Aim:The goal of spinal deformity surgery is to correct curvature in a stable and balanced way. In order to achieve this goal, radiography is used to determine the degree of angles during the operation. However, intraoperative X-ray has several disadvantages, such as suboptimal positioning, radiation exposure, and prolonged operative time. To eliminate these disadvantages, we designed a new device (a metal protractor) to guide the correction process and to measure the intraoperative improvement of the angles in kyphosis surgery. The main purpose of this study is to search the reliability of the device regarding intraoperative measurements in comparison with intraoperative radiograph measurements in kyphosis correction. Material and Methods:Sixty patients having Scheuermann kyphosis underwent correction and fusion surgery with the posterior approach in our clinic between the years of 2010 and 2014. In 16 patients, angles of kyphosis were measured by both the device and X-ray graphics before and after correction intraoperatively. To determine the reliability of the device, intraoperative radiographic measurements were compared with intraoperative measurements calculated by the device. A Pearson correlation coefficient (r) >0.8 is generally considered a very strong correlation, and a P-value <0.05 was regarded as statistically significant.Results:Regarding intraoperative pre-correction measurements of kyphosis angles in 16 patients, a correlation between radiography measurements (mean±SD: 55.87°±8.69°) and device measurements (mean±SD: 57.18°±9.90°) was found (r=0.823, P=0.001). Regarding intraoperative post-correction measurements of kyphosis angles in 16 patients, a correlation between radiography measurements (mean±SD: 40.75°±6.20°) and device measurements (mean±SD: 37.25°±7.59°) was found (r=0.920, P=0.001). Conclusion:The intraoperative measurement device calculated the degree of the angles as meticulously as intraoperative radiography. Since the measurements taken with the device are achieved from the same position and same level, it eliminates inaccuracies arising from patient-cassette relations and from differences regarding how the doctor draws the lines of radiographic measurements.