Lumbar facet joint degeneration contributes to degenerative lumbar scoliosis induced by asymmetric stress in rabbits

Abstract

To investigate the role of lumbar facet joint degeneration in the development of degenerative lumbar scoliosis caused by asymmetric stress. Thirty-six New Zealand white rabbits were randomly divided into 3 groups (n=12): Group A with aspiration of the nucleus pulposus to induce disc degeneration; Group B with removal of the left capsule from the facet joints at L3/4 to L5/6 to induce degeneration; and Group C with both treatments. Springs were deployed on the left adjacent facets at L3/4, L5/6 and L5/6 to stress the facet joints. Serial radiographs were taken at 3 and 6 months, and the facet joint tissues were sampled at 6 months for Safranin O-fast green staining to assess the severity of cartilage degeneration based on the Mankin score. The Cobb angle differed significantly among the 3 groups (F=24.865, P=0.000). In all the groups, the Cobb angles at 6 months increased significantly as compared with that at 3 months (P <0.05). The Cobb angles were significantly greater in group C than in the other 2 groups at both 3 and 6 months (P <0.05) but showed no significant difference between Groups A and B (P>0.05). The severity of facet joint degeneration also differed significantly among the 3 groups (F= 22.009, P=0.000), and was the most severe in group C (P <0.05); facet joint degeneration was more severe in group B than in group A (P <0.05). Facet joint degeneration is an important factor that contributes to the development of degenerative lumbar scoliosis. Disc degeneration and facet joints degeneration can lead to lumbar scoliosis, which in turn aggravates disc degeneration, facet joints degeneration and asymmetric stress, thus forming a vicious circle to further exacerbate lumbar scoliosis.