In patients with moderate to severe incontinence, the artificial urinary sphincter (AUS) remains the treatment of choice with high patient satisfaction rates. While short-term complications following AUS placement are low, long-term removal and/or revision for mechanical failure, urethral atrophy, infection, and erosion can occur in up to half of patients.¹ As survivorship and focus on posttreatment quality of life for patients with prostate cancer increase, it is likely that many men will eventually require AUS revision. Understanding contributing factors to AUS failure and how best to treat these complex patients is increasingly important.

Despite some conflicting data, there are clear risk factors for AUS failure, and understanding these risks can help reduce patient morbidity. Previous studies on AUS revision have identified patients with what is known as a “fragile urethra,” which is defined as a history of radiation, prior AUS, or history of urethroplasty.² The increased failure rate associated with the placement of AUS in patients with a fragile urethra is well recognized. Both radiation and previous urethral surgery can cause urethral fibrosis and microangiopathy that may compromise integrity of the urethral tissue, impair wound healing, limit sphincter cuff support, and increase dissection complexity. Of these risk factors, pelvic radiation has been shown to have the strongest association with increased likelihood of erosion as well as decreased time to erosion events in both primary and secondary AUS procedures.³

The majority of studies evaluating risks that may contribute to AUS revision are small, single-center, retrospective cohort studies, often from university or tertiary care centers. A recent multi-institutional study looking at time to erosion in patients with fragile urethras included patients who received primary AUS placement both within and outside of referral centers, perhaps better representing all AUS patients. Men who had fragile urethras were found to have significantly shorter 1- and 5-year device survival rates of 50.0% and 76.5% at 1 year, and 14.8% and 44.1% at 5 years, respectively.⁴

Notably, the effect of these factors on AUS erosion has been shown to be cumulative, with studies showing both increased chance of AUS failure in patients with all 3 factors of a fragile urethra (pelvic radiation, urethroplasty, or prior AUS) as well as decreased time to failure when compared to patients with only 1 risk factor. A single institutional study showed patients with 1 risk factor had a 34% chance of failure vs a 75% chance of failure when all 3 factors were present.⁵ Another, larger study showed that patients with 0 risk factors had a 2.6% chance of AUS explant vs a 25% chance in those with 3 risk factors present.⁶

The use of a 3.5-cm cuff has also been shown to increase the risk of urethral erosion in patients with a history of radiation, but results are mixed in nonradiated patients.⁷ Transcorporal cuff placement has been shown to have higher rates of erosion, but a recent study suggests protective effects in patients with fragile urethras.⁸ Effects of urethral wrapping on rates of erosion are mixed.

Additional conditions that may impair the microvascular supply to the urethra, such as diabetes mellitus, smoking, and peripheral vascular disease, should also be considered, and the use of androgen deprivation therapy has been linked to increased rates of cuff erosion.⁹ Comorbid conditions and concurrent medications may contribute to, but are not as strongly associated with, AUS failure as surgical and radiation histories.

Despite device and procedural modifications since the AUS was first introduced, the risk of AUS failure remains high, particularly in the fragile urethra. Small (3.5 cm) or transcorporal cuff placement should be used with caution.