Artikel
Accuracy and stability in thoracic and lumbar spinal fusions using a novel cannulated polyaxial screw system: Two-year experience
Genauigkeit und Stabilität bei Instrumentierungen der Brust- und Lendenwirbelsäule mit einem neuartigen, polyaxialen, kanülierten Schraubensystem: Zwei Jahre Erfahrung
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Veröffentlicht: | 11. April 2007 |
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Objective: Dorsal instrumentation with the use of pedicular screws is an established treatment for various diseases such as degenerative instability, trauma, tumor and scoliosis. The insertion of pedicle screws remains a challenging procedure due to the variability in width, height and orientation of spinal pedicles and the proximity of nerve roots. Complications due to misplacement of pedicle screws comprise neurogical lesions as well as instability and screw breakage. Misplacement rates with conventional screw systems are reported to be up to 40 % and up to 11 % under neuronavigation. Screw breakage has been described with a frequency of 3-7 % in former studies using a non cannulated system. The objective of this prospective study is to assess the accuracy and stability of thoracic and lumbar pedicle screws with a novel wire guided cannulated polyaxial screw system.
Methods: The cannulated screw system (XIA Precision®, Stryker) was used in 67 consecutive patients (47 women and 20 men, mean age 67y). The mean follow-up period was 10 months (3-24 months). Three-hundred-twenty-six screws (246 lumbar, 80 thoracic) were placed under fluorsoscopic guidance. The underlying diseases were tumor (n=11), trauma (n=22), degeneration (n=22) and infection (n=7). Patients were evaluated before and after surgery in terms of pain level and neurological condition. Post-operative control of screw positioning was obtained by CT scan followed by plain radiographs at follow up examination. Misplacement was defined as in previous studies as a pedicular cortex perforation of at least 2mm.
Results: In 298 out of 326 (91.4 %) pedicle screws no cortical perforation was observed. 20 cases questionable of pedicular cortex perforation, 6 (1.8 %) cases of 2-4 mm and 5 (1.6 %) cases of over 4 mm misplacement were shown. Three screws had to be revised due to radicular pain in two cases and CSF leakage in one case. In the remaining cases no neurological deficit due to pedicular screw placement was observed. So far no screw breakage or losening has been observed.
Conclusions: The use of this cannulated screw system for the placement of pedicle screws in the thoracic and lumbar spine is safe and accurate with an overall-misplacement rate of 3.4 %. The cannulated design is not associated with a higher rate of screw breakage. The advantages of this technique include easy handling without a time-consuming setup.