Dorsal arthrodesis of thoracic spine and effects on thorax growth in prepubertal New Zealand white rabbits.
METHODS
Dorsal arthrodesis of thoracic spine in a prepubertal New Zealand White rabbit model.


OBJECTIVE
Evaluating the consequences of dorsal arthrodesis on the growth of the spine, sternum, and thorax in prepubertal rabbits, through the study of CT scans.


BACKGROUND
Vertebral arthrodesis in the treatment of progressive idiopathic scoliosis in prepubertal patients is not ideal, but is still a choice in treating major deformities of the spine. Postoperative assessment of spinal deformity is essential, feasible, and recordable through CT scans.


METHODS
Twelve female rabbits, 9 weeks old, were subjected to surgery for dorsal arthrodesis of the upper thoracic spine. Surgery involved the implant of 2 "C"-shaped titanium bars, which were placed beside the spinous processes of the thoracic vertebrae. Three CT scans were performed, 10 (T1), 55 (T2), and 139 (T3) days after surgery. Measures were obtained by Myrian Pro software for 3 different groups: G1 with complete fusion, G2 with incomplete fusion, and G3 sham-operated.


RESULTS
The average of the dorsoventral/laterolateral thoracic diameter ratio at fused levels is lower than 1 in G1 as well as in G2; on the contrary, in G3 is higher than 1. The average growth of the sternum length between T1 and T2 and between T2 and T3 is minor in G1 than in G2 and G3. The dorsal and ventral lengths of thoracic vertebral bodies in the spinal segment D1-D6 is smaller in G1 and G2 than in G3, whereas no differences were observed between the 3 groups in the D7-D12 segment without arthrodesis.


CONCLUSIONS
Dorsal arthrodesis in prepubertal rabbits changes thoracic growth patterns. In operated rabbits, the dorsoventral thoracic diameter grows more slowly than the laterolateral thoracic diameter. The sternum as well as the lengths of thoracic vertebral bodies in the spinal segment D1-D6 grow less. The crankshaft phenomenon is evident at the fused vertebral levels where there is a reduction of thoracic kyphosis.
Canavese
Federico
F
Service de Chirurgie Orthopédique Pédiatrique, CHU Hôpital Lapeyronie, Montpellier, France. canavese_federico@yahoo.fr
Dimeglio
Alain
A
Volpatti
Donatella
D
Stebel
Marco
M
Daures
Jean-Pierre
JP
Canavese
Bartolomeo
B
Cavalli
Fabio
F
D000367:Age Factors; D000375:Aging / Q000502:physiology; D000818:Animals; D001174:Arthrodesis / Q000009:adverse effects*; D005260:Female; D016268:Internal Fixators / Q000009:adverse effects; D011817:Rabbits; D012131:Respiratory Insufficiency / Q000209:etiology / Q000503:physiopathology*; D012143:Respiratory Physiological Phenomena; D012600:Scoliosis / Q000601:surgery; D012741:Sexual Maturation; D013131:Spine / Q000000981:diagnostic imaging / Q000254:growth & development / Q000503:physiopathology; D013249:Sternum / Q000000981:diagnostic imaging / Q000254:growth & development / Q000503:physiopathology; D013904:Thoracic Vertebrae / Q000000981:diagnostic imaging / Q000254:growth & development* / Q000503:physiopathology*; D013909:Thorax / Q000254:growth & development* / Q000473:pathology / Q000503:physiopathology*; D014057:Tomography, X-Ray Computed; D014797:Vital Capacity / Q000502:physiology; D021801:Zygapophyseal Joint / Q000473:pathology / Q000503:physiopathology / Q000601:surgery