In vitro study of poly(ethylene terephthalate) implants for long-term durability

Abstract

In vitro investigation was carried out using two loading conditions (applied and pre-loading) and three aqueous chemicals to study the in vivo formation of longitudinal and circumferential cracks in poly(ethylene terephthalate) or PET implants. Scanning electron microscopy determined that in vivo formation of longitudinal cracks can be detected by treating the PET with aqueous NaOH in relaxed and loading conditions; both longitudinal and circumferential cracks can be detected by treating the PET with aqueous NaOH under applied and pre-loading conditions above the yield load. The detected longitudinal and circumferential cracks were similar to those found in PET implants in vivo. Treatments using acid and ammonium hydroxide did not produce any longitudinal or circumferential cracks either in relaxed (zero load) or applied loading conditions. The calculated lifetime was approximately 50 years under zero applied loading conditions and pH of 10–11. The major contributing factor for the premature rupture of medical-grade PET implants resulting in numerous human deaths was physiological load.