Biodegradation of Tissue Separation Spacer Implant

The biodegradation of inflated spacers made of PLCL 70:30 (poly(L-lactide-co-ε-caprolactone)) is investigated. This spacer is intended to temporarily position the anterior rectal wall away from the prostate during radiotherapy of prostate cancer. When inflated with phosphate buffer solution, this spacer implant creates space in the anterior rectum, thereby reducing radiation-induced damage. The mechanical stability of such inflated biodegradable systems over time is highly compromised, and their stability is uncertain due to continuous hydrolysis of the polymer material and imbalance with the muscular pressure that constantly acts on the inflated implant. Herein, detailed in vitro and in vivo degradation data of the inflated spacer are reported and correlated with its stability under a constant mechanical pressure that impersonates the pressure created by the anterior rectum on the spacers. The mechanical and physicochemical test results have a direct correlation with the degradation profile of the PLCL material. Mechanical testing demonstrates spacer inflation for at least 13 weeks.