, SA; Methodology: K Morohara, HK, SA, TH, ZM; Project administration: K Morohara, HK, ZM; Supervision: HK, TH, ZM; Visualization: K Morohara, HK; Writing–original draft: K Morohara; Writing–review & editing: all authors. All authors read and approved the final manuscript.

SUPPLEMENTARY MATERIALS

Supplementary Table 1.

Covariate balance before and after adjustment

ac-2025-01151-0164-Supplementary-Table-1.pdf

Supplementary Fig. 1.

Covariate balance before and after adjustment using PSM and IPW

ac-2025-01151-0164-Supplementary-Fig-1.pdf

Supplementary materials are available from https://doi.org/10.3393/ac.2025.01151.0164.

Fig. 1.

The hinotori Surgical Robot System (Medicaroid Corp). (A) The operation unit is equipped with 4 robotic arms, each possessing 8 axes to provide greater flexibility in movement. (B) The surgeon cockpit is equipped with a flexibly positioned 3D viewer, designed to reduce neck and shoulder fatigue. (C) Monitor cart. Images courtesy of Medicaroid Corporation.

Fig. 2.

Port placement and instrument configuration for ileocecal resection and right hemicolectomy. (A) Port placement for ileocecal resection and right hemicolectomy. A rigid endoscope was attached to arm 2. (B) Arrangement of the surgical instruments for right hemicolectomy.

Fig. 3.

The 4 robotic arms of the hinotori Surgical Robot System (Medicaroid Corp). (A) Arm 1, fenestrated bipolar forceps in the left hand. (B) Arm 2, rigid 30° endoscope. Arm 3: (C) monopolar curved scissors, (D) bipolar Maryland forceps, and (E) clip applier (medium-large) in the right hand. Arm 4: (F) Croce grasping forceps or (G) universal grasping forceps in the right hand.

Fig. 4.

Fig. 5.

Intraoperative images. (A) Identification of the ileocolic vein root. (B) Identification of the right branch of the middle colic artery. (C) Identification of the gastrocolic trunk and the accessory right colic vein. (D) After lymphadenectomy of the surgical trunk following right hemicolectomy. ICV, ileocolic vein; SMV, superior mesenteric vein; RB-MCA, right branch of the middle colic artery; MCA, middle colic artery; ARCV, accessory right colic vein; GCT, gastrocolic trunk of Henle.

Table 1.

Patient characteristics before and after PSM

Characteristic	Before PSM (n=76)				After PSM (n=54)
Characteristic	da Vinci group (n=39)	hinotori group (n=37)	P-value	SMD	da Vinci group (n=27)	hinotori group (n=27)	P-value	SMD
Age (yr)	69 (32–87)	74 (60–85)	0.069	0.527	73 (55–87)	72 (60–85)	0.924	0.031
Sex			0.647	0.158			>0.999	0.074
Male	18 (46.2)	20 (54.1)			15 (55.6)	14 (51.9)
Female	21 (53.8)	17 (45.9)			12 (44.4)	13 (48.1)
Body mass index (kg/m²)	22.1 (15.6–30.0)	22.6 (15.5–29.9)	0.610	0.069	22.3 (15.6–30.0)	22.5 (15.5–28.4)	0.849	0.095
ASA physical status			>0.999	0.025			>0.999	0.100
I, II	32 (82.1)	30 (81.1)			22 (81.5)	23 (85.2)
III, IV	7 (17.9)	7 (18.9)			5 (18.5)	4 (14.8)
Previous abdominal surgery	14 (35.9)	18 (48.6)	0.353	0.260	9 (33.3)	13 (48.1)	0.406	0.305
Tumor location			0.396	0.331			>0.999	0.083
Cecum	15 (38.5)	11 (29.7)			9 (33.3)	8 (29.6)
Ascending colon	17 (43.6)	22 (59.5)			14 (51.9)	15 (55.6)
Transverse colon	7 (17.9)	4 (10.8)			4 (14.8)	4 (14.8)
Clinical T category			0.491	0.211			>0.999	0.074
Tis, T1, T2	22 (56.4)	17 (45.9)			13 (48.1)	14 (51.9)
T3, T4	17 (43.6)	20 (54.1)			14 (51.9)	13 (48.1)
Clinical N category			0.808	0.093			0.766	0.163
N0	27 (69.2)	24 (64.9)			20 (74.1)	18 (66.7)
N+ (N1, N2, N3)	12 (30.8)	13 (35.1)			7 (25.9)	9 (33.3)
Clinical stage			0.808	0.093			0.766	0.163
0, I, II	27 (69.2)	24 (64.9)			20 (74.1)	18 (66.7)
III	12 (30.8)	13 (35.1)			7 (25.9)	9 (33.3)
Type of procedure			0.484	0.205			0.271	0.381
Ileocecal resection	25 (64.1)	20 (54.1)			18 (66.7)	13 (48.1)
Right hemicolectomy	14 (35.9)	17 (45.9)			9 (33.3)	14 (51.9)
Lymph node dissection			0.487	0.236			>0.999	0.277
D2	0 (0)	1 (2.7)			0 (0)	1 (3.7)
D3	39 (100)	36 (97.3)			27 (100)	26 (96.3)
Surgeon experience^a			>0.999	0.016			0.779	0.154
<100 Cases	14 (35.9)	13 (35.1)			11 (40.7)	9 (33.3)
≥100 Cases	25 (64.1)	24 (64.9)			16 (59.3)	18 (66.7)

Values are presented as median (range) or number (%). da Vinci group, patients who underwent robot-assisted colectomy with the da Vinci Surgical System (Intuitive Surgical). hinotori group, patients who underwent robot-assisted colectomy with the hinotori Surgical Robot System (Medicaroid Corp).

PSM, propensity score matching; SMD, standardized mean difference; ASA, American Society of Anesthesiologists.

^aNumber of robotic colorectal surgeries performed by the surgeon.

Table 2.

Short-term surgical outcomes in propensity score–matched groups

Outcome	da Vinci group (n=27)	hinotori group (n=27)	P-value
Operative time (min)	191 (117–282)	236 (159–367)	0.001^*
Console time (min)	90 (47–162)	140 (75–241)	<0.001^*
Time from incision to console activation (min)	19 (8–60)	24 (12–82)	0.058
Estimated blood loss (mL)	15 (2–104)	19 (6–391)	0.130
Blood infusion	0 (0)	0 (0)	NA
Conversion to laparotomy	0 (0)	0 (0)	NA
Overall complication	2 (7.4)	2 (7.4)	>0.999
Clavien-Dindo classification			>0.999
I	1 (3.7)	0 (0)
II	0 (0)	2 (7.4)
III	1 (3.7)	0 (0)
Postoperative hospital stay (day)	10 (7–45)	10 (7–29)	0.726
Reoperation within 30 days of surgery	0 (0)	0 (0)	NA
Readmission within 30 days of surgery	1 (3.7)	0 (0)	>0.999

NA, not applicable (no events occurred in either group).

*P<0.05.

Table 3.

Pathological findings in propensity score–matched groups

Pathological finding	da Vinci group (n=27)	hinotori group (n=27)	P-value
Histological grade			>0.999
Grade 1–2^a	25 (92.6)	26 (96.3)
Grade 3^b	2 (7.4)	1 (3.7)
Lymphatic invasion	18 (66.7)	12 (44.4)	0.170
Vascular invasion	17 (63.0)	13 (48.1)	0.412
Lymph node retrieval	25 (14–61)	29 (11–67)	0.671
Proximal resection margin (mm)	90 (20–250)	100 (60–280)	0.186
Distal resection margin (mm)	90 (45–160)	100 (40–210)	0.083
Pathological stage			0.526
0, I, II	19 (70.4)	22 (81.5)
III, IV^c	8 (29.6)	5 (18.5)

Values are presented as number (%) or median (range). da Vinci group, patients who underwent robot-assisted colectomy with the da Vinci Surgical System (Intuitive Surgical). hinotori group, patients who underwent robot-assisted colectomy with the hinotori Surgical Robot System (Medicaroid Corp).

^aPapillary or tubular adenocarcinoma (well to moderately differentiated). ^bMucinous or poorly differentiated adenocarcinomas. ^cOne patient in the da Vinci group was found to have pathological stage IV disease postoperatively and was therefore classified as stage III–IV, despite being clinically M0 preoperatively.

REFERENCES

1. Rondelli F, Balzarotti R, Villa F, Guerra A, Avenia N, Mariani E, et al. Is robot-assisted laparoscopic right colectomy more effective than the conventional laparoscopic procedure? A meta-analysis of short-term outcomes. Int J Surg 2015;18:75–82. Article PubMed
2. Yamauchi S, Hanaoka M, Iwata N, Masuda T, Tokunaga M, Kinugasa Y. Robotic-assisted surgery: expanding indication to colon cancer in Japan. J Anus Rectum Colon 2022;6:77–82. Article PubMed PMC
3. Weber PA, Merola S, Wasielewski A, Ballantyne GH. Telerobotic-assisted laparoscopic right and sigmoid colectomies for benign disease. Dis Colon Rectum 2002;45:1689–94. Article PubMed
4. Miller PE, Dao H, Paluvoi N, Bailey M, Margolin D, Shah N, et al. Comparison of 30-day postoperative outcomes after laparoscopic vs robotic colectomy. J Am Coll Surg 2016;223:369–73. Article PubMed
5. Lujan HJ, Plasencia G, Rivera BX, Molano A, Fagenson A, Jane LA, et al. Advantages of robotic right colectomy with intracorporeal anastomosis. Surg Laparosc Endosc Percutan Tech 2018;28:36–41. Article PubMed PMC
6. Scotton G, Contardo T, Zerbinati A, Tosato SM, Orsini C, Morpurgo E. From laparoscopic right colectomy with extracorporeal anastomosis to robot-assisted intracorporeal anastomosis to totally robotic right colectomy for cancer: the evolution of robotic multiquadrant abdominal surgery. J Laparoendosc Adv Surg Tech A 2018;28:1216–22. Article PubMed
7. Schootman M, Hendren S, Loux T, Ratnapradipa K, Eberth JM, Davidson NO. Differences in effectiveness and use of robotic surgery in patients undergoing minimally invasive colectomy. J Gastrointest Surg 2017;21:1296–303. Article PubMed PMC PDF
8. Kulaylat AS, Mirkin KA, Puleo FJ, Hollenbeak CS, Messaris E. Robotic versus standard laparoscopic elective colectomy: where are the benefits? J Surg Res 2018;224:72–8. Article PubMed
9. Blumberg D. Robotic colectomy with intracorporeal anastomosis is feasible with no operative conversions during the learning curve for an experienced laparoscopic surgeon developing a robotics program. J Robot Surg 2019;13:545–55. Article PubMed PDF
10. Park JS, Kang H, Park SY, Kim HJ, Woo IT, Park IK, et al. Long-term oncologic after robotic versus laparoscopic right colectomy: a prospective randomized study. Surg Endosc 2019;33:2975–81. Article PubMed PDF
11. Ma S, Chen Y, Chen Y, Guo T, Yang X, Lu Y, et al. Short-term outcomes of robotic-assisted right colectomy compared with laparoscopic surgery: a systematic review and meta-analysis. Asian J Surg 2019;42:589–98. Article PubMed
12. Solaini L, Bazzocchi F, Cavaliere D, Avanzolini A, Cucchetti A, Ercolani G. Robotic versus laparoscopic right colectomy: an updated systematic review and meta-analysis. Surg Endosc 2018;32:1104–10. Article PubMed PDF
13. Zhu QL, Xu X, Pan ZJ. Comparison of clinical efficacy of robotic right colectomy and laparoscopic right colectomy for right colon tumor: a systematic review and meta-analysis. Medicine (Baltimore) 2021;100:e27002. Article PubMed PMC
14. Solaini L, Bocchino A, Avanzolini A, Annunziata D, Cavaliere D, Ercolani G. Robotic versus laparoscopic left colectomy: a systematic review and meta-analysis. Int J Colorectal Dis 2022;37:1497–507. Article PubMed PMC PDF
15. Miura R, Okuya K, Akizuki E, Miyo M, Noda A, Ishii M, et al. World-first report of low anterior resection for rectal cancer with the hinotori™ surgical robot system: a case report. Surg Case Rep 2023;9:156.Article PubMed PMC PDF
16. Miyo M, Okita K, Okuya K, Ito T, Akizuki E, Ogawa T, et al. Right hemicolectomy for ascending colon cancer using the hinotori surgical robot system: the first ever case report for colon cancer. Asian J Endosc Surg 2023;16:604–7. Article PubMed
17. Katsuno H, Morohara K, Endo T, Chikaishi Y, Kikuchi K, Nakamura K, et al. A new era in surgical oncology: preliminary insights into the hinotori™ surgical robot system's role in rectal surgery using the double bipolar method. World J Surg Oncol 2024;22:215.Article PubMed PMC PDF
18. Morohara K, Katsuno H, Endo T, Kikuchi K, Nakamura K, Matsuo K, et al. Short-term surgical outcomes of robot-assisted colectomy for colon cancer using the hinotori Surgical Robot System. Ann Coloproctol 2025;41:97–103. Article PubMed PMC PDF
19. Tsujimura K, Nakauchi M, Hiro J, Ito A, Chikaishi Y, Kobayashi Y, et al. Comparison of short-term outcomes for robotic rectal surgery between the hinotori™ surgical robot system and da Vinci surgical system: a single-center retrospective study using propensity score matching analysis. Surg Endosc 2025;39:3993–4005. Article PubMed PDF
20. Fujii Y, Asai H, Uehara S, Kato A, Watanabe K, Suzuki T, et al. Feasibility of the hinotori™ surgical robot system in right colectomy: a propensity score matching study. Surg Endosc 2025;39:4006–16. Article PubMed PDF
21. Katsuno H, Morohara K, Endo T, Kikuchi K, Nakamura K, Matsuo K, et al. Propensity score-matched comparison of robot-assisted rectal cancer surgery using hinotori and da Vinci. Ann Coloproctol 2025;41:310–8. Article PubMed PMC PDF
22. Japanese Society for Cancer of the Colon and Rectum. Japanese classification of colorectal, appendiceal, and anal carcinoma: the 3d English edition [secondary publication]. J Anus Rectum Colon 2019;3:175–95. Article PubMed PMC
23. Inoue S, Nakauchi M, Umeki Y, Suzuki K, Serizawa A, Akimoto S, et al. First clinical experiences of robotic gastrectomy for gastric cancer using the hinotori™ surgical robot system. Surg Endosc 2024;38:1626–36. Article PubMed PDF
24. Katsuno H, Hanai T, Endo T, Morise Z, Uyama I. The double bipolar method for robotic total mesorectal excision in patients with rectal cancer. Surg Today 2022;52:978–85. Article PubMed PDF

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Beyond the era of monopoly to diversity: new horizons in robotic colorectal cancer surgery
Jeonghee Han
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Comparative study of robot-assisted surgery for right-sided colon cancer: a propensity score–matched analysis of the hinotori Surgical Robot System and the da Vinci Surgical System

Ann Coloproctol. 2026;42(2):237-246. Published online April 15, 2026

DOI: https://doi.org/10.3393/ac.2025.01151.0164

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Comparative study of robot-assisted surgery for right-sided colon cancer: a propensity score–matched analysis of the hinotori Surgical Robot System and the da Vinci Surgical System

Fig. 1. The hinotori Surgical Robot System (Medicaroid Corp). (A) The operation unit is equipped with 4 robotic arms, each possessing 8 axes to provide greater flexibility in movement. (B) The surgeon cockpit is equipped with a flexibly positioned 3D viewer, designed to reduce neck and shoulder fatigue. (C) Monitor cart. Images courtesy of Medicaroid Corporation.

Fig. 2. Port placement and instrument configuration for ileocecal resection and right hemicolectomy. (A) Port placement for ileocecal resection and right hemicolectomy. A rigid endoscope was attached to arm 2. (B) Arrangement of the surgical instruments for right hemicolectomy.

Fig. 3. The 4 robotic arms of the hinotori Surgical Robot System (Medicaroid Corp). (A) Arm 1, fenestrated bipolar forceps in the left hand. (B) Arm 2, rigid 30° endoscope. Arm 3: (C) monopolar curved scissors, (D) bipolar Maryland forceps, and (E) clip applier (medium-large) in the right hand. Arm 4: (F) Croce grasping forceps or (G) universal grasping forceps in the right hand.

Fig. 4. The 4 robotic arms of the hinotori Surgical Robot System (Medicaroid Corp). (A) Arm 1, fenestrated bipolar forceps in the left hand. (B) Arm 2, rigid 30° endoscope. Arm 3: (C) monopolar curved scissors, (D) bipolar Maryland forceps, and (E) clip applier (medium-large) in the right hand. Arm 4: (F) Croce grasping forceps or (G) universal grasping forceps in the right hand.

Fig. 5. Intraoperative images. (A) Identification of the ileocolic vein root. (B) Identification of the right branch of the middle colic artery. (C) Identification of the gastrocolic trunk and the accessory right colic vein. (D) After lymphadenectomy of the surgical trunk following right hemicolectomy. ICV, ileocolic vein; SMV, superior mesenteric vein; RB-MCA, right branch of the middle colic artery; MCA, middle colic artery; ARCV, accessory right colic vein; GCT, gastrocolic trunk of Henle.

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Comparative study of robot-assisted surgery for right-sided colon cancer: a propensity score–matched analysis of the hinotori Surgical Robot System and the da Vinci Surgical System

Characteristic	Before PSM (n=76)				After PSM (n=54)
Characteristic	da Vinci group (n=39)	hinotori group (n=37)	P-value	SMD	da Vinci group (n=27)	hinotori group (n=27)	P-value	SMD
Age (yr)	69 (32–87)	74 (60–85)	0.069	0.527	73 (55–87)	72 (60–85)	0.924	0.031
Sex			0.647	0.158			>0.999	0.074
Male	18 (46.2)	20 (54.1)			15 (55.6)	14 (51.9)
Female	21 (53.8)	17 (45.9)			12 (44.4)	13 (48.1)
Body mass index (kg/m²)	22.1 (15.6–30.0)	22.6 (15.5–29.9)	0.610	0.069	22.3 (15.6–30.0)	22.5 (15.5–28.4)	0.849	0.095
ASA physical status			>0.999	0.025			>0.999	0.100
I, II	32 (82.1)	30 (81.1)			22 (81.5)	23 (85.2)
III, IV	7 (17.9)	7 (18.9)			5 (18.5)	4 (14.8)
Previous abdominal surgery	14 (35.9)	18 (48.6)	0.353	0.260	9 (33.3)	13 (48.1)	0.406	0.305
Tumor location			0.396	0.331			>0.999	0.083
Cecum	15 (38.5)	11 (29.7)			9 (33.3)	8 (29.6)
Ascending colon	17 (43.6)	22 (59.5)			14 (51.9)	15 (55.6)
Transverse colon	7 (17.9)	4 (10.8)			4 (14.8)	4 (14.8)
Clinical T category			0.491	0.211			>0.999	0.074
Tis, T1, T2	22 (56.4)	17 (45.9)			13 (48.1)	14 (51.9)
T3, T4	17 (43.6)	20 (54.1)			14 (51.9)	13 (48.1)
Clinical N category			0.808	0.093			0.766	0.163
N0	27 (69.2)	24 (64.9)			20 (74.1)	18 (66.7)
N+ (N1, N2, N3)	12 (30.8)	13 (35.1)			7 (25.9)	9 (33.3)
Clinical stage			0.808	0.093			0.766	0.163
0, I, II	27 (69.2)	24 (64.9)			20 (74.1)	18 (66.7)
III	12 (30.8)	13 (35.1)			7 (25.9)	9 (33.3)
Type of procedure			0.484	0.205			0.271	0.381
Ileocecal resection	25 (64.1)	20 (54.1)			18 (66.7)	13 (48.1)
Right hemicolectomy	14 (35.9)	17 (45.9)			9 (33.3)	14 (51.9)
Lymph node dissection			0.487	0.236			>0.999	0.277
D2	0 (0)	1 (2.7)			0 (0)	1 (3.7)
D3	39 (100)	36 (97.3)			27 (100)	26 (96.3)
Surgeon experience^a			>0.999	0.016			0.779	0.154
<100 Cases	14 (35.9)	13 (35.1)			11 (40.7)	9 (33.3)
≥100 Cases	25 (64.1)	24 (64.9)			16 (59.3)	18 (66.7)

Outcome	da Vinci group (n=27)	hinotori group (n=27)	P-value
Operative time (min)	191 (117–282)	236 (159–367)	0.001^*
Console time (min)	90 (47–162)	140 (75–241)	<0.001^*
Time from incision to console activation (min)	19 (8–60)	24 (12–82)	0.058
Estimated blood loss (mL)	15 (2–104)	19 (6–391)	0.130
Blood infusion	0 (0)	0 (0)	NA
Conversion to laparotomy	0 (0)	0 (0)	NA
Overall complication	2 (7.4)	2 (7.4)	>0.999
Clavien-Dindo classification			>0.999
I	1 (3.7)	0 (0)
II	0 (0)	2 (7.4)
III	1 (3.7)	0 (0)
Postoperative hospital stay (day)	10 (7–45)	10 (7–29)	0.726
Reoperation within 30 days of surgery	0 (0)	0 (0)	NA
Readmission within 30 days of surgery	1 (3.7)	0 (0)	>0.999

Pathological finding	da Vinci group (n=27)	hinotori group (n=27)	P-value
Histological grade			>0.999
Grade 1–2^a	25 (92.6)	26 (96.3)
Grade 3^b	2 (7.4)	1 (3.7)
Lymphatic invasion	18 (66.7)	12 (44.4)	0.170
Vascular invasion	17 (63.0)	13 (48.1)	0.412
Lymph node retrieval	25 (14–61)	29 (11–67)	0.671
Proximal resection margin (mm)	90 (20–250)	100 (60–280)	0.186
Distal resection margin (mm)	90 (45–160)	100 (40–210)	0.083
Pathological stage			0.526
0, I, II	19 (70.4)	22 (81.5)
III, IV^c	8 (29.6)	5 (18.5)

Table 1. Patient characteristics before and after PSM

PSM, propensity score matching; SMD, standardized mean difference; ASA, American Society of Anesthesiologists.

^aNumber of robotic colorectal surgeries performed by the surgeon.

Table 2. Short-term surgical outcomes in propensity score–matched groups

NA, not applicable (no events occurred in either group).

*P<0.05.

Table 3. Pathological findings in propensity score–matched groups