[Chemical synthesis of biodegradable poly-para-dioxanone and its application for mandibular fracture fixation]

To observe mandibular fracture healing after synthesized bioabsorable poly-para-dioxanone (PDS) ligature fixation.

Para-dioxanone monomer was prepared by chemical reactions of metallic sodium, ethylene glycol and other raw materials. PDS was synthesized by polymerizing the purified para-dioxanone in the presence of catalyst under the conditions of negative pressure and certain temperature. PDS ligature was obtained by processing the polymer into small granules, drying and melt-extruding through a spinnerette. Eighteen adult male New Zealand rabbits were assigned randomly into two groups. After mandibular fracture models were created, reductions of the artificial fractures were accomplished by means of transosseous PDS ligatures on each of 12 rabbits in experimental group. While the other six rabbits without any internal fixation were set as control. Schedules for killing were arranged to give postoperative samples at two-week interval till 12th week.

Radiographical and histological examinations demonstrated that all fractures fixed with PDS ligatures healed without any complication. Periosteal and cartilaginous osteogenesis was observed in newly formed external callus. In contrast, bone fragment migration and the consequent nonunion occurred in the control group. PDS ligature degraded and absorbed without interference with osseous union and healing. The tensile strength reduction of PDS ligature was prior to its absorption in vivo.

The synthesized PDS is a colorless, flexible, themoplastic and monofilament fiber, which can be sterilized by ethylene oxide embalmment without serious loss of tensile strength. It seems that the application of this macromolecular material in internal fixation is of great worth for further study.