Dorsal arthrodesis in prepubertal New Zealand white rabbits followed to skeletal maturity: Effect on thoracic dimensions, spine growth and neural elements

Abstract

Background:Several studies have shown that severe spinal deformity and early arthrodesis can adversely affect the development of the spine and thorax by changing their shape and reducing their normal function. This article analyzes the consequences of posterior fusion on the growth of spine, thorax and neural elements in New Zealand white rabbits and compares with similar human data.Materials and Methods:The first section of the article analyzes the consequences of T1-T6 dorsal arthrodesis on the growth of the spine, sternum, thorax volume and neural elements in 12 prepubertal female New Zealand white rabbits, through a study of CT scans and histology specimens. The second part, evaluates thoracic dimensions in 21 children with spinal arthrodesis for treatment of deformity performed prior to nine years of age.Results:Dorsal arthrodesis in prepubertal rabbits changes thoracic growth patterns. In operated rabbits thoracic depth grows more slowly than thoracic width. The sternum as well as length of thoracic vertebral bodies in the spinal segment T1-T6 show reduced growth. Children undergoing spinal arthrodesis before nine years of age were noted to have shortened height, short trunk and disproportionate body habitus at skeletal maturity. Observed spine height and chest dimension values were reduced compared to the expected norms. The ratio between chest width and chest depth was below normal values.Conclusions:The first part of the study shows that thoracic dorsal arthrodesis in prepubertal New Zealand white rabbit influences thoracic, spine growth and affects the shape of pseudo unipolar neurons of the dorsal root ganglia. The second part demonstrates that children treated before nine years of age have significantly reduced spine height and thoracic dimensions. The thorax becomes elliptical as chest depth grows less than chest width. Both experimental and clinical findings contribute to explain reduced chest growth and subsequent thoracic growth disturbance in patients treated with early arthrodesis.

Effect of thoracic arthrodesis in prepubertal New Zealand white rabbits on cardio-pulmonary function

“…In their clinical work, Karol et al . confirmed some of the previously published experimental findings 2341011242541. However, our results show that a precocious surgery of a non-deformed spine does not induce cardiopulmonary complications as severe as those found in patients with thoracic insufficiency syndrome.…”

“…Alterations to any of these elements affect and change the development and growth of the others. Therefore, to preserve thoracic motility and permit a normal development of the respiratory tree, treatment should not only focus on the spine but also consider the rib-vertebral-sternal complex as a whole 1011242541…”

“…The inability of the thorax to ensure normal breathing and the accompanying serious respiratory insufficiency is characterized by the thoracic insufficiency syndrome. This clinical picture can be linked to costo-vertebral malformations, neuromuscular disease, syndromes such as Jeune and Jarcho-Levin, or to 50% fusion of the thoracic spine before the age of 7341011242541…”

Thoracic cage plasticity in prepubertal New Zealand white rabbits submitted to T1–T12 dorsal arthrodesis: computed tomography evaluation, echocardiographic assessment and cardio-pulmonary measurements

“…Current data corroborate data of works previously published [13,16,17,19,20]. It appears that moderate and progressive chest volume reduction should be differentiated from severe and deregulated distortion and deformation of the trunk secondary to progressive spinal deformities.…”

“…The varying extent of an experimental arthrodesis also affects differently both growth and thoraco-pulmonary functions [13][14][15][16][17][18][19][20][21][22][23][24]. Clinical data demonstrate that to develop TIS or similar clinical pictures, a significantly reduced spinal height must be present [5,6,13].…”