Abstract
The aim of this study was to assess the accuracy of pedicle screw placement using NAVITRAK, a system of Computer Assisted Orthopaedic Surgery and conventional fluoroscopic technique.
Twelve porcine lumbar spines were scanned pre-operatively by computer tomography for 3-D reconstruction ( 1 mm slice thickness, 1mm increment and 2.5 mm pitch ).
Computer randomisation divided the specimens between surgeons of different experience, and the two pedicles of each vertebral level between the two surgical techniques. Stainless steel screws (6.5 spongiosa) were inserted.
Post-operatively, fluoroscopic- and CT imaging were blindly assessed for accuracy by two independent observers, and compared to macroscopic dissection of the spinal segments.
Of 168 pedicles in 12 porcine specimens, 166 received a pedicle screw. Two pedicle screw placements were abandoned. Sixyty-one screws (73%) were placed satisfactorily with the CAOS system, 56 (67.5%) in the conventional group.
In 26 pedicles the screws were placed unsatisfactorily (12 pedicles (46.2%) with the NAVITRAK system and 14 pedicles (53.8%) with the conventional technique.
The NAVITRAK system in combination with stainless steel screws showed a difference of 5.5% in misplacement in favour for the computer assisted technique.
The abstracts were prepared by Dr C Pither. Correspondence should be addressed to him at the British Orthopaedic Association, Royal College of Surgeons, 35–43 Lincoln’s Inn Fields, London WC2A 3PN
