Reliability and Validity of Angle of Trunk Rotation Measurement Using Smartphone and 3D Printing Technology in Scoliosis

Abstract

Purpose:The purpose of this study was to compare and analyze the method of measuring the angle of the trunk rotation using a smartphone with 3D smartphone holder compared to a scoliometer, which is a measuring tool used as a method for diagnosing scoliosis in scoliosis patients. Methods: Angle of trunk rotation was measured in 21 subjects diagnosed with scoliosis. scoliometer measurement method, a smartphone measurement method with a 3D smartphone holder, a smartphone blind measurement method with a 3D smartphone holder, a smartphone measurement method without a smartphone holder, a smartphone blind measurement method without a smartphone holder, and a total of five measurement methods were repeated three times for comparison and analysis. Results: The smartphone measurement method with a 3D smartphone holder has excellent intra-rater reliability of angle of trunk rotation (Rater A; ICC3, 2≥ 0.993, Rater B; ICC3, 2≥ 0.992). The smartphone blind measurement method with a 3D smartphone holder has excellent inter-rater reliability of angle of trunk rotation (ICC2, 2≥ 0.968). The scoliometer measurement method had the highest validity (r = 0.976) with the smartphone measurement method with a 3D smartphone holder, and the blind measurement method without a smartphone holder had the lowest validity (r= 0.886). Conclusion: These findings, the angle of trunk rotation measured by the smartphone measurement method with a 3D smartphone holder in scoliosis patients showed high reliability and validity compared to the scoliometer measurement method.

Development and validation of a digital twin for the analog scoliometer

“…Firstly, the 30° scale limit is sometimes exceeded in patients with severe torso rotations. In these cases, clinicians will at times use the digital inclinometer on their smartphones as a proxy scoliometer, which is less accurate (see Fig 1) 22 . Second, it is difficult to make accurate measurements when the patient’s torso cannot be positioned parallel to the ground (as sometimes observed in stiff post-op patients) as the functioning of the scoliometer (analog or smartphone based) relies on gravity and the orientation of the device relative to the ground.…”

“…Despite this, the concept and use of the scoliometer has remained relatively unchanged since its invention, with only minimal effort invested into its digitisation and automation. While the development of digital scoliometer devices 23–26 and smartphone apps 18,22,27,28 has reduced the measurement variabilities associated with the interpretation of scale-limited, parallax-prone analog readings, the clinical translation of such devices has been limited. Furthermore, remote measurement of the ATR is still not possible as even digital scoliometers and smartphones need to be positioned directly on the patient.…”