A new animal model of lumbar disc degeneration in rabbits.

BACKGROUND CONTEXT: There are many models of lumbar disc degeneration, but mechanical stress-induced lumbar disc degeneration is rare. Here we propose a mechanical stress-induced lumbar disc degeneration model to better understand the molecular mechanism of lumbar disc degeneration under stress stimulation.

PURPOSE: To design a new model of lumbar disc degeneration under mechanical stress STUDY DESIGN: The anatomic approach of the oblique lateral approach to lumbar fusion surgery was used to design a longitudinal compression device across the vertebral body of the rabbit to impose longitudinal load on the lumbar disc.

METHODS: New Zealand white rabbits (n=30) were used. Screws were used to cross the rabbits' lumbar vertebral bodies, and both sides of the screws were pressurized. Continuous compression was then performed for 28 days. Adjacent unpressurized lumbar discs serve as controls for pressurized lumbar discs. At 28 days after surgery, micro-computed tomography (CT) and magnetic resonance imaging (MRI) were performed on the rabbits' lumbar discs. After the imaging examination, lumbar disc samples were removed, Safranin-O fast green and immunofluorescence was performed to detect the expression level of intervertebral disc degeneration-related proteins.

RESULTS: The CT results showed that the disc height did not decrease significantly after mechanical loading. The MRI results showed that the signals in the pressurized disc decreased 28 days after loading. The results of Safranin-O fast green showed that the cartilage component of the intervertebral disc after mechanical compression was significantly reduced. The immunofluorescence results showed that the expression of ADAMTS5 and MMP13 protein in the nucleus pulposus of the intervertebral disc after mechanical compression increased, while the expression of SOX9 decreased, and the difference was statistically significant. Aggrecan's protein expression decreased, but was not statistically significant.

CONCLUSIONS: This study designed a reliable model of disc degeneration in rabbits. It is more likely to mimic disc compression in the human body.

CLINICAL SIGNIFICANCE: This animal model can be used as a basic model to study the molecular physiological mechanisms of discogenic low back pain.