A growing number of reconstructive surgeons advocate for biologic grafts in which the host tissue repopulates the graft with blood vessels, fibroblast infiltration, and subsequent collagen deposition, creating a new tissue layer that lasts after the graft resorbs.13 There are 3 potential outcomes of a biologic graft after surgical implantation: absorption, encapsulation, and remodeling. The first potential outcome is simple absorption of the material. This may occur if the host tissue does not recognize the graft as remodelable and simply forms scar tissue in response to insertion of the graft. This response is similar to what might happen if an absorbable synthetic mesh material, such as polyglycolic acid (eg, Vicryl) was implanted.
As mentioned earlier, another potential response to a biologic material, especially one that has been cross-linked with some chemical, such as gluteraldehyde, is encapsulation. The body will attempt to wall off the material by forming a fibrous capsule around the material.
The most desirable outcome, however, is remodeling, whereby the host tissue sees the graft as a material in which it may re-populate with blood vessels, blood cells, collagen, and growth factors. The anticipated result is that after the biologic graft reabsorbs, the patient is left with a stronger layer of “fascia” beneath the vaginal epithelium.
Clinically available biological grafts
There are currently 5 clinically available biological grafts on the market for pelvic floor reconstructive surgery (see Table). The 2 commercially available xenografts are XenformTM (Boston Scientific Corporation, Marlborough, Massachusetts) and MatriStemTM (ACell, Columbia, Maryland). XenformTM is noncross-linked fetal porcine dermis. During the manufacturing process the matrix undergoes chemical viral inactivation as well as sterilization with ethylene oxide gas. ACell MatriStemTM is a 6-layer acellular and noncross-linked matrix derived from porcine urinary bladder.
The 3 available allografts are: RepliformTM (Boston Scientific Corporation), AxisTM (Coloplast, Minneapolis, Minnesota) and SuspendTM (Coloplast). RepliformTM is an acellular cadaveric, noncross-linked dermal matrix, which is sterilized to ensure clinical safety. AxisTM is a human cadaveric dermal graft (harvested from the back and dorsum of upper leg) and SuspendTM is human fascia lata. The AxisTM and SuspendTM grafts are both noncross-linked and sterilized using a proprietary process (Tutoplast) to prevent the transmission of pathogens. All biological grafts come in a variety of sizes and can be trimmed to the appropriate size for the patient.
Evidence for and against biological grafts
The anterior vaginal wall is the most common site of POP and has the highest recurrence rate of up to 70%.14 Given this, several types of graft material have been used to support the anterior vaginal wall with varying ranges of success. A Cochrane review on the surgical management of prolapse by Maher et al. concluded that the anatomical failure rate was higher in those women who underwent a traditional anterior colporrhaphy (28%) compared with the cohort who had biological graft augmentation (18%).15 There are many reports in the literature of various biomaterials that have been used to augment prolapse surgery. The outcomes of these studies appear to be dependent not only on the types of graft material used, but also on the surgical approach and the points of graft attachment. Meshcia utilized cross-linked porcine dermis (PelvicolTM) at time of anterior colporrhaphy and found that the objective recurrence rate was significantly higher in the anterior colporrhaphy (20/103) group compared to the porcine dermis group (7/98) at 1 year.16 Guerette et al. randomized women to either a traditional anterior colporrhaphy or an anterior repair with bovine pericardium collagen matrix graft reinforcement.17 At 2 years, they found no difference in objective recurrence rates (Ba ≥ -1) and there were no infections or erosions reported in the graft cohort.17 Feldner and colleagues compared traditional anterior colporrhaphy with augmentation with porcine small intestine submucosa (SIS) graft (Fortagen, Organogenesis, Inc., Canton, Massachusetts) and demonstrated an 86.2% anatomic cure rate in the SIS group compared with a 59.3% success rate in the traditional anterior repair group (P = 0.03).18 There was no difference in quality of life measures or rate of dyspareunia between the two groups. Gandhi et al., in a prospective study comparing anterior colporrhaphy alone to anterior repair with cadaveric fascia lata (Tutoplast®, Bard) noted no difference in success rates between the two procedures (71% compared to 82%, P = 0.07 respectively).19
Data are limited evaluating the role of graft augmentation in the posterior compartment. Two trials investigated a traditional posterior colporrhaphy compared with SIS augmentation and surprisingly found that the objective recurrence rate was lower in the traditional colporrhaphy group compared to the SIS graft cohort.20,21 In a prospective cohort study by Altman and colleagues, posterior augmentation with porcine dermis (PelvicolTM) in 23 women resulted in a recurrence rate of 41% at 3 years postoperatively.22 Grimes et al. performed a retrospective review of all posterior repairs performed at a single institution.23 One hundred and twenty-four women underwent a traditional posterior colporrhaphy and 39 women underwent posterior repair with 1 of 3 different biological grafts: non-cross-linked cadaveric dermis (RepliformTM), cross-linked porcine dermis (PelvicolTM), and non-crosslinked porcine dermis (XenformTM).23 They found no improvement in anatomical or functional outcomes with the addition of a graft.23 In a case series, Kohli and Miklos reported a 7% failure rate at 1 year in 30 women who underwent a posterior colporrhaphy with cadaveric dermal graft.24
Sung and colleague in 2008 performed a systematic review of the literature available on this topic and concluded that the literature does not allow for ample assessment of the use of a biological graft for pelvic organ prolapse repair.25 There are limited randomized control trials comparing biological grafts to native tissue repair. Furthermore, the literature is restricted to grafts that are no longer on the market and the current biological grafts that are clinically available have not been studied in randomized control trials. However, a prospective, non-randomized, multicenter study evaluating XenformTM versus native tissue repair for treatment of women with anterior/apical prolapse has finished recruitment and results of this trial should be available in 2019. In addition, ACell is recruiting participants in a non-randomized 3-year clinical trial comparing the safety and effectiveness of MatriStemTM to native tissue repairs for POP. Larger prospective randomized trials need to be undertaken to evaluate if a colporrhaphy with a biological graft is superior to a traditional colporrhaphy for any compartment. Furthermore, quality of life measures need to be addressed to allow for more meaningful conclusions and expand upon the currently incomplete data available.