Minimal-invasive ventral mesh rectopexy (VMR) and sacrocolporectopexy (SCR) or
cervicopexy are widely accepted treatments for patients suffering from pelvic prolapse.
Choice of material used in VMR or SCRP - synthetic or biologic surgical mesh - remains
subject of debate. Recent ban in the usage of non abdominal but transvaginal, mesh for
pelvic organ prolapse (POP) in April 2019, by the Food and Drug Administration (FDA) has
negatively influenced the perception on all sorts of surgical mesh. Currently, the most
widely used mesh in VMR is synthetic and has shown good results regarding recurrence,
mesh exposure and functional outcome. Although complication rates are low, the serious
complications of fistulation, exposition, and dyspareunia are reasons to opt for a more
expensive biological mesh. High-quality evidence of synthetic versus biological mesh is
lacking, which does not stop resistance against synthetic mesh from growing. This has
even led to concerns and questions about synthetic mesh use from the Dutch government
addressed at the medical professionals and options for alternatives are being asked.
Biological grafts are characterized by degradation of the implant and regeneration of
host tissue. It is assumed that this process of degradation and remodeling decreases the
risk of exposition and infection. However, this transformation may possibly lead to a
higher chance of recurrence in the long term. Rate of recurrence, but also graft-related
complications (GRC) to a lesser extent, largely depends on duration of follow-up. Since
biological graft implementation in VMR and SCR is relatively new and its usage is
restricted due to higher costs, evidence on biological mesh with long term follow-up is
limited. In addition, there is a significant difference in various described biological
meshes. This is important to keep in mind when comparing outcome of VMR or SCR with
synthetic versus biologic mesh.
In VMR there are no randomised controlled trials on synthetic versus biological mesh. The
biological meshes studied thus far are Biodesign and Permacol. Mesh exposure rates after
VMR with Biodesign and Permacol have both been studied in three studies in total (N = 349
and N = 425 in total respectively) and show low mesh exposure rates of 0 to 0.1%. In
comparison, GRC after VMR with synthetic non-resorbable mesh (like polypropylene) are
around 2%. Recurrence rates after synthetic mesh in VMR range between 2% and 14% after a
median follow-up of 12-61 months. When comparing studies on biologic implants that report
on recurrence rates there seems to be a slight difference in favor of Biodesign. Studies
on Biodesign in VMR with a median follow-up ranging between 12 and 47 months show a
recurrence rate around 5%. Literature on Permacol shows higher recurrence rates ranging
between 5 to 14% after a median follow-up of 12 to 29 months.
In sacrocolpopexy (SCP) allografts and xenografts have been investigated as an
alternative for polypropylene. A randomised controlled trial compared SCP using
polypropylene mesh with solvent cadaveric fascia lata. After one year of follow-up,
polypropylene mesh had a higher anatomical cure rate than cadaveric fascia lata (91
percent versus 68 percent; p=0.007). Two GRC occurred in patients who received
polypropylene mesh, while none occurred in the allograft group (p= 0.5). Another RCT with
the same comparison and a follow-up of 5 years showed similar results, with considering
cadaveric fascia not as strong of a support. Deprest et al. compared polypropylene mesh
with porcine grafts in a prospective study and found xenografts to be associated with
more apical failures and reoperations than with a polypropylene mesh (21 percent versus 3
percent; p = 0.01).However, there was no significant difference in functional outcomes
between the two groups. An exposure rate of 11 percent was described in both groups. A
more recent study concluded, by analyzing clinical outcomes and patients satisfaction,
that a non-crosslinked ADM patch can be a good alternative to synthetic polypropylene
mesh in patients undergoing SCP.
Although Biodesign (Surgisis), Permacol and other are all grouped under the common
denominator 'Biologic mesh', each of these products is unique. There are differences in
tissue source, differences in the processes used to decellularize the tissue and
differences in the final processing steps such as sterilization and preservation. As a
result, there are significant variations in biological and clinical performance between
these products. Permacol, which is purposely cross-linked pig dermis, behaves like a
synthetic material in-vivo and induces a permanent foreign body response, leading to
encapsulation. This prevents integration with and in the surrounding tissue.
Consequently, high rates of mesh exposure occur with Permacol implants. Biodesign, one of
the early biologics, is derived from small intestinal submucosa and is a non-cross-linked
mesh. Likely due to its (proprietary) processing, Biodesign in practice often dissolves
before healing and remodeling can take place.
A novelty on the surgical mesh market is OviTex. It is produced by Aroa Biosurgery and
consist of sterile sheep extracellular matrix (ECM) interwoven with a (absorbable or
non-absorbable) synthetic fiber. OviTex comes with a grid of absorbable polyglycolic acid
(PGA) or permanent polypropylene and with differing amounts of layers (Core, 1S and 2S).
Unique to OviTex is its composition, which consists of essential components required for
regeneration of host tissue. Additionally, the coupling of an ECM with a (absorbable)
synthetic fiber provide strength without the need to cross-link the ECM. Moreover, OviTex
is lower in costs than any other biological mesh on the market. Since the use of
synthetic meshes in pelvic floor surgery has come under scrutiny, patients are tempted to
undergo a resection rectopexy as an alternative to VMR with polypropylene. Apart from the
fact that the resection is associated with a higher risk of complications due to the
application of an anastomosis, the recovery time is much longer. The hospitalization
period would be longer and therefore the costs compared to prolapse surgery with OviTex
would be higher.
Preliminary results of a recent pilot study at Meander MC showed that the use of an
OviTex PGA (with absorbable grid) mesh in the pelvic floor is feasible and safe.
Nevertheless, 2 out of 11 patients who completed follow-up of 6 months showed an early
anatomical recurrence. This suggests that the use of permanent synthetic fiber may be
necessary for a more durable repair and fewer recurrences than using OviTex PGA. Although
resistance against synthetic grafts is growing, OviTex Permanent contains 96% sheep ECM
and only 4% polymer, compared to the standard Prolene mesh which is 100% polymer (polymer
areal density 16g/m2 OviTex 1S vs. 76g/m2 prolene). Furthermore, the polymer is embedded
in the ECM which further attenuates any inflammatory response. Observations in primates
show that the minimized amount of embedded synthetic reinforcement results in an implant
that, histologically, behaves like a biologic mesh yet maintains its functional
structure. This is the first prospective multicenter study using a OviTex 1S mesh.
Although the material ovine was studies before, little is known about the feasibility of
enrolling these patients into randomised studies in the Netherlands and about the
feasibility, safety, and tolerance of the OviTex 1s is this setting. Therefore, the
investigators decided to start with a phase II study. This allows for adequate monitoring
of the feasibility, safety, and tolerance of the experimental treatment.
There are no studies comparing OviTex to the current standard (Prolene, PMN3, Ethicon Inc
Johnson & Johnson, Amersfoort, The Netherlands) Therefore, a comparative study should be
conducted before OviTex is used as a biologic alternative for polypropylene in VMR on a
larger scale. Following the OviTex pilot study, the investigators aim to conduct a
follow-up study (ProTex trial) in which, both in the short and longer term, the efficacy
of the OviTex mesh in pelvic floor surgery will be assessed in comparison with the
current standard polypropylene, by means of a non-inferiority test.