[Preclinical study on the histocompatibility and biomechanics of domestically produced abdominal wall segment...

Objective: To evaluate the histocompatibility and biomechanical properties of domestically produced abdominal wall segment polylactic acid absorbable microhook urethral sling in an animal model. Methods: Twenty four rabbits were divided into two groups: polylactic acid microhook sling group (n=12) and TVT ABBREVO sling group (n=12). Segments of the slings (abdominal wall portion and urethral portion) were implanted into the rabbit's abdominal wall and the vesicovaginal space, respectively. Specimens were harvested via euthanasia at postoperative 0 day (n=3 per group), 4 weeks (n=3 per group) and 12 weeks (n=6 per group) for simulated clinical fixation test, histomorphological observation (to evaluate histocompatibility), and biomechanical property analysis (tensile testing). Results: In the simulated clinical fixation test, the domestically produced abdominal wall segment polylactic acid absorbable microhook urethral sling maintained tight integration with the tissue without detachment across the range of abdominal pressure fluctuations associated with normal human activity (1-34 kPa); in contrast, TVT ABBREVO sling shifted and detached under pressure as low as 15 kPa. At 4 weeks post-implantation in the abdominal wall, none displacement occurred in polylactic acid microhook sling group (0/6 sites), whereas displacement occurred in 5 out of 6 in TVT ABBREVO sling group; at 12 weeks, displacement occurred in 4 out of 24 sites (17%) for polylactic acid microhook sling group, compared to 12 out of 24 sites (50%) for TVT ABBREVO sling group. These differences were statistically significant at both time points (both P<0.01). Tensile testing revealed that the sling of polylactic acid microhook sling group exhibited significantly lower thickness, tensile strength, and elongation percentage after implantation for 12 weeks compared to TVT ABBREVO sling group (all P<0.05). Histocompatibility: both sling types integrated well with host tissues after implantation subcutaneously in the abdominal wall and in the vesicovaginal space. Both induced a mild local inflammatory response. No pathological changes were observed in the surrounding tissues for either sling type, and there were no statistically significant differences in histopathological scores between the two groups (all P>0.05). Conclusions: The domestically produced abdominal wall segment polylactic acid absorbable microhook urethral sling demonstrates favorable histocompatibility. The polylactic acid microhooks significantly enhance the sling's fixation to the tissue, effectively preventing early postoperative displacement caused by abrupt changes in abdominal pressure, and thus offer superior clinical applicability.