Like most polyester-based polymers used in manufacturing bioresorbable medical devices, PDO-based materials degrade via bulk erosion where water diffuses within the polydioxanone material and slowly hydrolyzes the polymer chains. Generally, the PDO polymer will first exhibit a decrease in average molecular weight, followed by a decrease in strength, and lastly a decrease in overall mass. Polydioxanone is degraded and metabolized into small molecules that are then excreted, circumventing the need for a surgical procedure to remove the implant. Polydioxanone is also known to be highly biocompatible in comparison to 100% PLA-based materials that exhibit significant inflammatory response due to lactic acid buildup at the implant site.

Polydioxanone is a unique monofilament suture that holds inherent characteristics of the flexibility of its polymer which allows the fabrication of this suture into a monofilament fibre. Its chemical formula is a linear polymer that forms during the process of catalytic polymerization of a heterocyclic compound called p-dioxanone.

Chemical formula: C4H6O3 (O=CH-CH2-0-CH2-CH=O)

The hydrolysis of the PDO polymer begins due to the process of disintegration which forms 2-hydroxy-ethoxy- acetic acid (C4H804) monomers. These then broke down into water and carbon dioxide and are absorbed into the skin.

The stages of PDO disintegration

The process of PDO thread disintegration comprise of two stages:

1. The duration of the first stage is from 3-12 weeks. The strength, weight and shape of the thread during this period is not visibly lost. There are no visible signs of cracks or any damage on the filament surface though it loses 9% of its weight. This implies that during the first 3 months the polymer hydrolysis occurs only on the surface of the filament ( the polydioxanone structure is dense and the water molecules cannot penetrate through it). Therefore the changes in filament strength are not pronounced.
2. In the second stage, the PDO threads begin to show signs of disintegration. The peripheral circular cracks appear on the thread surface which allows the penetration of water molecules inside the structure of filament. Due to the little loss of thread weight, the strength of thread is lost to some extent (during 60 days, thread loses 90% of the strength while losing only 1.5% of the mass).
3. Then the smallest PDO thread fragments are produced which diffuse into filament surface. After that, they diffuse into the surrounding tissues. This process of disintegration cause massive loss of filament mass and finally the thread destruction. Simultaneously, there occurs an increase in the level of local pH (because the acidic hydrolysis products accumulate) which triggers autocatalytic effects resulting in acceleration of PDO degradation.

The ultrastructure of PDO Thread comprises of the knot crystal structure and amorphous regions. The strength of the filaments is determined by this ultrastructure. Due to this structure, the process of hydrolysis is slow. This is the reason that PDO thread remains intact inside the tissues for 4-6 months.

Dongguan Fortune Medical Technology Co., Ltd. (Introduction to absorbable polymer materials)

Dongguan Fortune Medical Technology Co., Ltd. is based on medical monomers and medical degradable polymer polyester materials (biomaterials), with interventional non-implantable devices (absorbable devices) as the core, providing customers with integrated, End-to-end high-end consumables R&D and production services continue to lower the R&D threshold for absorbable medical devices and help customers improve R&D efficiency. Bring more breakthrough treatment plans to patients, and the service scope covers the research and development and production of medical monomers, medical degradable polymer polyester materials (biomaterials), medical absorbable monofilaments/multifilaments, and absorbable medical devices.

In terms of polymer degradable materials, our technical core is based on years of accumulation, and we have mature and proven technical reserves. We have become a pioneer and leader in the Chinese absorbable materials market.