Objective: The reliable animal model of intervertebral disc degeneration, can provide important experimental carrier to research pathogenesis and treatment of intervertebral disc degeneration. To establish three kinds of injury induced rabbit intervertebral disc degeneration models and to compare the characteristics among them by using biochemical and radiological methods.
Methods: Twenty-five healthy New Zealand white rabbits (weighing 2.0-2.5 kg) were randomly divided into 5 groups (n=5). The L(3, 4), L(4, 5) and L(5, 6) discs in each rabbit were used for study. Groups A and B were for annulus puncture with an 18-gauge needle and a 22-gauge needle, respectively; group C was for nucleus aspiration; group D was for endplate injury and group E was used as a control. The lumbar spinal plain radiographs and magnetic resonance images (MRI) were evaluated, the raltive height of intervertebral disc was measured and the grades of disc degeneration were recorded 2, 4, 8, 16, and 32 weeks after operation. The water and the sulfated-glycosaminoglycan (s-GAG) contents of the nucleus were measured after sacrifice (randomly choose one rabbit from each group at each time point).
Results: In groups A, B, C and D, the height of intervertebral space in plain radiograph gradually decreased after operation. The anterior bony excrescences of vertebral body and varying degrees of calcification of endplate were also observed. The signal intensity of disc in T2-weighted magnetic resonance imaging decreased with time too. Compared with group E, the significant changes of height of intervertebral discs and grades of disc degeneration in MRI occurred at different time points within 4 weeks in groups A-D (P < 0.05). The significant change in groups C and D occurred earlier than in groups A and B. The water and s-GAG contents of discs decreased gradually in groups A-D after operation, while the significant change occurred at varying time points within 8 weeks compared with group E (P < 0.05). The apparent downward trend in groups C and D occurred earlier than in groups A and B.
Conclusion: All three methods are successful in inducing intervertebral disc degeneration. The degenerative process induced by endplate injury and nucleus aspiration is faster and more severe than that induced by annulus puncture.