The Impact of the “Slim-Mesh” Technique on Operation Time and Short/Midterm Outcomes in 67 Overweight, Obese and Superobese Patients from a 10-year Follow-up Study

A multitude of studies have reported dramatically increasing levels of overweight/obesity over the last 20-30 years [1]. These studies not only prove that the number of overweight/obese individuals (Ov/O) is increasing, and is as high as 35% in some countries [1], but that average weight is rising as well. Obesity trends in the USA and the UK project 65 million and 11 million more obese adults respectively by 2030 [2]. Being overweight and obese has long been considered a risk factor for the development of primary and incisional ventral hernias (VH) [3].

Although the pendulum has swung to the laparoscopic intraperitoneal onlay mesh technique (IPOM) due its advantages, a significant number of VH in Ov/O are still carried out with the open technique due to the difficulties and demands of laparoscopy. Open repair of VH can be very challenging with significant associated morbidity and high (up to 50%) [3] incidence of recurrence that require further operations and wasted resources.

mplementing laparoscopic IPOM versus an open approach, and sutureless fixation alternatives versus mesh placement with transfascial sutures [4] have been important aims of research in the last decade. Although studies have shown that obesity is not a controindication to laparoscopic IPOM, the role of minimally invasive surgery in this particular population has not been studied extensively [4]. Many recent reports on the use of laparoscopic IPOM have alluded to its benefits in Ov/O, but no study has specifically investigated its role in obese populations [5].

We thought our Ov/O with VH would benefit from the “Slim-Mesh” [6, 7, 8, 9] approach and we started to study the effect of this technique on them in 2009. Herein, we report the results of our initial study.

At our Department of Surgery, 67 overweight/obese patients (Ov/O) affected by ventral hernia (VH) underwent the “Slim-Mesh” (SM, [6, 7, 8, 9]) procedure from September 2009 to November 2018. For each patient, the demographics, peri-, intra-, and post-operative data were collected prospectively (65% of the cases from September 2016) or retrospectively, after which they were entered into an institutional board-approved Microsoft Excel database. The following variables were included: sex, age, body mass index (BMI), overweight (BMI 25.0–29.9 kg/m²), Class of obesity according to the World Health Organization classification for obesity (Class I BMI 30.0–34.9, Class II 35.0–39.9, Class III 40.0-49.9) [10], and superobesity (SO, using a common definition of SO as massive obesity with a BMI≥50.0–59.9 kg/m²) [11]. We have grouped Class II, III and SO as the “BMI≥35 Group”. The followings variables were also considered: the American Society of Anesthesiologists' (ASA) class, as well as the patients' social and surgical history, VH recurrence, VH type (incisional or primary), time of incisional hernia onset after surgery, preoperative size of fascial defect at physical examination, VH size according to abdominal wall ultrasound (US) and/or CT-scan, VH operative size and type (small/medium (S/M) and large/giant (L/G) according to Korenkov et al's Classification and surgical treatment of incisional hernia [12], massive (M) without loss of domain (≥20 cm), satellite VH, mesh-type (composite or non-composite) used, type of fixation device employed, operative time, estimated blood loss at suction, operative complications, possible conversion to open surgery, early (within 30 days) postoperative complications, readmission to hospital, reoperation, postoperative day when patient returns to regular diet, length of hospital stay, long-term or chronic pain when it lasted >3 months [3], and the final outcome at follow-up (F.U.). Last F.U. February 2020. The results were expressed as a mean±SEM (SD) and as a percentage (%). The operative time was compared among the three groups (overweight patients, Class I obese patients, and “BMI ≥ 35 Group”) using ANOVA. A P<0.05 was considered statistically significant.

This was a single-center non-randomized descriptive study which was approved by Padua's Ethics Committee (contract no. 3902/AO/16) and a written informed consent was obtained from the patients.

Routine follow-up evaluation was performed by interviewing the patients during an outpatients visit, which included a physical examination at 1 and 4 weeks and 3 months postoperatively; patients underwent the same interview, including a review of abdominal wall US results, 6 months after operation, and then yearly.

1. Surgical technique

The 4 surgical phases of our technique have been described in detail previously ([6, 7, 9], Figs. 1, 2, 3, 4, see SM YouTube video). For operations using a small/medium/large (S/M/L) SM, generally we used 3 ports. The Hasson open technique was used for laparoscopic access at the periphery of the abdominal wall, away from the defects and adhesions, after which, the Hasson port was introduced into the abdomen, which was inflated with CO₂ . A 5.5-mm or 12-mm port was then placed under vision in the hypochondriac region and another 5.5-mm port at the iliac fossa.

Fig. 1
“Slim-Mesh” (SM) technique PHASE 1 (see SM YouTube video): First laparoscopic step: (A) Size, location, and total count (3- or 6) for ports for operation using a giant/massive (GM) SM. The first three ports (e.g. No. 1, 2, 3 (Fig.1)), are generally inserted into the abdomen for operation using a small/medium/large SM; for cases of giant (G) SM and for massive (M) SM, an additional 12-mm port (No. 5) for introducing the camera, plus one (No. 4) or two (No. 6) 5.5-mm ports, need to be introduced under vision for the last SM fixation maneuvers at the contralateral periphery of the abdominal wall to the first three abovementioned ports, and several centimeters away from the first edge of the G/M SM to be fixed; (B) Laparoscopic exploration of the whole abdominal cavity with adhesiolysis when necessary, measurement of SM overlap for various sizes of VH according to the SM technique, the marking with methylene blue of 4 peritoneal axial points (West, East, North, and South PAP), and measurement of peritoneal (internal) SM application area (SMAA).

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Fig. 2
PHASE 2: Marking corresponding skin axial points (SAP) and measurement of skin (external) SMAA, which is the same as the peritoneal or internal SMAA.

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Fig. 3
PHASE 3: (A) Tailoring the G SM to the skin (external) SMAA from a prosthesis and marking the 4 axial points (AP) with the first axial point (FAP), in this case the West AP. (B) First rolling-up tightly of the mesh and fixing with a central stitch (CS). (C) Rolling-up the mesh again and fixing with the first set of 2 stitches. (D) Rolling-up the mesh again and fixing with a set of 3 stitches. (E) Rolling-up the G SM and fixing with the second set of 2 stitches. (F) Length of G SM free end (4.5 cm).

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Fig. 4
PHASE 4: Last laparoscopic step: (A) 12-mm port SM introduction with correct FAP position. (B) Intra-abdominal G SM introduction with correct FAP position. (C) SM's FAP (West AP) orienting towards West PAP in this case. (D) Superimposing and fixing FAP onto West PAP with the first absorbable strap (S). (E) Fixing the SM free end with 4 S, creating the first crown, thus preventing the mesh from slipping out of position; the SM is now anchored onto the abdominal wall, after which it no longer needs to be held. (F) SM unrolling, and cutting the second set of 2 stitches. (G) SM unrolling until it reaches the set of 3 stitches. (H) Cutting the set of 3 stitches. (I) SM unrolling again and fixing its South AP onto the South PAP. (J) Fixing the SM North AP onto the North PAP. (K) SM unrolling, and cutting the first set of 2 stitches. (L) SM unrolling and cutting the CS. (M) SM final unrolling and fixing its East AP onto the East PAP. (N) First crown of S. (O) Second crown. (P) Final view of the fixed G SM.

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For operations using a giant/massive (G/M) SM, we use from 3 to 6 ports (Fig. 1A): 3 ports are generally inserted into the abdomen as mentioned above for S/M/L SM; for cases of G SM and for M SM, an additional 12-mm port for introducing the camera, plus one or two 5.5-mm ports, need to be introduced under vision for the last SM fixation maneuvers at the contralateral periphery of the abdominal wall to the first three ports, several centimeters away from the first edge of the G/M SM to be fixed (Fig. 1A). Briefly, we considered 3–5 cm (preferably 5 cm) beyond the edges of the hernia defect to be an adequate SM overlap for small (3–5 cm) [12] VH repair and more than 5 cm for medium (5–10 cm) [12], L/G [12] and M VH repair (during Phase 1, and before the marking of 4 peritoneal axial points (PAP, [6, 7, 9], Figs. 1, 2, 3, 4)), as per Leblanc's advice for larger meshes [13].

Although we normally mark 4 PAP with methylene blue during Phase 1 of the SM operation (Fig. 1B) [6, 7, 8, 9], we ccasionally mark 8 PAP (North, North East, East, South East, South, South West, West, North West) for VH≥10 cm, and these points correspond to the 8 skin axial points in Phase 2. This technical variation might help surgeons during fixation maneuvers of a L/G and M mesh. In the last laparoscopic step, preferably we employed the Ethicon SecureStrap™ Absorbable Fixation Device straps for mesh fixation (Fig. 4).

Sixty-seven patients, 31 overweight/obese (Ov/O) women and 36 Ov/O men, with a mean age in total of 59±1.9 years (mean±SEM; range 31-82 years), underwent “Slim-Mesh” (SM) repair. There were 28 overweight patients, 38 patients classified as obese (BMI ≥ 30), and the remaining case regarded one superobese (SO) patient. BMI was 26.4±0.1 (mean±SEM; range 25-29.9) for the overweight patients; 31.3±0.1 (mean±SEM; range 30–34.9) for the Class I obese patients; and 38.9±0.5 (mean±SEM; range 35–59.9) for the Class II–III obese and SO patients (BMI≥35 Group, Table 1). Table 1 details the demographics, peri- and operative characteristics of the 67 Ov/O patients affected by ventral hernia (VH) who underwent an SM operation.

Table 1
Patient characteristics

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The mean operative time for all of the 67 patients was 100±4.3 minutes (range: 55–240 min., mean±SEM). It was 95±5.3 minutes (range: 55–240 min., mean±SEM) for the overweight patients; 103±3.8 minutes (range: 55–160 min., mean±SEM) for the Class I obese patients; and 103±2.7 minutes (range: 60–150 min., mean±SEM) for the BMI ≥35 Group (P=0.46) (Table 1).

A comparison of the pre-operative and operative VH measurements are reported in Table 2. The internal (laparoscopic) hernia size differed from the external (US and/or CT-scan) hernia size in 28.3% of cases.

Table 2
Comparison between pre- and operative hernia size

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The mean±SEM length of hospital stay was 2.6±0.1 days, and 96% of patients resumed oral intake during the first postoperative day. Early (7th day) postoperative abdominal pain was detected in one female (1.4%). She underwent a second operation with laparoscopy, which revealed the SM to be regularly fixed onto the abdominal wall and no surgical complication was found. The symptom was still present at the third month outpatient visit, and it disappeared spontaneously with the progressive absorption of the straps at the sixth month outpatient visit. We had a single case (1.4%) of chronic postoperative pain.

In February 2020, the last follow-up for mid-term results was carried out, with a minimum of 15 months after surgery.

During a mean±SEM follow-up of 45±3.6 months (range, 15-123 months); all 67 patients received a check-up with routine evaluations according to the above-mentioned surveillance program. Recurrent hernias developed in 3 patients (4.4%): one (1.4%) of which underwent surgery, a small (<2 cm) symptomless recurrence occurred in the remaining 2 cases, in one case after giant VH repair and in the other after massive VH repair. There was two cases of a 12 mm trocar site hernia, which needed surgery.

Overweight and obesity are known risk factors for the development of ventral hernias (VH) [3]. Repairs of this type of hernia in overweight/obese patients (Ov/O) will increase significantly [14], as obesity [15] and the average weight of the world's population are destined to grow over the next 20-30 years [1].

In the past, obesity was considered a major contraindication to laparoscopy [3], as reduced operating space, impaired abdomen visibility and limitations on instruments made it difficult to operate on Ov/O, leading to frequent conversions to laparotomy [3].

However, many recent studies have demonstrated the laparoscopic approach to be superior to open surgery in the obese population undergoing cholecystectomy, appendectomy, segmental colectomy, gastric-banding and bypass [3]. The benefits of laparoscopy are well-known, therefore the “Slim-Mesh” (SM) approach may provide Ov/O with similar advantages.

In the present study, we analyzed the short/midterm outcomes from almost a decade of experience (between September 2009 and December 2018) with 67 Ov/O affected by VH and treated with the new SM technique [6, 7, 8, 9]. We found that patients in obesity Class II (11.9%) and III (2.9%) were young, with mean age of 37 and 41 years respectively; and these Classes are associated with a high incidence of incisional hernias.

In 16.4% of cases, laparoscopy detected additional fascial defects and a mean difference of 4.6 cm between the internal [16] and external measurement of the VH defect (Table 2). This difference was most noticeable in cases of incisional hernia (68.4%, Table 2) and may go unnoticed during open repair [15], as well additional fascial defects. Therefore, we recommend an abdominal-wall study with preoperative US, and/or CT-scan VH combined with laparoscopy [6, 7, 8], especially in Ov/O with incisional VH. Further considerations include the difficulties surgeons face when they carry out physical examinations on Ov/O.

This study confirmed the SM technique's advantageous impact on operation time and intra-postoperative complications [6, 7, 8, 9] also in Ov/O. In fact, mean operative time for overweight patients was 95±5.3 min. (range: 55–240 minutes, mean±SEM); 103±3.8 min. (range: 55–160 minutes, mean±SEM) for Class I obese patients; and 103±2.7 min. (range: 60–150 minutes, mean±SEM) for the “BMI ≥ 35 Group” (Table 1).

In our patients, mean overall operative time was lower (100 minutes) than in Novitsky et al.'s [3] 278 obese patients (178 minutes) and Tsereteli et al.'s [17] 134 obese cases (154 minutes). Both sets of patients underwent laparoscopic ventral hernia repair (LVHR) with transfixation sutures.

In our series, mean operation time for 45 small/ medium, 17 (25.3%) large/giant (L/G) [12], and 5 (7.5%) massive (M) VH was 87±3.1 min. (mean±SEM); 110± 2.6 min. (mean±SEM); and 169±7 min. (mean±SEM) respectively.

The Ethicon SecureStraps™ (Table 1) combined with a sutureless technique such as SM [6, 7, 8, 9] may be a key factor in reducing postoperative chronic pain rates (1.4%) in Ov/O. In the literature, postoperative chronic pain is reported to be high in up to 28% of patients treated with LVHR with transabdominal full-thickness stitches [16].

The use of meshes with a ≥ 5 cm overlap for various sizes of VH, as per the SM technique, could further reduce the recurrence rate. In fact, recurrence occurred in only 3 patients (4.4%); this result is lower than the hernia recurrence rates of Bageacu (17%), Ching et al. [18] (12%), Tsereteli et al. [17] (8.3%) and Novitsky et al. [3] (6%) after LVHR in obese patients, with a mean follow-up time of 49, 19, 19 and 25 months respectively [17, 18].

In our experience the SM technique enables a mesh to be maneuvered more easily [6, 7, 8, 9], then may help in treating Ov/O with L/G and with M VH. The SM approach was beneficial for this group of patients, as it was for normal weight patients suffering from the same types of hernia [6, 7, 8, 9] in terms of decreased intra- postoperative complications, as well as reduced operative time and hospital stays. In fact, the mean length of hospital stay was 2.6± 0.1 days (mean±SEM), which was lower than in Alizai et al.'s [15] 178 overweight/obese patients (5.9 days) and Tsereteli et al.'s [17] 134 obese (BMI>40 Group) cases (3.6 days). Both sets of patients underwent LVHR with transfixation sutures.

A weak point of our study is that our “BMI≥35 Group” (Table 1) comprises only 11 cases. In the future, we will do our utmost to recruit more people with VH from this obese population.

We are aware that in our series duration of mean follow-up time was not very long (45 months; range:15-123 months), however in this period postoperative abdominal-wall chronic pain was detected in the one female (1.4%).

In conclusion, with our study we show that the SM approach may be used safely, even in Ov/O with VH, including L/G (25.3%) and M (7.5%) types, thus avoiding unnecessary laparotomy as in open VH repair and confirming the efficacy of the SM technique.