A new system for the anterior restoration and fixation of thoracic spinal deformities using an endoscopic approach.

Abstract

A report on the results of animal experiments in which the authors' new system that enables the anterior correction and fixation of thoracic spinal deformity by use of a thoracic endoscope and small incisions was used. The results suggest that the new approach involving thoracoscopic anterior correction and fusion for thoracic spinal deformity could be adapted successfully for the clinic. To develop a new system that enables the anterior correction and fixation of thoracic spinal deformity by use of a thoracic endoscope and small incisions. Anterior correction and fusion through open thoracotomy have been applied mainly for thoracic scoliosis because this approach provides effective correction with short fusion. However, excellent visualization of the spine during thoracic surgical procedures led to the development of thoracoscopic spine surgery. Therefore, the authors postulated that a thoracoscopic approach could allow not only discectomy but also correction and fusion of the deformed thoracic spine in a single surgical event. The vertebral columns and attached thoracic walls were dissected from fresh porcine cadavers and used in the experimental surgery to evaluate the new system. As a next step, thoracoscopic surgery using this new system was performed on four or five vertebrae of five live pigs with an average weight of 50 kg. Initially, the discs and rib heads were removed through the thoracic wall. For each vertebra, a screw connected to a shaft used as a screw holder was inserted through the thoracic wall in a posterior to anterior direction. Each shaft then was linked outside the body to an outrigger. This outrigger was used to both create and restore scoliosis. A rod then was introduced through the thoracic wall and fixed to the screw heads. The animal experiments clearly showed that it was possible to change the Cobb angles of the spine through the use of the outrigger apparatus. In cadaver experiments, it was possible to create scoliosis and re-store it by 25 degrees to 35 degrees. Also, surgery on live pigs resulted in scoliosis of approximately 30 degrees, which means approximately 5 degrees to 10 degrees for each disc space. The procedures used also demonstrated that it was possible to fix a rod, introduced into the pleural cavity through a port, with screw heads. The use of this system successfully changed the Cobb angle of the spine, which suggests that its use should make it possible to correct spinal deformities. This apparatus also succeeded in fixing the rods in the screw heads, which raises the possibility of its use in spinal fixation. The authors believe that this apparatus could be adapted successfully for clinical use. Studies currently are under way in clinics using the new system.