Bioabsorbable and biodegradable stents in urology.

Since the early 1970s, bioabsorbable polymers have been used increasingly as suture and device materials. Bioabsorbable materials are high-molecular-weight polymers of polylactide (PLA; poly[lactic acid]) or polyglycolide (PGA; poly[glycolic acid]). The mechanical properties of self-reinforced (SR) devices (SR-PGA, SR-PLLA, and SR-PLA96 spiral stents) are acquired by special processing methods from polymer materials. As a result, the spiral stent has an expansion property of up to 70% of its original outer diameter, 50% of which may occur in 30 minutes. The stent may also have variable degradation properties in different parts of the device. The use of bioabsorbable devices in urology is novel. Today, SR-PGA spirals (Biofix) to be used for the prostatic urethra are commercially available but with restrictions. Their indications are the prevention of urinary retention after thermal therapy of prostatic hyperplasia, temporary treatment of urinary retention in patients waiting for surgery, and the early-phase resolution of bladder outlet obstruction in patients waiting for the effect of medical therapy. Stents can be also used to observe the effects of prostatic surgery on bladder function. The SR-PLLA and SR-PLA96 spiral stents are still under development for use in the anterior urethra, prostatic urethra, and ureters. Further experimental and controlled clinical studies are needed to find out the suitability of bioabsorbable devices in urology. Many efforts have been made to discover the best possible materials, models, coating materials, and additives of bioabsorbable stents in urology.