ABSTRACT

Pedicular screws were used in vertebra deformities for a long time, however, it lead to a limited use of them with the use of thoracolumbar (T 12-L1) and lomber zone, which are believed to be safer, as a result of the penetration of the screws to the spinal canals the formation risk of neurological deficit. In recent years, especially instead of using hooks in the treatment of scoliosis deformations in thoracic zone and hybrid systems consisting of pedicular screws in lomber zone, 3rd generation modern systems were started to use prevalently on pedicular screw applications to all vertebral levels. In this study, it was aimed to determine safe angular interval where screws were installed without any rate of malposition and penetration to the canal or outside the vertebrate substance which happened after the application of transpedicular screw with free hand technique both in thoracic and lomber zone on calf vertebra. With this purpose, 10 fresh calf vertebral columns which were taken out as a whole between T1-L6 were used. In the application of screws to these vertebra, totally 320 double sided 3rd generation pedicular screws were installed on all vertebral levels by 5 inexperienced operators. All of the samples were scanned with 16 cross-section computerized tomography spirally, all screw positions were revised and their angles were measured according to sagital plan.

When all screw applications were evaluated together, it was found that 33 of 360 screws (% 10.3) which were installed had malposition. It was observed that 4 of the screws (%1.2) which had malposition were serious, 24 (%7.5) and 5 (% 1.6) had slightly penetrated. When malposition rates on thoracic and lombar were compared, there was no difference statistically (p>0.05). Without causing any penetration on thoracic zone it was found that 185 screws, which took place in pedicul, were installed with 13.7° ± 5.8°, and safe angular distance was between 4° and 20°. It was determined that safe zone which did not lead to malposition in lomber zone was between 22° and 34°.

As a consequence, it was put forward that fresh calf vertebra was a good model in learning process, and pedicular screw applications by considering similar malposition rates were obtained with surgical and cadaver applications. According to the data of this study, the malposition rates in thoracic and lumbar zone were similar, so long as paying attention to the safe angular zone; it was found that there wasn’t a higher risk of pedicular screw application in the thoracic zone in terms of complication risk in addition to lumbar zone.