gms | German Medical Science

Objective: The aim of the present study was to investigate the accuracy and safety of percutaneous pedicle screw fixation under fluoroscopic control in patients with single level lumbar instability.

Method: 82 consecutive patients (age 62±13 years) undergoing single level lumbar pedicle screw fixation were evaluated. Indications for surgery were degenerative disease in 76 patients (mostly degenerative spondylolisthesis with stenosis, n=59), and isthmic spondylolisthesis in 6 patients. The Viper II system (DePuy) was used. Yamshidi needles were percutaneously inserted through the pedicles into the vertebral body, and K-wires placed through the needles. AP and lateral fluoroscopic images were used to verify the trajectories of the needles and K-wires. After confirmation of correct placement of the K-wires, skin incisions of 10–15 mm length were performed for each screw, and cannulated screws were slid over the K-wires into the pedicles. Intraoperative data and the results of postoperative clinical examinations were retrospectively evaluated to ascertain complications associated with the pedicle screw implantation. To evaluate the accuracy of pedicle screw placement, CT scans in the axial plane as well as saggital and coronal reconstructions were performed within two days after surgery. Lesions of the pedicle cortex were noted, and medial and lateral perforations were classified in grade 1: 0.1 to 2 mm; 2: 2.1 to 4 mm; 3: 4.1 to 6 mm; 4: >6 mm.

Results: There were no neurological, vascular, or other clinical complications related to the pedicle screw placement. However, postoperative CT scans showed a suboptimal intrapedicular position of 16 out of 328 screws (4.9%). Five of them were medial perforations (1.5%), consisting of four grade 1 and one grade 3 perforation. The remaining 11 (3.4%) were lateral perforations (four grade 1, five grade 2, two grade 3). There were no penetrations of the intervertebral disc. The ventral cortex of the vertebral body was perforated by 16 screws (5.5%). There was no indication for revision procedure due to screw misplacement in any case.

Conclusions: The percutaneous fluoroscopically guided, single level pedicle screw fixation is a safe procedure with a low complication rate. Having regard to the potential advantage of the lower invasiveness and decreased tissue damage of this technique, it should be considered as a useful alternative to the open surgical procedure.