In vitro degradation of polydioxanone lifting threads in hyaluronic acid

Recently, some clinicians have proposed implanting polydioxanone (PDO) threads imbibed in hyaluronic acid (HA), arguing that this may reinforce the lifting effects. However, this is controversial because PDO sutures are hydrophilic and the presence of HA could increase the rate of hydrolysis. The aim of this study was to demonstrate the degradation of PDO lifting threads in HA through ultramicroscopy. It was a qualitative research and preclinical trial. Three, 1-cm-long, segments of 23-G PDO threads were immersed in 1.5-mL non-crosslinked HA in previously labeled, sterile microcentrifuge tubes. These were observed by ultramicroscopy at 4× and 10× after 24, 48, and 72 h. Microphotographs taken after 24 h show structural changes in the fibers, presenting an increase in interlaminar spaces and dilution of violet pigmentation. At 48 h, degradation continues. PDO hygroscopy is observed as aqueous content between the peripheral layers and the central core of the thread. At 72 h, as the pigment is released, larger empty spaces are observed in the central column of the thread, and there is disorganization of the peripheral fibrils with fraying all along the fiber. HA induces rapid biodegradation of the PDO thread by hydrolysis beginning 24 h after contact of the thread with the biomaterial. The non-crosslinked HA is a powerful catalyzing agent for hydrolytic degradation of the PDO thread, because this thread is highly hydrophilic. Clinically, embedding PDO threads in HA accelerates biodegradation of the suture.