Abstract: BACKGROUND: Scholars at home and abroad consider New Zealand rabbits to be an ideal model animal because of the similar anatomical morphology of the lumbar spine to that of the human lumbar spine. There is a lack of systematic comparison of different ways to establish rabbit intervertebral disc degeneration models under X-ray guidance.
OBJECTIVE: To establish a rabbit model of lumbar disc degeneration using X-ray guided acupuncture, end-plate injection and combined method, and to compare the modeling effects of these three methods.
METHODS: Eighteen 6-month-old New Zealand white rabbits were randomly selected and divided into four groups: acupuncture group, endplate injection group, combined group and blank control group. In the acupuncture group, three consecutive segments of the intervertebral discs (L2/3, L3/4, L4/5) were needled and modeled; in the endplate injection group, 50 μL of anhydrous ethanol was injected at a single point on the endplates of the three consecutive segmental discs; in the combined group, three consecutive segmental intervertebral discs were needled and injected with 50 μL of anhydrous ethanol at four azimuthal points on the endplates of the corresponding segmental discs; and the blank control group received no interventions. X-ray examination was performed to measure the disc height index at 2, 4, and 8 weeks after surgery. The intervertebral disc tissues were then taken for anatomical observation and pathological examination. 
RESULTS AND CONCLUSION: (1) Anatomical examination showed that fibrous annulus rupture, nucleus pulposus degeneration, and total disc structure disorder were the main manifestation in the acupuncture group, endplate injection group, and combined group, respectively. (2) X-ray examination showed that the disc height index showed the most obvious reduction in the acupuncture group at 2 weeks after operation, significant reductions in the endplate injection group at 2 and 4 weeks after operation, and significant reductions in the combined group at 2, 4, and 8 weeks after operation. (3) Pathological examination showed that the fibrous ring structure was damaged and the inner annulus fibrosus protruded inward in the acupuncture group; endplate fissure, disordered arrangement and nucleus loss were observed in the endplate injection group; total disc structure disorder with the nucleus pulposus losing water and shrinking and no obvious border with the broken annulus fibrosus was found in the combined group. To conclude, acupuncture, endplate injection and the modified endplate injection method can establish the rabbit intervertebral disc degeneration model. Compared with the single method, the modified endplate injection method can greatly accelerate and aggravate the degeneration of the intervertebral disc, and can effectively shorten the experiment period.

Key words: tissue engineering, intervertebral disc degeneration, annulus fibrosus puncture, endplate injection, X-ray, New Zealand white rabbit