Introduction: Scoliosis progresses within a biomechanical process involving asymmetrical vertebral loading and growth modulation. There is a growing interest in fusionless technique of vertebral stapling for the correction of scoliosis, as it presents less surgical risks and complications than the traditional fusion surgery.
Objectives: This study aims at characterizing the effects of vertebral stapling on vertebral growth rate and growth plate histomorphometry.
Materials and Methods: Twelve female Yorkshire-Landrace pigs aged three months were divided into three groups: loaded (6), sham (3) and control (3). Loaded animals had five staples implanted at levels T6 to T11 for two months. For all animals, postoperative radiographic follow-up included imaging of the spine every two weeks. Growth rate was evaluated using calceine labelling, injected 8 and 2 days prior to sacrifice. Vertebrae were then extracted, fixed and embedded in methymetacrylate. Thin sections of vertebra-disc-vertebra complexes were imaged for growth rate measurements and histomorphometrical analyses.
Results: A scoliotic curve was developed in two loaded animals. Mean growth rates evaluated at the T8-disc-T9 complex reached 15,0, 21,4 and 19,8 for the loaded, sham and control groups respectively.
Conclusion: Vertebral stapling induces spinal curvatures and decreases vertebral growth rate. Staple positioning is critical in the performance to modulate vertebral growth. Complementary histomorphometrical analyses will provide insight on the growth plate response to stapling.
Significance: In vivo mechanobiological studies on the technique of vertebral stapling are required to better characterize the outcome of these fusionless approaches for the correction of scoliosis.