Validity and reliability of a novel iPhone method to rapidly measure cervical sagittal parameters | Scientific Reports - Nature.com

All methods were carried retired successful accordance with applicable guidelines and regulations. This survey was approved, and the request for informed consent was waived by the morals committee of The First Affiliated Hospital of Chongqing Medical University.

Patient selection

One 100 consecutive patients admitted to our infirmary diagnosed with cervical spondylotic myelopathy oregon cervical spondylotic radiculopathy were retrospectively reviewed. The inclusion criteria were legible lateral plain films of the cervical spine. The exclusion criteria were kyphosis of the cervical spine.

Measurement methods

Four angles, including the C0-2 Cobb angle, C2-7 Cobb angle, T1S and cervix tilt (NT), were chosen to correspond the sagittal parameters of the cervical spine successful the contiguous research. The C0-2 Cobb space was defined arsenic the included space betwixt the McGregor enactment and the enactment parallel to the C2 little endplate (or the included space that lines perpendicular to the McGregor enactment and the C2 little endplate); the C2-7 Cobb space was defined arsenic the included space betwixt the enactment parallel to the C2 little endplate and the enactment parallel to the C7 little endplate (or the included space that lines perpendicular to the C2 little endplate and the C7 little endplate); T1S was defined arsenic the included space betwixt the T1 precocious endplate and horizontal line; NT was defined arsenic the included space betwixt the vertical enactment and the enactment connecting the precocious extremity of the sternum and the centre of the T1 precocious endplate^3,8,11,12 (Fig. 1).

Figure 1

The explanation of the C0-2 Cobb angle, C2-7 Cobb angle, T1S and NT.

To minimize the measurement deviation, the aforesaid machine surface and the aforesaid iPhone were utilized successful this study. PACS’s intrinsic strategy was utilized to manually measurement cervical sagittal parameters by marking the lines and speechmaking them automatically.

The built-in camera of the iPhone was utilized to instrumentality photos for measurement. To minimize parallax errors, the iPhone screen’s level should beryllium kept parallel to the level of the machine surface erstwhile taking the photo. The built-in photograph edit relation was utilized to rotate the pictures of the X-ray films, allowing the grid lines and standard of rotation space to beryllium identified intelligibly and simultaneously (Fig. 2A–E).

Figure 2

Measurement of the C0-2 Cobb angle, C2-7 Cobb angle, T1S and NT by the iPhone’s intrinsic photograph edit function. (A) The targeted photograph was selected to beryllium edited. (B) The photograph was rotated until the McGregor enactment overlapped oregon was parallel to the horizontal grid lines, and past this space was recorded. (C) The photograph was rotated until the little endplate of C2 overlapped oregon was parallel to the horizontal grid lines, and past this space was recorded. (D) The photograph was rotated until the little endplate of C7 overlapped oregon was parallel to the horizontal grid lines, and past this space was recorded. (E) The photograph was rotated until the precocious endplate of T1 overlapped oregon was parallel to the horizontal grid lines, and this space was recorded. (F) The photograph was rotated until the enactment connecting the sternum’s precocious extremity and the centre of the T1 precocious endplate was overlapping oregon parallel to the horizontal grid lines, and this space was recorded.

To measurement the C0-2 Cobb angle, first, the photograph was rotated until the McGregor enactment was overlapping oregon parallel to the horizontal grid lines, and past this space was recorded; second, the photograph was rotated until the little endplate of C2 was overlapping oregon parallel to the horizontal grid lines, and past this space was recorded; finally, the quality betwixt these 2 angles that represented the C0-2 Cobb space was calculated and recorded (Fig. 2B,C).

To measurement the C2-7 Cobb angle, first, the photograph was rotated until the little endplate of C2 was overlapping oregon parallel to the horizontal grid lines, and past this space was recorded; second, the photograph was rotated until the little endplate of C7 was overlapping oregon parallel to the horizontal grid lines, and past this space was recorded; finally, the quality betwixt these 2 angles that represented the C2-7 Cobb space was calculated and recorded (Fig. 2C,D).

To measurement T1S, the photograph was rotated until the precocious endplate of T1 was overlapping oregon parallel to the horizontal grid lines, and this space was recorded arsenic T1S (because the horizontal enactment ever represented 0°) (Fig. 2E).

To measurement NT, the photograph was rotated until the enactment connecting the precocious extremity of the sternum and the centre of the T1 precocious endplate overlapped oregon was parallel to the horizontal grid lines, and this space was recorded. NT was the supplementary space of this space (if NT was little than 45°, the photograph was rotated until the enactment connecting the precocious extremity of the sternum and the centre of the T1 precocious endplate overlapped oregon was parallel to the vertical grid lines, and this space was recorded arsenic the NT (Fig. 2F).

One attending spine surgeon arsenic the experienced perceiver (observer A) and 1 orthopaedic nonmigratory successful grooming arsenic the inexperienced perceiver (observer B) independently reviewed the radiographs. The observers were blinded to the diligent information. Observer A and perceiver B some took photos from the iPhone and measured the angles independently. To measure the interobserver reliability, the cervical sagittal parameters were measured with the iPhone’s intrinsic photograph edit relation by 2 of the observers. Observer A measured the angles with the iPhone again to measure the intraobserver reliability and with the PACS to measure the validity of the caller iPhone method¹³. The interval betwixt each circular of measurements was much than 2 weeks. The bid of the radiographs was reorganized randomly to alteration imaginable recall. A stopwatch was utilized to grounds the clip of each measurement. To simulate the existent measurement process, the clip of measurement by the PACS began with the input of the radiograph fig into the PACS and ended with the signaling of the angle. The clip of measurement of the iPhone began with the turning connected of the camera relation and ended with the signaling of the angle. Excel 2016 was utilized to grounds the space data.

Statistical analysis

All the information were analysed by SPSS 21.0 blinded. Intraclass correlation coefficients (ICCs) were utilized to measure the validity and the intraobserver and interobserver reliability. The validity of this caller iPhone method was assessed by the PACS measurement taken by perceiver A and the mean outcomes of 2 iPhone measurements taken by perceiver A. The intraobserver reliability was assessed by comparing the outcomes of 2 measurements by perceiver A with the iPhone. The interobserver reliability was evaluated by comparing the outcomes betwixt the mean outcomes of 2 iPhone measurements taken by perceiver A and the lone measurement taken by perceiver B¹³.

A bully ICC is defined arsenic implicit 0.75, a precise bully ICC is defined arsenic implicit 0.85, and an fantabulous ICC is defined arsenic implicit 0.9¹³. A Bland‒Altman plot, with the mean quality and 95% assurance interval (CI) visualized by MedCalc software, was utilized to graphically measure the validity and intra- and interobserver reliability of this caller method. The clip quality of the PACS and iPhone methods was assessed by the times taken by the PACS and the mean clip of 2 measurements of the iPhone taken by perceiver A, which was conducted by an independent-samples T test.

General information

This survey reviewed 100 lateral plain films from cervical spondylotic radiculopathy oregon cervical spondylotic myelopathy patients, including 45 males and 55 females. The mean property was 57.14 ± 11.05 years old. The C0-2 Cobb space measured by the PACS was 21.85 ± 7.62°, and the mean C0-2 Cobb space measured by the iPhone was 21.46 ± 7.24°. The C2-7 Cobb space measured by the PACS was 15.39 ± 9.19°, and the mean C2-7 Cobb space measured by the iPhone was 15.69 ± 9.51°. The effect of T1S measured by the PACS was 24.03 ± 7.40°, and the mean effect of T1S measured by the iPhone was 24.04 ± 7.52°. The NT measured by the PACS was 52.11 ± 6.57°, and the mean NT measured by the iPhone was 52.13 ± 6.77°. The measuring clip by iPhone’s intrinsic photograph edit relation (58.55 ± 4.17 s) was importantly little than that by the PACS (70.40 ± 2.92 s) erstwhile compared by independent-samples T trial (P < 0.001).

Validity

The ICC of validity of the C0-2 Cobb space was 0.960 (0.941–0.973), and the Bland‒Altman crippled revealed that the 95% CI was 4.1°, portion the mean quality was 0.3° (Fig. 3A). The ICC of validity of the C2-7 Cobb space was 0.976 (0.965–0.984), and the Bland‒Altman crippled revealed that the 95% CI was 4.1°, portion the mean quality was 0.2° (Fig. 3B). The ICC of validity of the T1S was 0.980 (0.970–0.986), and the Bland‒Altman crippled revealed that the 95% CI was 2.9°, portion the mean quality was 0.1° (Fig. 3C). The ICC of validity of NT was 0.946 (0.921–0.963), and the Bland‒Altman crippled revealed that the 95% CI was 4.3°, portion the mean quality was 0.1° (Fig. 3D) (Table 1).

Figure 3

Bland‒Altman crippled revealing the quality betwixt the PACS and iPhone measurements for the (A) C0-2 Cobb angle, (B) C2-7 Cobb angle, (C) T1S, and (D) NT. The mean quality is shown arsenic the coagulated lines successful the middle, and the 95% CI is presented arsenic the outer 2 dotted lines.

Intraobserver reliability

The ICC of the intraobserver reliability of the C0-2 Cobb space was 0.966 (0.950–0.977), and the Bland‒Altman crippled revealed that the 95% CI was 3.8°, portion the mean quality was 0.1° (Fig. 4A). The ICC of the intraobserver reliability of the C2-7 Cobb space was 0.983 (0.974–0.988), and the Bland‒Altman crippled revealed that the 95% CI was 3.5°, portion the mean quality was 0.0° (Fig. 4B). The ICC of intraobserver reliability of T1S was 0.971 (0.958–0.981), and the Bland‒Altman crippled revealed that the 95% CI was 3.5°, portion the mean quality was 0.2° (Fig. 4C). The ICC of intraobserver reliability of NT was 0.951 (0.928–0.967), and the Bland‒Altman crippled revealed that the 95% CI was 4.2°, portion the mean quality was 0.0° (Fig. 4D) (Table 1).

Figure 4

Bland‒Altman crippled revealing the intraobserver quality of the iPhone measurement for the (A) C0-2 Cobb angle, (B) C2-7 Cobb angle, (C) T1S, and (D) NT. The mean quality is shown arsenic the coagulated lines successful the middle, and the 95% CI is presented arsenic the outer 2 dotted lines.

Interobserver reliability

The ICC of interobserver reliability of the C0-2 Cobb space was 0.953 (0.930–0.968), and the Bland‒Altman crippled revealed that the 95% CI was 4.4°, portion the mean quality was 0.2° (Fig. 5A). The ICC of interobserver reliability of the C2-7 Cobb space was 0.972 (0.959–0.981), and the Bland‒Altman crippled revealed that the 95% CI was 4.4°, portion the mean quality was 0.3° (Fig. 5B). The ICC of interobserver reliability of T1S was 0.957 (0.937–0.971), and the Bland‒Altman crippled revealed that the 95% CI was 4.3°, portion the mean quality was 0.3° (Fig. 5C). The ICC of interobserver reliability of NT was 0.929 (0.897–0.952), and the Bland‒Altman crippled revealed that the 95% CI was 4.9°, portion the mean quality was 0.4° (Fig. 5D) (Table 1).

Figure 5

Bland‒Altman crippled revealing the interobserver quality of the iPhone measurement for the (A) C0-2 Cobb angle, (B) C2-7 Cobb angle, (C) T1S, (D) NT. The mean quality is shown arsenic the coagulated lines successful the middle, and the 95% CI is presented arsenic the outer 2 dotted lines.

Traditionally, cervical sagittal parameters are measured by drafting lines connected the radiographic films with a marker pen and speechmaking them with a protractor. These tools are not ever carried by doctors, and stained movie and time-consuming issues are concerns that should besides beryllium noted. As the existent golden standard, the PACS method tin measurement the parameters rapidly and accurately. However, the diagnostic of being based connected the machine strategy successful a infirmary renders this method not portable, with nary societal function. Moreover, the PACS is not ever compatible among antithetic hospitals, and the radiographs of 1 infirmary cannot ever beryllium measured successful the strategy of different hospitals¹⁴. With the popularity of physics products, immoderate iPhone apps person been developed to measure orthopaedic parameters. However, defects of these apps, specified arsenic download fees, little stableness compared to that of the intrinsic relation of smartphones, deficiency of updates, and deficiency of applicability to smartphone systems different than the iPhone system, cannot beryllium ignored¹⁰.

Therefore, successful the contiguous research, we introduced a caller measuring method based connected the iPhone’s intrinsic photograph edit relation to measurement cervical sagittal parameters. This caller method has proven utile successful the measurement of lumbar pelvic parameters and hallux valgus parameters^10,14. In the contiguous study, the validity of this caller method with the PACS method was compared, and the intraobserver and interobserver reliability of this caller method were evaluated. The results demonstrated that the ICCs of validity and intraobserver and interobserver reliability were each fantabulous for the 4 tested angles. One survey suggested the usage of 11 degrees to correspond the 95% assurance interval for a measurement quality indicating a existent alteration erstwhile measuring the Cobb space successful lateral spine films¹⁵. One survey revealed that the minimum detectable alteration successful T1S was 5.6 degrees¹⁶. The Bland‒Altman crippled successful this survey showed that nary of the results were beyond this acceptable limit. It is worthy noting that the validity and intraobserver and interobserver reliability of NT were each little than those of the different 3 angles. The imaginable crushed is that the points (the sternum’s precocious extremity and the centre of the T1 precocious endplate) utilized to find the connecting lines of NT were some illegible adjacent connected the selected radiographic films successful this study. Additionally, our results revealed that this caller method is little time-consuming than the PACS method. Other advantages of this caller method see the solving of the occupation of compatibility of radiographs from antithetic hospitals; beardown societal mechanisms by which to stock accusation and sermon objective cases anytime and anywhere; nary request to execute updates oregon marque payments; and stableness and speedy effect of the intrinsic function^10,14.

The innovation of this method is not successful changing the intrinsic measurement mistake of cervical sagittal parameter measurement but successful providing a new, convenient measurement method¹⁷. In this study, the photos were taken connected a vertical machine screen, and it is tenable to speculate that photos taken with films located successful a vertical movie spectator instrumentality could besides usage this caller measuring method. It is important to enactment that the radiographic movie should beryllium kept parallel to the camera erstwhile taking the photos successful lawsuit of parallax error¹⁸. The radiographic films included successful this survey were legible successful presumption of anatomical structures specified arsenic the endplate of the vertebral body, the precocious extremity of the sternum and the hard palate. However, successful existent objective situations, these anatomical structures whitethorn beryllium illegible, and the validity and reliability of the measurement whitethorn decrease.

References

Authors and Affiliations

1. Department of Oncology, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, People’s Republic of China

   Jie Zhang

2. Department of Orthopedic Surgery, People’s Hospital of Chongqing Banan District, Chongqing, 401320, People’s Republic of China

   Chunyang Zhang

3. Department of Orthopedic Surgery, The First Affiliated Hospital of Chongqing Medical University, Chongqing, 400016, People’s Republic of China

   Weiyang Zhong, Zenghui Zhao, Fei Han, Zhenghan Han, Hang Zhang, Tianji Huang & Xiaoji Luo

4. Orthopedic Laboratory of Chongqing Medical University, Chongqing, 400016, People’s Republic of China

   Weiyang Zhong, Zenghui Zhao, Fei Han, Zhenghan Han, Hang Zhang, Tianji Huang & Xiaoji Luo

Contributions

Study conception and design: T.H., X.L. Acquisition, investigation of data: C.Z., W.Z., Z.Z., F.H., Z.H., H.Z. Interpretation of data: J.Z., C.Z., T.H. Draft the manuscript: J.Z., T.H.

Corresponding author

Correspondence to Tianji Huang.

Competing interests

The authors state nary competing interests.

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