SpringerLink
Log in

Validation of a new method for the radiological measurement of rod curvature in patients with spine deformity

  • Case Series
  • Published:
Spine Deformity Aims and scope Submit manuscript

Abstract

Purpose

The relationship between rod curvature and postoperative radiographic results is a debated topic. One of the reasons of the heterogeneity of the observed results might reside in the lack of a validated and widely employed method to measure the curvature of the rods. Aim of this study was to present and validate a novel method for rod measurement, which is based on routine X-rays and utilizes a regression algorithm that limits manual measurements and the related errors.

Methods

Data from 20 adolescent idiopathic scoliosis/Scheuermann kyphosis (AIS/SK) patients and 35 adult spine deformity (ASD) patients for analysis, with 112 rods in total. An orthogonal reference grid was overlaid on the lateral X-ray; seven points were then marked along each rod and their coordinates recorded in a table. Using these coordinates, a third-order polynomial regression was applied to obtain the rod curvature equation (correlation coefficients > 0.97). Three observers (one surgeon, one experienced and one inexperienced observer) independently applied the developed method to measure the rod angulation of the included patients and performed the measurements twice. The reliability of the method was evaluated in terms of intraclass correlation coefficient (ICC), Bland–Altmann plot and 2SR.

Results

The intra-observer ICCs for all measurements exceed 0.85, indicating an excellent correlation. For the AIS/SK group, the surgeon showed a slightly lower reliability compared to the other two evaluators (0.93 vs 0.98 and 0.98). However, the surgeon showed a higher reliability in measurements of the rods at the lumbar level, both for L1-S1 and L4-S1 (0.98 vs 0.96 and 0.89; 0.97 vs. 0.85 and 0.91, respectively). The variability also showed excellent results, with a mean variability ranging from 1.09° to 3.76°. The inter-observer ICCs for the three measurement groups showed an excellent reliability for the AIS/SK group (0.98). The reliability was slightly lower but still excellent for the lumbar measurements in ASD patients at L1-S1 (0.89) and L4-S1 (0.83). The results of the 2SR for each measured segment were 4.4° for T5-T11, 5.4° for L1-S1 and 5.5° for L4-S1.

Conclusion

The described method represents a reliable and reproducible way to measure rod curvature. This method is based on routine X-rays and utilizes a regression algorithm that limits manual measurements and the related errors.

This is a preview of subscription content, log in via an institution to check access.

Access this article

Log in via an institution

Subscribe and save

Springer+ Basic
EUR 32.99 /Month
  • Get 10 units per month
  • Download Article/Chapter or Ebook
  • 1 Unit = 1 Article or 1 Chapter
  • Cancel anytime
Subscribe now

Buy Now

Price includes VAT (United Kingdom)

Instant access to the full article PDF.

Institutional subscriptions

Fig. 1
Fig. 2

Similar content being viewed by others

Data availability

Data can be made available upon reasonable request.

References

  1. Chen Z, Rong L (2016) Comparison of combined anterior-posterior approach versus posterior-only approach in treating adolescent idiopathic scoliosis: a meta-analysis. Eur Spine J 25:363–371. https://doi.org/10.1007/s00586-015-3968-0

    Article  CAS  PubMed  Google Scholar 

  2. Berlin C, Tielemann S, Quante M, Halm H (2023) Correlation of radiographic parameters and patient satisfaction in adolescent idiopathic scoliosis treated with posterior screw-dual-rod instrumentation. Eur Spine J 32:3140–3148. https://doi.org/10.1007/s00586-023-07849-4

    Article  PubMed  Google Scholar 

  3. Baroncini A, Frechon P, Bourghli A et al (2023) Adherence to the Obeid coronal malalignment classification and a residual malalignment below 20 mm can improve surgical outcomes in adult spine deformity surgery. Eur Spine J 32:3673–3680. https://doi.org/10.1007/s00586-023-07831-0

    Article  PubMed  Google Scholar 

  4. Bao H, Shu S, Yan P et al (2018) Fifteen years and 2530 patients: the evolution of instrumentation, surgical strategies, and outcomes in adolescent idiopathic scoliosis in a single institution. World Neurosurg 120:e24–e32. https://doi.org/10.1016/j.wneu.2018.07.054

    Article  PubMed  Google Scholar 

  5. Celestre PC, Carreon LY, Lenke LG et al (2015) Sagittal alignment two years after selective and nonselective thoracic fusion for Lenke 1C adolescent idiopathic scoliosis. Spine Deform 3:560–565. https://doi.org/10.1016/j.jspd.2015.05.002

    Article  PubMed  Google Scholar 

  6. Glassman SD, Bridwell K, Dimar JR et al (2005) The impact of positive sagittal balance in adult spinal deformity. Spine 30:2024–2029. https://doi.org/10.1097/01.brs.0000179086.30449.96

    Article  PubMed  Google Scholar 

  7. Pesenti S, Clément J-L, Ilharreborde B et al (2022) Comparison of four correction techniques for posterior spinal fusion in adolescent idiopathic scoliosis. Eur Spine J 31:1028–1035. https://doi.org/10.1007/s00586-022-07145-7

    Article  PubMed  Google Scholar 

  8. Potter BK, Lenke LG, Kuklo TR (2004) Prevention and management of iatrogenic flatback deformity. JBJS 86:1793

    Article  Google Scholar 

  9. Moufid AY, Cloche T, Ghailane S et al (2019) Mismatch between rod bending and actual post-operative lordosis in lumbar arthrodesis with poly axial screws. Orthop Traumatol Surg Res 105:1143–1148. https://doi.org/10.1016/j.otsr.2019.03.003

    Article  PubMed  Google Scholar 

  10. Ohrt-Nissen S, Dahl B, Gehrchen M (2018) Choice of rods in surgical treatment of adolescent idiopathic scoliosis: what are the clinical implications of biomechanical properties?—a review of the literature. Neurospine 15:123–130. https://doi.org/10.14245/ns.1836050.025

    Article  PubMed  PubMed Central  Google Scholar 

  11. Ayers R, Hayne M, Burger E (2017) Spine rod straightening as a possible cause for revision. J Mater Sci Mater Med 28:123. https://doi.org/10.1007/s10856-017-5935-2

    Article  CAS  PubMed  Google Scholar 

  12. Pienkowski D, Stephens GC, Doers TM, Hamilton DM (1998) Multicycle mechanical performance of titanium and stainless steel transpedicular spine implants. Spine 23:782–788. https://doi.org/10.1097/00007632-199804010-00008

    Article  CAS  PubMed  Google Scholar 

  13. Solla F, Barrey CY, Burger E et al (2019) Patient-specific rods for surgical correction of sagittal imbalance in adults: technical aspects and preliminary results. Clin Spine Surg 32:80–86. https://doi.org/10.1097/BSD.0000000000000721

    Article  PubMed  Google Scholar 

  14. Le Navéaux F, Aubin C-E, Parent S et al (2017) 3D rod shape changes in adolescent idiopathic scoliosis instrumentation: how much does it impact correction? Eur Spine J 26:1676–1683. https://doi.org/10.1007/s00586-017-4958-1

    Article  PubMed  Google Scholar 

  15. Lafage R, Line BG, Gupta S et al (2017) Orientation of the upper-most instrumented segment influences proximal junctional disease following adult spinal deformity surgery. Spine 42:1570–1577. https://doi.org/10.1097/BRS.0000000000002191

    Article  PubMed  Google Scholar 

  16. Yan P, Bao H, Qiu Y et al (2017) Mismatch between proximal rod contouring and proximal junctional angle: a predisposed risk factor for proximal junctional kyphosis in degenerative scoliosis. Spine 42:E280–E287. https://doi.org/10.1097/BRS.0000000000001883

    Article  PubMed  Google Scholar 

  17. Salmingo RA, Tadano S, Abe Y, Ito M (2014) Influence of implant rod curvature on sagittal correction of scoliosis deformity. Spine J 14:1432–1439. https://doi.org/10.1016/j.spinee.2013.08.042

    Article  PubMed  Google Scholar 

  18. Han L, Ma H, Li Q et al (2023) The association of rod curvature with postoperative outcomes in patients undergoing posterior lumbar interbody fusion for spinal stenosis: a retrospective case-control study. BMC Musculoskelet Disord 24:304. https://doi.org/10.1186/s12891-023-06404-y

    Article  PubMed  PubMed Central  Google Scholar 

  19. Diniz SE, Cordeiro F, Ribau A et al (2022) Postoperative impact of rod bending in the lumbar spine fusion surgery with polyaxial screws - validation of a study. J Orthop 33:112–116. https://doi.org/10.1016/j.jor.2022.07.021

    Article  PubMed  PubMed Central  Google Scholar 

  20. Boissiere L, Guevara-Villazón F, Bourghli A et al (2023) Rod angulation does not reflect sagittal curvature in adult spinal deformity surgery: comparison of lumbar lordosis and rod contouring. Eur Spine J 32:3666–3672. https://doi.org/10.1007/s00586-023-07791-5

    Article  PubMed  Google Scholar 

  21. von Elm E, Altman DG, Egger M et al (2007) The strengthening the reporting of observational studies in epidemiology (STROBE) statement: guidelines for reporting observational studies. Ann Intern Med 147:573–577. https://doi.org/10.7326/0003-4819-147-8-200710160-00010

    Article  Google Scholar 

  22. Bonett DG (2002) Sample size requirements for estimating intraclass correlations with desired precision. Stat Med 21:1331–1335. https://doi.org/10.1002/sim.1108

    Article  PubMed  Google Scholar 

  23. Zou GY (2012) Sample size formulas for estimating intraclass correlation coefficients with precision and assurance. Stat Med 31:3972–3981. https://doi.org/10.1002/sim.5466

    Article  CAS  PubMed  Google Scholar 

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

    Article  CAS  PubMed  Google Scholar 

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

    Article  CAS  PubMed  Google Scholar 

  26. Bowden D, Michielli A, Merrill M, Will S (2022) Systematic review and meta-analysis for the impact of rod materials and sizes in the surgical treatment of adult spine deformity. Spine Deform 10:1265–1278. https://doi.org/10.1007/s43390-022-00556-y

    Article  PubMed  PubMed Central  Google Scholar 

  27. Salmingo RA, Tadano S, Fujisaki K et al (2012) A simple method for in vivo measurement of implant rod three-dimensional geometry during scoliosis surgery. J Biomech Eng 134:054502. https://doi.org/10.1115/1.4006687

    Article  PubMed  Google Scholar 

Download references

Acknowledgements

None.

Funding

No funding was received for this work.

Author information

Authors and Affiliations

  1. Spine Surgery Unit 1, Bordeaux University Pellegrin Hospital, Bordeaux, France

    Daniel Larrieu, Cecile Roscop, Louis Boissiere & Ibrahim Obeid

  2. ELSAN, Polyclinique Jean Villar, Brugge Cedex, France

    Daniel Larrieu, Cecile Roscop, Louis Boissiere & Ibrahim Obeid

  3. IRCCS Ospedale Galeazzi – Sant’Ambrogio, Milan, Italy

    Alice Baroncini

  4. Saint Joseph University of Beirut, Beirut, Lebanon

    Ayman Assi

Authors
  1. Daniel Larrieu
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Alice Baroncini
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. Ayman Assi
    View author publications

    You can also search for this author in PubMed Google Scholar

  4. Cecile Roscop
    View author publications

    You can also search for this author in PubMed Google Scholar

  5. Louis Boissiere
    View author publications

    You can also search for this author in PubMed Google Scholar

  6. Ibrahim Obeid
    View author publications

    You can also search for this author in PubMed Google Scholar

Contributions

Daniel Larrieu: study design, data acquisition/analysis/interpretation, manuscript draft; Alice Baroncini: study design, data acquisition/analysis/interpretation, manuscript draft; Ayman Assi: study design, data interpretation, critical manuscript revision; Cecile Roscop: study design, data interpretation, critical manuscript revision; Louis Boissiere: data acquisition, analysis and interpretation, critical manuscript revision; Ibrahim Obeid: data acquisition, analysis and interpretation, critical manuscript revision.

Corresponding author

Correspondence to Alice Baroncini.

Ethics declarations

Conflict of interest

DL, AB, AA, CR: none. LB: Consultant: Spineart, Spinevision, IO: Royalties: Spineart, alphatec, Clariance, Consultant: Medtronic, Depuy, spinevision Research support: Medtronic, Depuy.

Additional information

Publisher's Note

Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Rights and permissions

Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author self-archiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

Reprints and permissions

About this article

Check for updates. Verify currency and authenticity via CrossMark

Cite this article

Larrieu, D., Baroncini, A., Assi, A. et al. Validation of a new method for the radiological measurement of rod curvature in patients with spine deformity. Spine Deform (2024). https://doi.org/10.1007/s43390-024-00905-z

Download citation

  • Received:

  • Accepted:

  • Published:

  • DOI: https://doi.org/10.1007/s43390-024-00905-z

Keywords

Search

Navigation