Donor fascia in urogynaecological procedures: a canine model

In vivo biomechanical properties of heavy versus light weight monofilament polypropylene meshes. Does the knitting pattern matter?

AIMS

This work evaluated the post-implant biomechanical properties of light-weight (LW) and heavy-weight (HW) monofilament polypropylene (PP) meshes with different knitting patterns in an animal model in vivo.

METHODS

Forty-five adult female Wistar rats were divided into three groups and randomly implanted with 32 × 32 mm HW-PP (62 gm^-2 ) orLW-PP (16 gm^-2 ) in the lower abdomen. LW-PPwas tested orthogonally (called LWL and LWT) to reproduce the longitudinal and transverse planes of the vaginal wall, respectively. Abdominal walls were removed at 7, 30, and 60 days, and then tested for tensile load (maximum load until avulsion from the tissue), deflection, and stiffness to maximum load. Explants were compared over time and between groups.

RESULTS

LW-PP meshes implanted in the LWT fashion (vaginal transverse plane) showed comparable maximum load and stiffness to HW-PP meshes, and LW-PP meshes implanted in the LWL fashion (vaginal longitudinal plane) presented lower maximum load and stiffness than the HW-PP meshes. There were no significant differences in the values of deflection at maximum load between the studied meshes as a function of time.

CONCLUSIONS

The final mechanical behavior of PP mesh can be changed by its weight and knitting pattern. These properties may be useful in making more biocompatible prostheses for pelvic organ prolapse (POP) with less foreign material to maintain longitudinal vaginal elasticity and minimize sexual symptoms while maintaining transverse resistance (i.e., between vaginal fornixes) to prevent POP recurrence. Neurourol. Urodynam. 36:73-79, 2017. © 2015 Wiley Periodicals, Inc.

Long-term histologic response to synthetic and biologic graft materials implanted in the vagina and abdomen of a rabbit model

OBJECTIVE

We sought to evaluate the effects of graft type, site of implantation, and ovariectomy on the long-term histologic response to graft materials used in pelvic reconstructive surgery.

STUDY DESIGN

In all, 45 rabbits underwent ovariectomy or sham laparotomy and were implanted with polypropylene (PP) mesh (n = 23) or cross-linked porcine dermis (PS) (n = 22) in the vagina and abdomen. Grafts were harvested 9 months later and were processed for histology to evaluate the host inflammatory response and degree of tissue incorporation within the grafts.

RESULTS

Polypropylene induced a milder (P < .007), more uniform response than PS, whereas PS elicited a more variable response and degraded by 9 months. Vaginal grafts had higher scores for inflammation (P = .005) and neovascularization (P < .001), and had lower scores for fibroblastic proliferation (P < .001) than abdominal grafts. Ovariectomy had no effect (P > .05).

CONCLUSION

Synthetic and biologic grafts evoke different foreign body responses, which may have implications for surgical outcomes in women.

Biomechanical properties of synthetic and biologic graft materials following long-term implantation in the rabbit abdomen and vagina

OBJECTIVE

We sought to evaluate the effects of anatomic location and ovariectomy on biomechanical properties of synthetic and biologic graft materials after long-term implantation.

STUDY DESIGN

A total of 35 rabbits underwent ovariectomy or sham laparotomy and were implanted with polypropylene (PP) mesh (n = 17) or cross-linked porcine dermis (PS) (n = 18) in the vagina and abdomen. Grafts were harvested 9 months later and underwent mechanical properties testing.

RESULTS

After implantation, PS was similar in strength (P = .52) but was twice as stiff as PP (P = .04) and had a maximal elongation only half that of PP (P < .001). Degradation of PS was associated with decreased ultimate tensile strength (P = .03) and elastic modulus (P = .046). Vaginal PP grafts shrunk more (P < .001) and were less stiff than abdominal PP grafts (P = .049) but were not different in strength (P = .19). Ovariectomy had no effect (P > .05).

CONCLUSION

Cross-linked PS undergoes long-term degradation resulting in compromised biomechanical properties and thus is likely inferior to lightweight PP meshes for pelvic organ prolapse and incontinence procedures.

Histologic evaluation of human cadaveric fascia lata in a rabbit vagina model

The purpose of this study was to evaluate the histologic response of human cadaveric fascia lata after vaginal implantation. Freeze-dried, gamma-irradiated cadaveric fascia lata from three lots was implanted between the rectovaginal membrane and vaginal epithelium in New Zealand white rabbits. Rabbits were killed at 2, 4, 8, and 12 weeks after implantation. At necropsy, gross findings were described and specimens for routine cultures were taken. Histologic evaluation determined graft integrity, neovascularization, inflammatory response, and host tissue incorporation. Nine rabbits were available for histologic analysis and 14 for gross and microbiologic analysis. Vaginal erosions occurred with three grafts. The remainder were adherent to the surrounding tissues. Erosion was associated with bacterial colonization of the graft. Autolysis of one graft occurred at 4 weeks. Over time, the inflammatory response decreased and neovascularization increased; by 12 weeks, the graft collagen was replaced by host collagen. Cadaveric fascia lata serves as scaffolding for host tissue incorporation with replacement by host collagen.

Abdominal sacral colpopexy with allograft fascia lata: one-year outcomes

OBJECTIVE

The purpose of this study was to assess 1-year outcomes of sacral colpopexy with the use of allograft fascia lata.

STUDY DESIGN

Records of all subjects who underwent sacral colpopexy with allograft fascia lata from May 1, 2001, to April 30, 2003, were reviewed. Subjects underwent pre- and postoperative evaluation of prolapse with the pelvic organ prolapse quantification system. The Fisher's exact test was used to analyze the results.

RESULTS

Allograft fascia lata was used for 24 colpopexies during this period. No significant intraoperative or postoperative complications or graft erosions occurred. Five subjects were lost to follow-up after 3 months. Analysis was performed on the remaining 19 subjects. Prolapse of stage 2 or more in compartments Aa, Ba, Ap, Bp, and C was preoperatively 50%, 74%, 78%, 84%, and 68% and postoperatively 11%, 16%, 21%, 26%, and 5%, respectively.

CONCLUSION

Allograft fascia lata may be a suitable alternative to permanent mesh for sacral colpopexy, but longer-term outcomes and larger studies are needed.

Surgical outcome of abdominal sacrocolpopexy with synthetic mesh versus abdominal sacrocolpopexy with cadaveric fascia lata

Nineteen women who had an abdominal sacrocolpopexy (ASC) with synthetic mesh and 18 women who had an ASC with freeze-dried, irradiated cadaveric fascia lata returned for blinded pelvic organ prolapse quantification (POPQ) examinations. The mean relative vaginal descent (delta) from perfect total vaginal length in the mesh group was 1.1 (0.3) cm, and the delta in the fascia group was 2.8 (0.8) cm (p=0.02, Mann-Whitney U). The proportion of women with "optimal" surgical outcome in the mesh group was 89% and 61% in the fascia group (p=0.06, Fischer's exact test). This study suggests that cadaveric fascia lata may not be a good choice for ASC.

Abdominal Sacral Colpopexy Using Autologous Fascia Lata

PURPOSE

Numerous techniques and materials have traditionally been used to correct vaginal vault prolapse, including cadaveric fascia, synthetic materials and autologous rectus fascia. We report our experience with autologous fascia lata used for abdominal sacral colpopexy.

MATERIALS AND METHODS

A retrospective review identified all women who underwent abdominal sacral colpopexy using autologous fascia lata for vaginal vault prolapse with at least 18 months of followup. Preoperative and postoperative pelvic organ prolapse quantification (POP-Q) scores, relevant clinical and operative parameters, treatment efficacy, harvest site morbidity and patient satisfaction were assessed.

RESULTS

Ten women underwent this procedure between 1999 and 2001. Mean patient age was 68.3 years (range 55 to 82). Followup was 19 to 42 months (mean +/- SD 30.5 +/- 7.78). Preoperatively POP-Q stages were II to IV in 3, 5 and 2 cases, respectively. Postoperative POP-Q scores improved to and remained at stage II or lower in all 10 patients. Mean operative time was 182 +/- 40.94 minutes (range 136 to 265). Mean blood loss was 107.5 +/- 50.07 cc (range 50 to 200). There was no morbidity associated with fascia lata harvest. Eight of the 9 women alive at review completed and returned the survey. When asked if they could return to how they were before surgery, would they still have the same procedure done and would they recommend the procedure to a friend, all respondents answered yes to each question.

CONCLUSIONS

Autologous fascia lata compares favorably in efficacy to that reported for other materials in the contemporary literature and it is not associated with any significant morbidity.

Changes in tensile strength of cadaveric human fascia lata after implantation in a rabbit vagina model

PURPOSE

We determined changes in tensile properties after vaginal implantation of human cadaveric fascia lata.

MATERIALS AND METHODS

Baseline tensile properties were determined for freeze-dried, gamma irradiated human cadaveric fascia lata from 3 separate lots. Fascial strips (2 x 0.5 cm.) from 2 lots were implanted between the rectovaginal membrane and vaginal mucosa in New Zealand white rabbits. The strips were excised en bloc 12 weeks after implantation. Tensile property measurements were repeated and compared with pre-implantation values.

RESULTS

Pre-implantation interlot and intralot variability in baseline tensile properties was significant. After implantation there was an approximate 90% decrease in tensile strength from baseline values. There was no gross evidence of graft autolysis.

CONCLUSIONS

The decrease in tensile strength of cadaveric fascial graft was significant after implantation in this model.