Abstract
The aim of this study was to assess the accuracy of pedicle screw placement comparing Computer Assisted Orthopaedic Surgery equipment with conventional fluoroscopic technique.
Twelve porcine cervical spines were scanned pre-operatively by computer tomography for 3D reconstruction (1 mm slice thickness, 1mm increment and 1 mm pitch).
Computerised 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 diameter, spongiosa) were inserted. Post-operatively, fluoroscopic imaging was used for accuracy assessment by two independent observers, and findings were compared to macroscopic dissection of the spinal segments.
Of 96 pedicles in 12 porcine specimens, 78 received a pedicle screw, 18 screw placements were abandoned, 38 (39.6%) were satisfactorily placed (19 in each, p> 0.05). 40 screws were misplaced, 18 (45%) with the NAVITRAK system vs. 22 (55%) with the conventional technique. These single factor results (all non-significant), were corroborated using a linear logistic regression model. Some heterogeneity in performance was detected between surgeons, independently of the type of technique used.
Computer assisted surgery is an aiming device and is not advantageous over conventional methods in spines with high bone density.
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
