Development and Investigation of a Biodegradable Mesh for the Treatment of Stress Urinary Incontinence

Stress urinary incontinence (SUI) is the involuntary loss of urine that occurs during increased intra-abdominal pressure and it is a common condition which often requires surgical correction. The most effective and popular surgical procedure to treat SUI was the mid-urethral sling (MUS) which involves insertion of nondegradable synthetic polypropylene (PP) beneath the urethra. MUS surgery has declined in recent years due to PP-related complications such as erosion and chronic pain. In this thesis, I present a body of work investigating reasons for PPrelated complications, evaluation of recent trends in SUI surgery and present a novel material for MUS surgery. 

We conducted a systematic review to compare rates of erosion and chronic pain after mesh insertion for pelvic organ prolapse (POP) and SUI. We hypothesised that a higher proportion of PP-related complications were occurring after POP surgery due to a high volume of material inserted. In this study we showed that the risk of mesh erosion and chronic pain is significantly higher after surgery for POP compared to SUI and that these significant complications occur within the first year after surgery. 

Secondly, we conducted a study to evaluate the trends in SUI surgery since the 2018 pause on use of the PP MUS in Ireland and to quantify the effect this has had on surgical training. We demonstrated a decline in the rate of SUI surgery reported by consultant surgeons which is worrying for undertreatment of females with SUI. The second finding is a downward trend from 2013 to 2020 in the exposure of surgical trainees to SUI procedures with a resultant decreased interest in the Female Urology subspecialty which will lead to challenges in meeting staffing targets in future. 

The third study aimed to develop a novel biodegradable material for SUI surgery. We developed and evaluated a biodegradable polycaprolactone (PCL) mesh and a PCL composite mesh tissue-engineered with human uterine fibroblasts (HUFs) for SUI surgery by comparing mechanical properties and in vitro biocompatibility to commercially available PP and porcine dermis (PD). Cells on the PCL and 8 composite mesh showed greater viability and produced a greater amount of collagen compared to PP and PD implants. The PCL mesh also showed mechanical properties closest to that of healthy pelvic floor tissue. The results of the studies in this thesis show that PP is unsuitable for SUI surgery and results in significant complications. The decline in the use of PP has led to a decline in SUI surgery which is concerning for undertreatment of females with this condition. We have designed two biodegradable mesh materials for SUI surgery which show superior biocompatibility and mechanical properties than PP and should be evaluated in animal and human trials.