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Robotic Versus Laparoscopic Ventral Hernia Repair

One-year Results From a Prospective, Multicenter, Blinded Randomized Controlled Trial

Dhanani, Naila H. MD; Olavarria, Oscar A. MD, MS; Holihan, Julie L. MD, MS; Shah, Shinil K. DO; Wilson, Todd D. MD; Loor, Michele M. MD; Ko, Tien C. MD; Kao, Lillian S. MD, MS; Liang, Mike K. MD

Author Information
doi: 10.1097/SLA.0000000000004795


More than 500,000 ventral hernia repairs are performed each year in the United States with costs exceeding $3 billion annually1 and recurrence rates reported as high as 25%–50% at 5 years.2 There is great need for improvements and advancements based upon evidence at low risk for bias. Robotic surgery has seen tremendous growth in recent years, in part attributable to the rise in cases performed by general surgeons, including ventral hernia repair.3 This growth has been undeterred by the lack of evidence at low risk for bias supporting its use over laparoscopic repair.

We previously published short-term results of a multicenter, blinded, randomized controlled trial (RCT) comparing robotic to laparoscopic ventral hernia repair which demonstrated no differences in postoperative outcomes.4 However, robotic ventral hernia repair was associated with greater operative duration and hospital costs.4 This study presents the clinical and patient-reported outcomes of robotic versus laparoscopic ventral hernia repair at 1-year postoperative.


After institutional review board approval, we performed a multicenter, blinded, RCT comparing robotic to laparoscopic ventral hernia repair. The Consolidated Standards of Reporting Trials (CONSORT) guidelines were followed. The trial was registered on (NCT03490266).5 Primary analysis of early postoperative outcomes was previously published.4 We report 1-year follow-up results in this paper.


Participating centers included Memorial Hermann Hospital System and Lyndon Baines Johnson General Hospital in Houston, Texas.

Selection Criteria

We included adult patients undergoing elective minimally invasive ventral hernia repair with defect less than 12 cm wide, and likely able to tolerate pneumoperitoneum. We excluded patients unlikely to survive more than 2 years, unlikely to follow up, and patients who did not speak either English or Spanish.

Randomization and Blinding

Patients were randomized by computer-generated, variable block in a 1:1 ratio, stratified by surgeon. On the day of surgery, an independent research coordinator randomly assigned patients to the intervention of robotic ventral hernia repair, or the control, laparoscopic ventral hernia repair. Treatment allocation was determined through opening of sequentially numbered, opaque, sealed envelopes. The operating surgeons and research coordinators who determined treatment allocation could not be blinded given the nature of the intervention. However, the patients and post-operative outcome assessors were blinded to the patients’ allocation group.

Intervention and Control

Three high-volume, minimally invasive surgeons participated in this study6 and each performed both robotic and laparoscopic repairs. After institutional review board approval and before the start of the study, each center completed at least 50 standardized repairs as a ramp-up period. No consensus exists on the number of repairs a surgeon should do to establish proficiency or expertise. The literature has reported wide ranges of suggested numbers of cases to achieve a plateau in performance.7,8 Based upon the best available evidence, 50 cases were selected to ensure operating room staff and surgeons were optimized and to mitigate any possible effect of a learning curve of the standardized repair technique used. Patients in this ramp-up period were not included in this trial. However, we reviewed and published our experience to establish a baseline of expertise.9

Ventral hernia repairs were performed using conventional approaches recommended by surgical societies.10,11 Steps common to both robotic and laparoscopic repair are the abdomen was entered in the right or left upper abdominal quadrant with an optical trocar. Pneumoperitoneum was created by insufflating the abdomen with CO2 to an intra-abdominal pressure of 10–15 mm Hg. Two additional trocars were placed under direct visualization. Adhesions were dissected free. Mesh was inserted through a 12-mm port. The hernia defect was closed with 0-polydioxanone. Mid-density, coated polypropylene mesh with at least 5 cm of overlap on all sides relative to the hernia defect was used and secured to the anterior abdominal wall through intraperitoneal onlay technique. The skin was closed with absorbable sutures. Robotic repair was performed using three 8–12 mm ports placed along the lateral abdomen. The platform was docked. Adhesions were taken down with scissors and grasper. The fascial defect was closed with 0-locking, barbed, polydioxanone suture. The mesh was secured intraperitoneally with running 2-0 barbed polydioxanone suture circumferentially, and all 12-mm ports were closed with 0-polyglactin 910 suture. Laparoscopic repair was performed using three 5–12 mm ports. Adhesions were taken down with scissors or vessel sealing device. The fascial defect was closed with 0-polydioxanone sutures. The mesh was secured intraperitoneally with transfascial sutures and a circumferential single or double crown of permanent tacks.


Clinical and patient-reported outcomes were assessed at 1 year postoperatively. Clinical outcomes included wound complication, hernia occurrence, readmission, and reoperation. Wound complication included surgical site infection, defined per the Centers for Disease Control and Prevention,12 and surgical site occurrence which included seroma, hematoma, and wound dehiscence. Hernia occurrence, defined as recurrence or port site hernia, was diagnosed by clinical evaluation by a surgeon blinded to the randomization arm and confirmed by radiographic imaging (computed tomography scan of the abdomen and pelvis). Patient-reported outcomes included functional status, measured using a validated, hernia-specific survey created from the modified Activities Assessment Scale,13 which is a 12-question survey, each question using a 10-point Likert scale. Overall status was calculated by totaling the scores of these 12 questions, then normalizing the score to 100 — 1 indicating poor function and 100 indicating high function. The minimal clinically importance difference (MCID) is 7 for minor change and 14 for major change.14 Additional patient-reported outcomes included pain, using a 10-point visual analog scale with 0 indicating no pain and 10 indicating extreme pain with an MCID of one15; and satisfaction with repair and cosmesis, using a 10-point Likert scale with 0 indicating poor satisfaction and 10 indicating high satisfaction.

Statistical Analysis

Continuous outcomes were analyzed using generalized linear models and binary outcomes were analyzed using logistic modified Poisson regressions adjusting for randomization variable and stratification variable. Among outcomes with no events reported and standard regression could not be completed, Fisher exact test was performed. Patient-reported outcomes at 1-year were adjusted for baseline patient-reported data. Data were analyzed with Stata (version 16.0).


Between April 2018 to February 2019, 124 patients were randomized, 65 to robotic repair and 59 to laparoscopic repair, all of whom proceeded to surgery. Most patients were Hispanic and female, with BMI >30. More patients randomized to the robotic group presented with incisional hernias, while more patients in the laparoscopic group presented with recurrent hernias (Table 1).

TABLE 1 - Baseline Demographics
RVHR (n = 65) LVHR (n = 59)
Age, mean ± SD 50.1 ± 13.3 48.0 ± 12.9
Sex, female 48 (74%) 37 (63%)
 Hispanic 50 (77%) 45 (76%)
 African-American 6 (9%) 9 (15%)
 White 7 (11%) 3 (5%)
 Other 2 (3%) 2 (3%)
Body mass index (BMI), mean ± SD 32.4 ± 4.6 31.8 ± 5.4
Obese, BMI >30 45 (69%) 41 (69%)
Recent smoker 2 (3%) 0
Diabetes mellitus 15 (23%) 12 (20%)
ASA score
 1 5 (8%) 5 (8%)
 2 37 (57%) 37 (63%)
 3 23 (35%) 17 (29%)
 4 0 0
Prior abdominal surgery 57 (88%) 43 (73%)
Hernia type
 Primary 8 (12%) 16 (27%)
 Incisional 57 (88%) 43 (73%)
Recurrent hernia 8 (12%) 15 (25%)
Hernia width, median (IQR) 3.0 (2.0, 5.0) 3.0 (1.0, 4.5)
 Small (<4 cm) 44 (68%) 44 (75%)
 Medium (4–10 cm) 18 (28%) 11 (19%)
 Large (>10 cm) 3 (5%) 4 (7%)
ASA indicates American Society of Anesthesiologists; IQR, interquartile range; LVHR, laparoscopic ventral hernia repair; RVHR, robotic ventral hernia repair; SD, standard deviation.

Sixty patients (92%) in the robotic arm, and 53 patients (90%) in the laparoscopic arm completed follow-up at 1 year (Fig. 1). Median (interquartile range) follow-up time for all patients was 1.0 (1.0, 1.1) year.

Flowsheet of included patients. Reasons for exclusion: declined participation (n = 30), did not clear pre-operative visit (n = 14), surgical plan changed (n = 6), non-English or Spanish speaking (n = 1).

No differences were seen in wound complication rate (15% vs 15%, P = 0.899). Four patients (7%) in the robotic arm suffered hernia recurrence, whereas 5 patients (9%) in the laparoscopic arm suffered recurrence (P = 0.576). No port site hernias were seen in either group (Table 2).

TABLE 2 - Clinical Outcomes
RVHR (n = 60) LVHR (n = 53) P value Relative risk (95% CI)
Follow-up duration, median (IQR) 1.04 (1.00, 1.08) 1.01 (0.99, 1.09) 0.999
Wound complication 9 (15%) 8 (15%) 0.899 0.93 (0.32 to 2.74)
 Surgical site infection 0 1 (2%)
 Surgical site occurrence 9 (15%) 7 (13%)
  Seroma 9 (15%) 6 (11%)
  Hematoma 0 1 (2%)
Hernia recurrence 4 (7%) 5 (9%) 0.576 0.68 (0.17 to 2.68)
Port site hernia 0 0 1.000
Readmission 1 (2%) 3 (6%) 0.251 0.26 (0.03 to 2.61)
Reoperation 0 5 (9%) 0.020
CI indicates confidence interval; IQR, interquartile range; LVHR, laparoscopic ventral hernia repair; RVHR, robotic ventral hernia repair.

There was 1 readmission (2%) in the robotic arm, and 3 (6%) in the laparoscopic arm (P = 0.251). The one readmission in the robotic group was for ileus. In the laparoscopic group, readmissions were due to ileus, abdominal wall abscess, and uncontrolled pain. No reoperations occurred in the robotic arm, whereas 5 (9%) occurred in the laparoscopic arm (P = 0.020). Two patients required seroma excision, one required incision and drainage of abdominal wall abscess, one presented for repair of hernia recurrence, and one underwent diagnostic laparoscopy with removal of tack for chronic pain (Table 2).

Patient-reported outcomes did not differ between groups (Table 3). Both arms reported improved functional status from baseline. Regardless of method, patients had improvement in their median functional status scores above the MCID (e-Table 1, Increase in functional status score was similar between robotic and laparoscopic repair (38.5 vs 45.8, P = 0.254). The difference in pain scores was not statistically significant (P = 0.310). Median satisfaction scores, for both ventral hernia repair and cosmesis, were the highest possible score, 10.0, for both groups.

TABLE 3 - Patient-reported Outcomes. Values are Median (Interquartile Range)
RVHR (n = 60) LVHR (n = 53) P value Mean Difference (95% CI)
Functional status (mAAS) score
 Baseline 48.7 (30.8, 73.4) 45.0 (12.5, 74.3)
 At 1-yr 87.2 (72.0, 95.9) 90.8 (47.3, 96.8) 0.254 4.8 (−3.5 to 13.1)
Pain (VAS) score
 Baseline 3.0 (0.0, 6.0) 3.0 (0.0, 6.0)
 At 1-yr 1.0 (1.0, 5.0) 3.0 (1.0, 7.0) 0.310 −0.7 (−2.1 to 0.7)
Satisfaction score
 VHR satisfaction at 1-yr 10.0 (8.0, 10.0) 10.0 (7.5, 10.0) 0.539 0.3 (−0.7 to 1.3)
 Cosmetic satisfaction at 1-yr 10.0 (5.0, 10.0) 10.0 (6.5, 10.0) 0.738 −0.2 (−1.4 to 1.0)
1 = poor function, 100 = high function.
1 = no pain, 10 = extreme pain.
1 = poor satisfaction, 10 = high satisfaction.LVHR indicates laparoscopic ventral hernia repair; mAAS, modified activities assessment scale; RVHR, robotic ventral hernia repair; VAS visual analog scale; VHR, ventral hernia repair.


Based on this randomized trial, patients have good clinical and patient-reported outcomes after minimally invasive ventral hernia repair, both robotic and laparoscopic. Furthermore, robotic ventral hernia repair may have long-term benefits over laparoscopic repair.

An unexpected finding in our study was more reoperations with laparoscopic repair compared to robotic repair. Although a comparable number of seromas were found between the 2 groups, those in the laparoscopic arm required a higher rate of intervention. This may be due to method of fascial closure or mesh fixation or by chance. In this trial, mesh was fixated using absorbable running suture for robotic repair, and using 4 permanent transfascial sutures with permanent tacks in single or double crown for laparoscopic repair.4 However, with both techniques, the hernia sac, if retained in situ, was included in the closure. Similarly, method of mesh fixation likely contributed to reoperation and tack removal secondary to chronic pain. As this was not our primary outcome, we are unable to conclude if this is a true finding or secondary to chance. These results should be framed in conjunction with our prior RCTs with 2-year reoperation rates following LVHR of 1%–2%.16,17 Given our results and assuming true effect size is 50% lower (4.5% vs 0.5% reoperation rate), 476 patients would be needed for an appropriately powered study to detect a true difference.

Nearly 10% of patients in each arm experienced a recurrence at 1 year. Many of the patients included in this trial were at high risk for recurrence given presence of co-morbidities and prior abdominal surgeries.2 It is unclear if the recurrence rates will taper off and be similar to our other published trials at 24 to 36 months.16,17 The 2-year and 3-year results will shed more light on the timing of recurrence and the overall rate.

Several patients experienced worsened functional status and pain at 1 year when compared to baseline scores (e-Table 1, On further analysis, patients with worsened functional status at 1 year had high median (interquartile range) scores at baseline in both the robotic and laparoscopic arms [83.5 (44.5, 94.0) vs 98.2 (63.3, 100)], potentially signifying little room for improvement for these patients. Similarly, patients with worsened pain at 1 year had a median (interquartile range) baseline pain score of zero [0 (0, 3.0) vs 0 (0, 5.3)]. Although most patients will have clinical benefit with elective hernia repair, for patients with high functional status and/or low pain scores at baseline, repair may have limited or no benefit in improving patient-reported outcomes, but may prevent incarceration or strangulation.

In the short-term, robotic surgery increases operative duration and cost with similar post-operative outcomes compared to laparoscopic surgery.4,18 This is not entirely unexpected as newer technology is often hindered by kinks and users’ initial lack of experience. As surgeons become more experienced and the technology becomes more refined, robotic surgery is expected to at least offer a viable alternative to, if not usurp, laparoscopy. Main limitations of robotic ventral hernia repair are due to increased operative duration and cost. However, many of these studies compare surgeons who have mastery in laparoscopy and who are only novices or proficient at robotic surgery. Our study is one of few trials mandating proficiency with each center performing at least 50 cases of ramp-up. However, proficiency is different from mastery with experience of thousands of laparoscopic cases. With greater experience and mastery, these differences in operative duration could shrink and outcomes may diverge showing benefit. In addition, the cost of new technology is always expensive but with time, growth, and competition, costs can be driven down. Laparoscopy similarly took longer and cost substantially more than open surgery but has usurped much of open procedures.19,20 This study suggests, this is plausible for robotics as well.

There are limitations to this paper. The study was initially powered to detect a 1-day difference in the primary outcome of hospital length of stay at 90-days. Given that this study was not powered to assess differences in recurrence or reoperation, we cannot conclude robotic ventral hernia repair should be routinely offered. This trial included only surgeons who are experts in minimally invasive repair which may limit its generalizability to surgeons with lower volume. Additionally, most defects were small to medium in size, so findings may not be applicable to larger defects. Finally, in this trial we placed mesh intraperitoneal. Although RCTs are lacking comparing optimal repair technique and mesh placement, advocates of robotic repair contend the robot facilitates easier mesh placement in areas other than intraperitoneal (ie, retromuscular repair), which may further improve outcomes.21 Future trials should assess larger defects and different repair techniques.


This study confirms robotic ventral hernia repair is safe when compared to laparoscopic ventral hernia repair. With greater experience, evolving technique, and improved technology the role of robotics may be realized.


This study was possible thanks to Debbie F. Lew and Stephanie Marquez who served as research coordinators. Special thanks to Dr. Henry E. Wang for reviewing and revising this manuscript.


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laparoscopic; patient-centered outcomes; randomized controlled trial; robotic; ventral hernia

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