63 - Low-tension mechanical traction promotes micro/nano environment of endplates in degenerative intervertebral discs

Introduction: Conservative treatment is commonly recommended as the first-line treatment for degenerative disc diseases. Traction therapy has historically been one of the most common methods to address this, but the clinical effect remains controversial.
Aims/

Objectives: To examine the micro/nano environment alterations in intervertebral disc after mechanical traction intervention in a rat model.

Methods: Forty-two six-month-old male Sprague-Dawley rats were randomly divided into six groups: The model group, four coccyx vertebra (Co7-Co10) were fixed with customized external fixators, and the vertebral disc degeneration model was constructed by axial compression of the target Co8-Co9 for 4 weeks. The control group, after successful modeling, the external fixation device was removed and self-rehabilitation was performed. In two intervention groups, Co8-Co9 vertebra were compressed for 4 weeks followed by 2 or 4 weeks of high tension traction (HTT), respectively. In other two intervention groups, vertebra were compressed for 4 weeks followed by 2 or 4 weeks of low-tension traction (LTT), respectively. Imaging tests (X-ray and MRI) were performed to assess disc height and T2 signal intensity at each time point. After the experiment, the animals were euthanized, and the caudal vertebrae were collected for analysis of intervertebral disc histopathology, proteoglycan content, and micro nanostructure of the annulus fibrosis, nucleus pulposus and bony endplate.

Results: Signs of tissue regeneration were apparent in all four intervention groups. After two to 4 weeks of intervention (HTT and LTT), the morphology of pores in the bony endplate, their number, and diameter had recovered significantly compared with those in the model group. The LTT group was superior to the HTT group, and the 4w in situ group was significantly superior to the 2w group. Meanwhile, the histological scores of discs, the mean fibril diameter and modulus of annulus fibrosis were significantly improved compared with the control groups, and the LTT group was superior to HTT group.

Conclusions: Low-tension traction better promotes active reconstruction of bony endplates and improves the elastic modulus and micro/nanostructure of the disc. As a result, it further promotes the regeneration and repair of intervertebral discs.