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Page 8 of 13 Singh et al. Plast Aesthet Res 2020;7:39 I http://dx.doi.org/10.20517/2347-9264.2019.76

As mentioned, HADM has a greater tendency to stretch over time, given the higher relative content of
elastin within the matrix when compared to Porcine versions. Some studies have documented increased
rates of bulging and hernia recurrence in patients with large complex hernias repaired with HADM.
Our group found that, unlike its human analog, PADM resists early stretching after implantation while
still providing comparable tensile strength, thus demonstrating a clinically relevant but statistically non-
[1]
significant benefit to using PADM in abdominal wall reconstruction in the transplant population . Despite
advantages and disadvantages to using either HADM or PADM, at this time, there is little evidence showing
a significant benefit of one type of ADM over another.

Operative approaches
Multiple operative techniques are currently used by general, plastic, and transplant surgeons to repair
incisional hernias in transplant patients. Primary suture repair is often limited to primary ventral hernias
with small defects less than 3 cm. However, some surgeons still opt for mesh reinforcement in small repairs
due to higher rates of recurrence in this patient population. Repair with mesh is recommended for repair
[19]
of incisional hernias larger than 2 cm in a non-infected field . Laparoscopic intraperitoneal onlay mesh
(IPOM) is a commonly-used repair technique for small- to medium-sized hernias, although it has been
[19]
described as useful in facial defects up to 10 cm . IPOM may also be useful in transplant patients who
have undergone multiple abdominal surgeries and either lack a viable peritoneum or are missing a portion
of posterior rectus sheath, thus making them ineligible for retro-rectus repair. In any mesh repair, it is
important to ensure adequate overlap of the defect by at least 3-5 cm to decrease the risk of recurrence
[19]
and to offload tension . Furthermore, recognizing there is a growing adoption of posterior approaches,
there still may be benefit for a modified onlay approach in properly selected patients, as described by the
[20]
authors . In this component separation onlay approach, PADM is anchored to the donor site cut edge
of external oblique on either side of the defect, thus providing a spanning and load-sharing structure that
[20]
reinforces the midline closure with low rate of hernia recurrence and surgical site occurrence .
Open sublay (e.g., retro-rectus) mesh repair has been shown in some studies to have similar recurrence
rates as compared to IPOM, but these sublayed repairs are notable for increased perioperative morbidity
[21]
and hospital length of stay . However, the retro-rectus approach has several advantages when compared
to IPOM and is being used more frequently in incisional hernia repairs in both post-transplant and general
populations. Retro-rectus hernia repair, such as the Rives-Stoppa technique, maintains extraperitoneal
access, which allows the surgeon to avoid contact with intraperitoneal adhesions and other organs,
including the graft. By existing outside of the peritoneum, this technique also prevents the formation of
adhesions that may hinder future surgical interventions, including graft repair and re-transplantation.

Sublay repair is often used in conjunction with component separation techniques in order to restore the
linea alba and medialize the rectus muscles. Component separation in post-transplant patients is often
challenging, as the native planes are often distorted and scarred down. Additionally, as mentioned above,
incisions such as Mercedes incisions have both horizontal and vertical components, which can further
complicate plane dissection and hernia repair. Black et al. described a modified component separation for
[22]
abdominal wall reconstruction in 19 liver and kidney transplant patients, where open perforator-sparing
component separation techniques (e.g., posterior external oblique dissection) were used in conjunction
with biologic mesh underlay. Their data show comparable rates of healing and long-term hernia recurrence
compared to other techniques . More research is needed to examine outcomes and hernia recurrence after
[22]
sublay/retro-rectus repair in transplant patients.

While component separation is often a necessary maneuver to achieve fascial re-approximation, it is
not without potential complications. Anterior component separation (ACS) requires creation of large
subcutaneous flaps, which can disrupt the blood supply via transection of trans-rectus epigastric perforator