A novel rapid measurement method of cervical sagittal parameters based on the integrated inclinometer of a smartphone: a validity and reliability study

Objectives: A new method was introduced using a smartphone's integrated inclinometer for rapid measurement of sagittal cervical parameters. The present study aims to compare the validity and reliability of the proposed method.Methods: We retrospectively reviewed 120 patients with cervical spondylosis treated at our hospital. The C0-2 Cobb angle, C2-7 Cobb angle, T1-slope (T1S), and neck tilt (NT) were selected as representative sagittal angles for this study. Two methods, the smartphone's integrated inclinometer and picture archiving and communication system (PACS), were used to measure these four representative angles. Validity, reliability, and measurement times were recorded and compared.Results: The representative parameters (C0-2 Cobb angle, C2-7 Cobb angle, T1S, and NT), the ICC was 0.957 (0.939-0.970), 0.971 (0.958-0.979), 0.974 (0.963-0.982) and 0.949 (0.927-0.964) for validity respectively. For the aforementioned representative parameters, the ICC values were 0.972 (0.960-0.980), 0.979 (0.969-0.985), 0.972 (0.959-0.980), 0.942 (0.917-0.959) for intraobserver reliability respectively. For the representative parameters mentioned above, the ICC values were 0.947 (0.926-0.963), 0.964 (0.949-0.975), 0.956 (0.938-0.969), 0.916 (0.881-0.940) for interobserver reliability respectively. For the validity of the representative parameters mentioned above, the Bland-Altman plot displayed a mean difference of 0.2, 0.1, 0.1, and 0.4 degrees with a 95% CI of 4.3, 4.5, 3.4, and 4.1 degrees, respectively. The measurement by smartphone's integrated inclinometer (46.31 +/- 3.99 s) was significantly quicker than that by PACS (69.48 +/- 3.25 s) according to independent-samples T test (p < 0.001).Conclusion: This novel smartphone measurement based on the integrated inclinometer is accurate and reliable for measuring cervical sagittal parameters rapidly and conveniently.