Intraoperativ CT-navigierte Anlage von zevikalen Pedikelschrauben - Eine prospektive single-center Analyse von 655 zervikalen Pedikelschrauben.

Intraoperative (i)CT-navigated screw placement has led to a paradigm shift in dorsal instrumented fusion surgery of the cervical spine. While internal screw-rod systems used to rely heavily on lateral mass screws (LMS), we have discovered a trend towards the use of pedicle screws (CPS) within one year after the implementation of iCT. This study assess accuracy and associated risks of iCT navigated dorsal CPS placement.

A consecutive series of patients that received dorsal instrumented fusion of the c-spine using iCT navigated screw placement between Sep 17 and Feb 23 was prospectively analyzed. A modified Gertzbein&Robbins classification was used for qualitative assessment. Pedicle or transverse foramen breaches of ≥4mm were deemed misplacements. Surgery-related adverse events and follow-up were documented.

The cohort comprises 142 patients with 655 CPS (79.9%). Initial accuracy was 91.6% (acceptably placed screws) and 93% after intraoperative correction of 19 CPS. The accuracy was lower at C3 and C4 levels (88.5 and 79.6%; p <.05). Pedicle breaches were found mainly lateral (55.9%) and medial (36%), rarely sup-/inferior (8%). Transverse foramen was breached in 39.4% of patients resulting in 1 vertebral artery injury (0.7% of all patients; 0.15% of all CPS), followed by cerebellar stroke without fatal course. One screw misplacement resulted in spinal cord injury (0.7% of all patients). No nerve root injury was observed. In total, 6 (4.2%) patients suffered from transient, 4 (2.8%) from permanent neurological deterioration, however only 2 cases were directly related to screw misplacement (1.4%). Eight patients (5.6%) received revision surgery due to infection. Complete follow-up was assessed for 49.7% (n=71) of all patients. Radiological follow-up found 5 cases of osteolytic screw loosening (3.5% of all patients) and 6 cases of broken pedicle screws (4.2%), leading to four cases of revision surgery due to loss of fixation (2.8%).

iCT navigated CPS placement results in very good accuracy. There is a tendency towards lateral pedicle and thus transverse foramen breach. Overcorrection might lead to medial pedicle breach, endangering the spinal cord. Our study shows that screw related adverse events are rare, but may result in severe injury. Even screw-misplacement seldom results in neurological deterioration, nor verifiably in poor biomechanical outcome. However, larger follow-up series are needed to address biomechanical outcome in an adequate manner.