MATERIAL and METHODS: Seventy-six dry vertebrae were used for this study, and pedicle entry points and projections of pedicle screw trajectory lines in the lateral and superior aspects of the vertebral body were identified and drawn for each vertebra bilaterally. In each position, all angulations were measured directly before the procedure manually. One hundred and fifty two pedicle screws were inserted as a simulation of screw placement with the guidance of the angle-meter smart app. Accuracy of the method was tested according to the occurrence of bone penetration while the angular deviation of the inserted screws was evaluated in computed tomography images.

RESULTS: The mean deviation for 76 pedicle screws on the right side was 2.30°±1.78° in the horizontal plane and 2.17°±1.57° in the sagittal plane; and on the left side, 3.01°±1.83° in the horizontal plane and 2.38°±1.68° in the sagittal plane. No bone penetration occurred during 152 pedicle screw placements. According to the t-test results, there were significant differences between the two groups in the craniocaudal direction of the right side pedicle screws and in the craniocaudal direction of left sided pedicle screws.

CONCLUSION: The free smartphone app presented here as an angle-meter is a safe digital device for spinal instrumentation procedures. As a prototype of future pedicle screw fixation systems, it should be improved in terms of its feasibility and compatibility with screw probes. This may lead to a useful mobile digital angle-meter for spinal procedures. Keywords : Mobile health, Pedicle screw, Smartphone, Spine