Experimental scoliosis in the minipig: study of vertebral deformations

The purpose of this study was to attempt an induction of a scoliotic deformation in the minipig by means of unilateral epiphysiodesis of the neurocetral cartilage (NCC) of 5 consecutive vertebrae, in order to understand the vertebral deformities genesis in the scoliotic pathology. The vertebral deformities induced in this quadruped have been compared to those of the pseudo-biped (chicken: induction of the scoliosis by means of pinealectomy) and to the known vertebral deformities in the human idiopathic scoliosis. MATERIAL AND METHODS: Eight Yucatan minipigs (1 month old) have been used. In the tested group (4 minipigs) underwent an epiphysiodesis (compression with a screw) on the NCC from T5 to T9. The control group (2 minipigs) underwent a perforation of the NCC without a screw placement from T5 to T9. The sham group (2 minipigs) underwent only a sus-periosted vertebral muscles clearing on the right side at the thoracic level. An X-ray follow-up at 1, 6 and 12 months has been performed. The minipigs have been sacrificed between 12 an 13 months post-operatively. The vertebrae were dissected for the macroscopic anatomic analysis. RESULTS: The X-ray follow-up shows an unfinished resorption of the curvature after one year post-operatively. The horizontal deformity of the vertebrae was more marked in those with the compressed (screw) NCC. The vertebral deformities in the minipig are similar to those found in the human and chicken. CONCLUSIONS: Although the curvatures are benign and often spontaneously resolvent, the comparison of the induced vertebral deformities to those obtained in a chicken (post-pinealectomie) and the human suggest that the NCC is likely involved in the vertebral deformities in the horizontal plan. Therefore the minipig does not seem to be a good experimental model for the scoliosis.