Discussion
There are several advantages of PCS/TAR over other approaches for repair of complex abdominal wall hernias.3 First, it does not require large skin and subcutaneous tissue flaps, which often result in high wound morbidity. Second, since the posterior rectus sheath is closed, a large mesh can be placed as a sublay without concern for contact with the underlying viscera. Other approaches allow only limited options for mesh placement—onlay or underlay. The sublay position used in PCS/TAR, in which native tissue is present on both sides of the mesh, results in the lowest odds of both recurrence and surgical site infections.11
There have been many recent studies evaluating PCS/TAR, but only a few involving specifically emergency general surgery patients and essentially none in trauma patients. In 2013, Carbonell et al reviewed 100 patients with contaminated (58%) and clean-contaminated retrorectus mesh hernia repairs with or without TAR and reported a 7.1% incidence of surgical site infection for clean contaminated cases and 19.0% for contaminated cases, with only seven recurrences, of which four required mesh removal.12 The authors noted that one piece of biologic graft had the same cost as 100 pieces of synthetic mesh. The authors concluded that the surgical dictum that a synthetic mesh is contraindicated in a contaminated field during open abdominal wall reconstructions is not valid.
Krpata et al compared 111 patients who underwent either anterior component separation or PCS.2 Of note, a biologic prosthesis was used in 83.9% of those receiving an anterior component separation and in only 25% of those who received a PCS. There was no difference in the rate of fascial closure between the groups (~91%). The anterior group, however, had more recurrences (14.3% vs. 3.6%) and more wound complications (48.2% vs. 25.4%). It was postulated that the lower wound morbidity was related to the preservation of the abdominal wall blood supply by eliminating the skin and subcutaneous tissue flaps needed for the anterior approach.
In 2014, Lee and colleagues published a systematic review of 32 studies and found that pooled infection rates were 31.6% with biologics and 6.4% with synthetic non-absorbable prosthetics in clean-contaminated cases, with similar hernia rates.13 In contaminated and/or dirty fields, wound infection rates were similar (~40%), but pooled hernia rates were 27.2% with biologics and 3.2% with synthetics. The authors concluded that the available evidence, while limited, does not show the superiority of biologic over synthetic absorbable prosthetics in contaminated fields.
Majumder et al published a multicenter retrospective review in 2016 in which 126 patients underwent major ventral hernia repair in clean-contaminated or contaminated fields.14 Sixty-nine had implantation of a biologic prosthesis and 57 had a synthetic mesh placed. Of the 126 patients, 112 (89%) underwent PCS/TAR. Surgical site infections occurred in 12.3% of the synthetic group and in 31.9% of the biologic group, whereas recurrences occurred in 8.9% of the synthetic group and in 26.3% of the biologic group. The authors concluded that their findings supported the suitability of synthetic mesh and challenged the purported advantage of biologics in contaminated settings.
Also, in 2016, Novitsky et al reviewed a database which included patients from December 2006 to December 2014, in which 428 consecutive patients undergoing PCS/TAR with synthetic mesh were analyzed.15 The mean age was 58, the mean body mass index was 34.4 kg/m2, and the mean hernia defect area was 609 cm2. Of these patients, only 39 (9.1%) developed a surgical site infection, only three patients required mesh debridement, and none required a mesh explant. In addition, of 347 (81%) of those with 1-year follow-up, only 13 (3.7%) had recurrences.
In 2015, Petro et al published an article looking at the use of PCS/TAR in 34 patients with a history of an open abdomen.16 Of these, the fascia was closed in 11, a skin-only closure was done in 4, a split-thickness skin graft was performed in 16, and the wound closed by secondary intention in 3. Of these cases, 21 (61.8%) were contaminated, 7 involved takedown of enterocutaneous fistulas, 4 involved stoma revisions or reversals, and 3 involved excisions of infected mesh. These patients developed 12 surgical site occurrences, 1 dehiscence, 2 hematomas, 1 seroma, and 8 (23.5%) surgical site infections. No patient developed an enterocutaneous fistula or a chronic mesh infection. With a mean follow-up of 18 months, two new parastomal hernias and three midline recurrences have been documented. The authors concluded that the use of PCS/TAR in patients with a history of an open abdomen is associated with low significant perioperative morbidity and recurrence.
In another study, Pauli and colleagues showed that PCS/TAR can address recurrent ventral hernias which developed after initial treatment with anterior component separation.17 The authors noted that anterior component separation treatment of ventral hernias with external oblique release has a recurrence rate of up to 32%. This group reported 29 patients who developed recurrent hernias after anterior component separation, all of which were repaired with PCS/TAR and retromuscular mesh placement and fascial closure. The authors reported 13 (45%) surgical site recurrences, 8 (28%) surgical site infections, and only 1 recurrence, in a patient who developed an organ space infection with frank spillage of stool, requiring mesh excision.
To evaluate the function of the abdominal wall after PCS/TAR with mesh sublay, Criss et al studied 13 patients who agreed to dynamometric analysis both before and 6 months after operation and showed that PCS/TAR was associated with improvement of peak torque, power during isokinetic analysis, and quality of life.18 The authors concluded that restoration of the linea alba by returning the rectus muscles to the midline is associated with improved function of the abdominal wall.
Recently, there has been an emergence of literature about minimally invasive approaches to PCS/TAR.19–22 PCS/TAR has traditionally been performed as an open procedure, but robotic TAR is a novel, minimally invasive technique that combines the benefits of the RSW approach with bilateral TAR with the well-established benefits of minimally invasive surgery. In robotic TAR, pneumoperitoneum is first established with optical access. Then three robotic trocars are inserted laterally under direct visualization. Lysis of adhesions is then performed. The next steps mimic open TAR: the retrorectus plane is developed, the transversus abdominis muscle is divided, and retromuscular dissection is performed. The process is then repeated on the contralateral side. Then the medialized posterior sheaths are reapproximated, and the anterior sheath is closed. The retromuscular pocket that remains is then measured in cranial-caudal and transverse dimensions, and a mesh of appropriate size is placed laparoscopically.
Bittner and colleagues performed a retrospective review of patients who underwent open TAR or robotic TAR from January 2015 to August 2016.20 Of 102 patients, 76 underwent open TAR and 26 had robotic TAR. The robotic TAR group was noted to have a longer operative time (365±78 vs. 287±121 minutes; p<0.01), but the authors note these were the first robotic TARs they had done. The robotic TAR group, however, had a trend toward lower morbidity (19.2% vs. 39.4%; p=0.09), less severe complications, similar low rates of surgical site infections (3.8% vs. 2.6%; p=1.0) and readmissions (7.7% vs. 6.6%; p=1.0), and a shorter median length of hospitalization (3 days (95% CI 3.2 to 4.3) vs. 6 days (95% CI 5.9 to 8.3)).
PCS/TAR with sublay implantation of polypropylene mesh, as demonstrated above, appears to be a durable repair for complex hernias, having a low rate of recurrent herniation and a low rate of surgical site occurrences and infections compared with repairs using a biologic prosthesis. These findings are consistent across multiple studies, as noted above. The concern about infected mesh may be overstated as multiple reports have shown a very low incidence of infected mesh and an even smaller likelihood of the need for mesh explantation. Therefore, even infected mesh may be treated by local debridement of mesh rather than total explant. Of note, PCS/TAR is a difficult repair to perform and there will be a significant learning curve associated with it. This operation may be particularly difficult in patients who have had prior abdominal wall hernia repairs, particularly if mesh had been used. Only sparse literature specifically addresses the use of PCS/TAR in trauma and emergency general surgical patients, so indications for this procedure in these patients will have to be extrapolated from data on unspecified general surgical patients.