gms | German Medical Science

Objective: Several types of pedicle screw systems have been utilized for spine fusion. All systems are made of stainless steel or titanium, which interferes with imaging techniques, especially MRI (magnetic resonance imaging) and CT (computerized imaging) scans, which decreases the diagnostic value. Evaluation of pedicle screw position, decompression of spinal canal and nerve roots and especially evaluation of tumor progression may become inadequate due to metal artifacts. The purpose of the study is to evaluate a newly developed carbon fiber/Peek pedicle screw system regarding efficient reduction of interference by artifacts with enhanced preservation of imaging details close to implants.

Method: To evaluate the impact of the implants and postoperative artifacts on the imaging, pedicle screws (icotec CF/PEEK PSI 2.0) were implanted in 5 patients monosegmental in the lumbar spine. MRI and CT scans were studied in detail after implantation of pedicle screws and rods made of carbon/ peek.

Results: Handling of the carbon/PEEK screws was found to be equal to stainless steel screws. Radiographic control during surgery needs some training to get used to, but due to markers at the screw tip it is easy to identify the screw position in lateral as well as in anteroposterior X-ray. No artifacts are detectable in MRI and excellent visualization of imaging details close to the implant in CT are found, except around the polyaxial titanium screw head.

Conclusions: Due to the reduction of the amount of metal the diagnostic value of postoperative imaging is increased. This may be especially interesting in the follow-up of spinal tumor diseases and improves the possibility of ion radiation therapy in spinal chordomas after decompression and fusion. Actually screws are presently available only for lumber and lower thoracic spine. Biomechanical and clinical studies have been initiated.