MMP9 and Spinal instability: Immunohistochemical staining showed that the MMP-9 level increased in the spinal instability group, while MA inhibited the MMP-9 level in the spinal instability + MA group (Fig. 7C, D), also, the Collagen II level was decreased in the spinal instability group, while the Collagen II level was increased in the MA group (Fig. 7C, D).