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Use of the iPhone for Cobb angle measurement in scoliosis

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Abstract

Purpose

The Cobb technique is the universally accepted method for measuring the severity of spinal deformities. Traditionally, Cobb angles have been measured using protractor and pencil on hardcopy radiographic films. The new generation of mobile ‘smartphones’ make accurate angle measurement possible using an integrated accelerometer, providing a potentially useful clinical tool for assessing Cobb angles. The purpose of this study was to compare Cobb angle measurements performed using a smartphone and traditional protractor in a series of 20 adolescent idiopathic scoliosis patients.

Methods

Seven observers measured major Cobb angles on 20 pre-operative postero-anterior radiographs of Adolescent Idiopathic Scoliosis patients with both a standard protractor and using an Apple iPhone. Five of the observers repeated the measurements at least a week after the original measurements.

Results

The mean absolute difference between pairs of smartphone/protractor measurements was 2.1°, with a small (1°) bias toward lower Cobb angles with the iPhone. 95% confidence intervals for intra-observer variability were ±3.3° for the protractor and ±3.9° for the iPhone. 95% confidence intervals for inter-observer variability were ±8.3° for the iPhone and ±7.1° for the protractor. Both of these confidence intervals were within the range of previously published Cobb measurement studies.

Conclusions

We conclude that the iPhone is an equivalent Cobb measurement tool to the manual protractor, and measurement times are about 15% less. The widespread availability of inclinometer-equipped mobile phones and the ability to store measurements in later versions of the angle measurement software may make these new technologies attractive for clinical measurement applications.

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Notes

  1. Measurement of Cobb angles using the iPhone involved measuring the angle of the inferior and superior vertebral endplates selected and then adding these numbers together to obtain the Cobb angle. Since performing this study, a newer version of the software application enables the addition of the two angles automatically thus avoiding a potential error in simple addition by the observer.

References

  1. Cobb JR (1948) Outline for the study of scoliosis. Am Acad Orthop Surg Instr Course Lect 5:261–275

    Google Scholar 

  2. Kotwicki T (2009) Evaluation of scoliosis today: examination, X-rays and beyond. Disabil Rehabil 30:742–751

    Article  Google Scholar 

  3. Whittle MW, Evans M (1979) Instrument for measuring the Cobb angle in scoliosis. Lancet 1(8113):414

    Article  PubMed  CAS  Google Scholar 

  4. Vrtovec T, Pernus F, Likar B (2009) A review of methods for quantitative evaluation of spinal curvature. Eur Spine J 18:593–607

    Article  PubMed  Google Scholar 

  5. Bland JM, Altman DG (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1(8476):307–310

    Article  PubMed  CAS  Google Scholar 

  6. Bland JM, Altman DG (2003) Applying the right statistics: analyses of measurement studies. Ultrasound Obstet Gynecol 22:85–93

    Article  PubMed  CAS  Google Scholar 

  7. Lenke LG, Betz RR, Harms J et al (2001) Adolescent idiopathic scoliosis: a new classification to determine extent of spinal arthrodesis. J Bone Joint Surg Am 83:1169–1181

    PubMed  Google Scholar 

  8. Shea KG, Stevens PM, Nelson M et al (1998) A comparison of manual versus computer-assisted radiographic measurement: intraobserver measurement variability for Cobb angles. Spine 23:551–555

    Article  PubMed  CAS  Google Scholar 

  9. Ylikoski M, Tallroth K (1990) Measurement variations in scoliotic angle, vertebral rotation, vertebral body height, and intervertebral disc space height. J Spinal Disord 3:387–391

    PubMed  CAS  Google Scholar 

  10. Dutton KE, Jones TJ, Slinger BS et al (1989) Reliability of the Cobb-angle index derived by traditional and computer-assisted methods. Australas Phys Eng Sci Med 12:16–23

    PubMed  CAS  Google Scholar 

  11. Morrissy RT, Goldsmith GS, Hall EC et al (1990) Measurement of the Cobb angle on radiographs of patients who have scoliosis. J Bone Joint Surg Am 72:320–327

    PubMed  CAS  Google Scholar 

  12. Zmurko MG, Mooney JF, Podeszwa DA et al (2003) Inter- and intraobserver variance of Cobb angle measurements with digital radiographs. J Surg Orthop Adv 12:208–213

    PubMed  Google Scholar 

  13. Adam CJ, Izatt MT, Harvey JR et al (2005) Variability in Cobb angle measurements using reformatted computerized tomography scans. Spine 30:1664–1669

    Article  PubMed  Google Scholar 

  14. Facanha-Filho FAM, Winter RB, Lonstein JE et al (2001) Measurement accuracy in congenital scoliosis. J Bone Joint Surg Am A 83(1):42–45

    Google Scholar 

  15. Loder RT, Urquhart A, Steen H et al (1995) Variability in Cobb angle measurements in children with congenital scoliosis. J Bone Joint Surg Br 77:768–770

    PubMed  CAS  Google Scholar 

  16. Carman DL, Browne RH, Birch JG (1990) Measurement of scoliosis and kyphosis radiographs. J Bone Joint Surg Am 72:328–333

    PubMed  CAS  Google Scholar 

  17. Oda M, Rauh S, Gregory P et al (1982) The significance of roentgenographic measurement in scoliosis. J Pediatr Orthop 2:378–382

    Article  PubMed  CAS  Google Scholar 

  18. Heckman JD, Loder RT, Hensinger RN et al (2002) Statistical differences: consider the methodology. J Bone Joint Surg Am 84:1078

    Google Scholar 

  19. Beekman CE, Hall V (1979) Variability of scoliosis measurement from spinal roentgenograms. Phys Ther 59:764–765

    PubMed  CAS  Google Scholar 

Download references

Acknowledgments

The authors wish to acknowledge the contribution of Dr Simon Gatehouse, Dr Sam Martin, Mr Gary Bateman, and Dr Alex Gibson who performed Cobb angle measurements in this study. No financial support was received for this study. None of the authors have any commercial relationship with Apple or with the producers of the Tiltmeter software mentioned in this article.

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Authors and Affiliations

  1. Paediatric Spine Research Group, Queensland University of Technology and Mater Health Services, Brisbane, Australia

    Matthew Shaw, Clayton J. Adam, Maree T. Izatt & Geoffrey N. Askin

  2. Paediatric Spine Research Group, Level 2, Mater Children’s Hospital, Raymond Terrace, South Brisbane, QLD, 4101, Australia

    Clayton J. Adam

  3. Mater Children’s Hospital, Brisbane, Australia

    Paul Licina

Authors
  1. Matthew Shaw
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  2. Clayton J. Adam
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  3. Maree T. Izatt
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  4. Paul Licina
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  5. Geoffrey N. Askin
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Corresponding author

Correspondence to Clayton J. Adam.

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Shaw, M., Adam, C.J., Izatt, M.T. et al. Use of the iPhone for Cobb angle measurement in scoliosis. Eur Spine J 21, 1062–1068 (2012). https://doi.org/10.1007/s00586-011-2059-0

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  • DOI: https://doi.org/10.1007/s00586-011-2059-0

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