Experimental scoliosis in the minipig: study of the vertebral deformities

The purpose of this study was to attempt an induction of a scoliotic deform ation in the minipig by means of unilateral epiphysiodesis of the neurocetr al cartilage (NCC) of 5 consecutive vertebrae, in order to understand the v ertebral deformities genesis in the scoliotic pathology, The vertebral defo rmities 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. Mater ial and methods: Eight Yucatan minipigs (1 month old) have been used. In th e 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 clearin g on the right side at the thoracic level, An X-ray follow-up at 1, 6 and 1 2 months has been performed. The minipigs have been sacrificed between 12 a n 13 months post-operatively. The vertebrae were dissected for the macrosco pic anatomic analysis. Results : The X-ray follow-up shows an unfinished re sorption of the curvature after one year post-operatively. The horizontal d eformity of the vertebrae was more marked in those with the compressed (scr ew) NCC. The vertebral deformities in the minipig are similar to those foun d 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 (postpinealectomie) and the hum an 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 exper imental model for the scoliosis.