gms | German Medical Science

60th Annual Meeting of the German Society of Neurosurgery (DGNC)
Joint Meeting with the Benelux countries and Bulgaria

German Society of Neurosurgery (DGNC)

24 - 27 May 2009, Münster

Accuracy of lumbar pedicle screw placement with a bone mounted miniature robotic system

Meeting Abstract

  • I. Pechlivanis - Neurochirurgische Klinik, Universitätsmedizin Mannheim, Medizinische Fakultät Mannheim der Universität Heidelberg
  • A. Harders - Klinik für Neurochirurgie, Ruhr-Universität Bochum
  • K. Schmieder - Neurochirurgische Klinik, Universitätsmedizin Mannheim, Medizinische Fakultät Mannheim der Universität Heidelberg

Deutsche Gesellschaft für Neurochirurgie. 60. Jahrestagung der Deutschen Gesellschaft für Neurochirurgie (DGNC), Joint Meeting mit den Benelux-Ländern und Bulgarien. Münster, 24.-27.05.2009. Düsseldorf: German Medical Science GMS Publishing House; 2009. DocMO.10-07

doi: 10.3205/09dgnc068, urn:nbn:de:0183-09dgnc0685

Published: May 20, 2009

© 2009 Pechlivanis et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License ( You are free: to Share – to copy, distribute and transmit the work, provided the original author and source are credited.



Objective: Pedicle screw placement in lumbar spine surgery is a well-established procedure in spinal neurosurgery. Nevertheless, anatomical variations, obesity and new established minimal invasive systems require a high precision of screw placement. For these reasons the use of spinal navigation systems will be helpful. Furthermore, the use of a navigation system will reduce the applied x-ray radiation.

In this study we evaluated the accuracy of a new miniature robotic system providing passive guidance for pedicle screw placement at the lumbar spine.

Methods: Patients selected for a minimal invasive posterior lumbar interbody fusion were entered into the study. Prior to surgery all patients received a spiral computertomographic (CT) scan according to our protocol. Further steps included the planning of screw placement on the system’s workstation, and intraoperative registration of the system via two radiographs. For surgery the miniature robot was mounted to the spinous process. The robot guided minimal-invasive screw placement passively. Postoperative spiral CT was analysed in axial and longitudinal plane according screw deviation (exactly within the pedicle = group A; <2mm deviation = group B, ≥ 2 mm < 4 mm deviation = group C; ≥ 4 mm < 6 mm deviation = group D; > 6 mm deviation = group E).

Results: PLIF operation was done in 31 patients. A total of 133 pedicle screws were analysed postoperatively. The majority of the screws (n = 58 screws, 43,6%) were placed in L 5. Evaluation of the axial plane showed an excellent placement (group A) in 91.7% of the screws. 6.8% were evaluated as group B. Analysis of the longitudinal plane showed an excellent placement within the pedicle in 81.2% of the screws and 9.8% were evaluated as group B. In one screw (L5 right) slippage on the pedicle wall occurred. In this screw evaluation was done as group C (axial plane) and D (longitudinal plane).

Conclusions: The use of the bone mounted miniature robotic system provides a high accuracy with a deviation <2mm to the surgeon's plan in 91.0–98.5% for lumbar pedicle screw placement.