Abstract:

BACKGROUND: At present, the internal fixation materials for rib fractures in thoracic surgery include polylactic acid rib nails and pure titanium embracing devices. There are many clinical control studies on them, but there is no report on the molecular inflammatory response in vivo.

OBJECTIVE: To investigate the inflammatory response of polylactic acid rib nails versus pure titanium embracing fixators in rabbits.

METHODS: Sixteen New Zealand white rabbits (provided by Chengdu Dashuo Co., Ltd.) were divided into experimental group and control group. The right pectoralis major muscle of rabbits in the rib nail group was implanted with polylactic acid rib nails, and the right pectoralis major muscle of rabbits in the embracing fixator group was implanted with pure titanium embracing fixator. Femoral arterial blood was collected 3 days, 1 week, 2 weeks, 1 month, and 3 months after implantation. The concentrations of interleukin 1, interleukin-6, lactic acid and tumor necrosis factor alpha were detected by ELISA method. Three New Zealand white rabbits were taken, and the left pectoralis major muscle was implanted with poly-L-lactic acid rib nail, and the right pectoralis major muscle was implanted with pure titanium rib embracing device. At 1 week and 1 month, three grafted implants were implanted. Peripheral muscle tissue was observed for histopathology. This study was approved by the Medical Ethics Committee of Affiliated Hospital of Chengdu University.

RESULTS AND CONCLUSION: (1) There were no significant differences in the concentrations of interleukin-1, interleukin-6, lactic acid and tumor necrosis factor-α between the two groups at 3 days, 1 week, 2 weeks, 1 month, and 3 months after implantation (P > 0.05). (2) At 1 week, the main pathological changes were necrosis of muscle fibers, infiltration of inflammatory cells and hyperplasia of fibrous tissue in the embracing fixator group, and necrosis of muscle fibers, infiltration of inflammatory cells and hyperplasia of fibrous tissue in the rib nail group. The necrosis degree of muscle fiber was less in the rib nail group than in the embracing fixator group. At 1 month, in the two groups, the number of inflammatory cells decreased, and the necrosis area was basically replaced by proliferated fibrous tissue. In the rib nail group, the muscle tissue morphology was relatively complete, and the area of tissue damage was small. At 3 months, the muscle morphology of the two groups was basically normal, and only a small amount of inflammatory cells infiltrated. (3) The results showed that the inflammatory response of polylactic acid rib nail and pure titanium embracing fixator in rabbits was comparable, without significant difference. Moreover, the concentration of lactic acid was not increased after the implantation of polylactic rib nail.

Key words: polylactic acid rib nail, pure titanium embracing device, inflammatory reaction, animal experiment, control study, histocompatibility, interleukin-1, tumor necrosis factor-α