Evaluation of a novel pedicle probe for the placement of thoracic and lumbosacral pedicle screws

Background: Pedicle screw instrumentation is common in the lumbar spine and is gaining acceptance in the thoracic spine. The pedicle is generally cannulated with a gearshift probe or curette. SafePath (Mekanika, Boca Raton, FL) is an alternative pedicle probe designed for pedicle cannulation. This is a blunt-tipped, nonaggressive drill that seeks the cancellous portion of the pedicle. Objective: The objective of this study was to evaluate the accuracy of this device in comparison with techniques commonly used for pedicle cannulation. Methods: Four osteoligamentous fresh-frozen thoracic to sacral cadaveric spines were studied. The pedicles of one side of each cadaver were cannulated with the SafePath device. The contralateral pedicles were cannulated with either a gearshift probe or a 3-0 cervical curette. The accuracy of pedicle probe placement was evaluated by radiography, computed tomography (CT) scan, and direct observation via dissection. Results: By direct observation, 51 of 128 pedicles were violated (40%). There were not significant differences between the results obtained with the gearshift probe or curette; there were 2 of 22 lumbosacral violations (9%) and 14 of 45 thoracic violations (33%). With the SafePath device, there were 0 of 22 lumbosacral violations (0%) and 34 of 45 thoracic violations (76%). SafePath performed significantly better in the lumbar spine and significantly worse in the thoracic spine. The accuracy for determining pedicle violation was 88% for radiography and 85% for CT. Conclusions: The results of this in vitro study suggest that the SafePath device may represent an alternative to traditional pedicle cannulation techniques in the lumbosacral spine. However, the opposite is true in the thoracic spine, where SafePath performed significantly worse than traditional techniques.