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

Study Design. A report on the results of animal experiments in which the au thors' new system that enables the anterior correction and fixation of thor acic spinal deformity by use of a thoracic endoscope and small incisions wa s used. The results suggest that the new approach involving thoracoscopic a nterior correction and fusion for thoracic spinal deformity could be adapte d successfully for the clinic. Objective. To develop a new system that enables the anterior correction and fixation of thoracic spinal deformity by use of a thoracic endoscope and s mall incisions. Summary of Background Data. Anterior correction and fusion through open tho racotomy have been applied mainly for thoracic scoliosis because this appro ach provides effective correction with short fusion. However, excellent vis ualization of the spine during thoracic surgical procedures led to the deve lopment of thoracoscopic spine surgery. Therefore, the authors postulated t hat a thoracoscopic approach could allow not only discectomy but also corre ction and fusion of the deformed thoracic spine in a single surgical event. Methods. The vertebral columns and attached thoracic walls were dissected f rom fresh porcine cadavers and,used in the experimental surgery to evaluate the new system. As a next step, thoracoscopic surgery using this new syste m 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 t he 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 ante rior 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. Results. The animal experiments clearly showed that it;was possible to chan ge the Cobb angles of the spine through the use of the outrigger apparatus. In cadaver store it by 25 degrees to 35 degrees. Also, surgery on live pig s resulted in scoliosis of approximately 30 degrees, which means approximat ely 5 degrees to 10 degrees for each disc space. The procedures used demons trated that it was possible to fix rod, introduced into the pleural cavity through a port, with screw heads. Conclusions. The use of this system successfully changed the Cobb angle of the spine, which suggests that its use should make it possible to correct s pinal deformities. This apparatus also succeeded in fixing the rods in the screw heads, which raises the possibility of its use in spinal fixation. Th e authors believe that this apparatus could be adapted successfully for cli nical use. Studies currently are under way in clinics using the new system.