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Lumbar spine bone mineral density Z-score discrepancies by dual X-ray absorptiometry do not predict vertebral fractures in children
  1. Tasma Harindhanavudhi1,
  2. Anna Petryk2,3,
  3. Richard Jones4,
  4. Amanda Regodón Wallin5,
  5. James S Hodges6,
  6. Sara Van Nortwick7,
  7. Bradley S Miller2,
  8. Tara L Holm4,
  9. Kyriakie Sarafoglou2
  1. 1 Division of Diabetes and Endocrinology, Department of Medicine, University of Minnesota, Minneapolis, Minnesota, USA
  2. 2 Division of Pediatric Endocrinology, Department of Pediatrics, University of Minnesota, Minneapolis, Minnesota, USA
  3. 3 Alexion Pharmaceuticals, Inc., New Haven, Connecticut, USA
  4. 4 Division of Pediatric Radiology, Department of Radiology, University of Minnesota, Minneapolis, Minnesota, USA
  5. 5 Karolinska Institutet, Stockholm, Sweden
  6. 6 Division of Biostatistics, School of Public Health, University of Minnesota, Minneapolis, Minnesota, USA
  7. 7 Department of Orthopaedic Surgery, University of Minnesota, Minneapolis, Minnesota, USA
  1. Correspondence to Dr Tasma Harindhanavudhi, Division of Diabetes and Endocrinology, Department of Medicine, University of Minnesota, Minneapolis MN 55455, USA; hari0049{at}umn.edu

Abstract

Dual X-ray absorptiometry (DXA) remains the most common mode of bone mineral density (BMD) evaluation. In adults, presence of a lumbar spine (LS) BMD T-score discrepancy (>1 SD difference between adjacent vertebrae) can indicate a vertebral fracture. In children, however, the clinical significance of such discrepancies is unknown. We conducted a retrospective study to evaluate the association between LS DXA and LS morphology to elucidate the clinical significance of an LS BMD Z-score discrepancy. We identified 360 DXA scans performed between September 2014 and May 2016 in patients 5–18 years of age. DXA scans were cross-referenced against available LS radiographs and vertebral fracture assessment (VFA) within the 6 months preceding or following a DXA scan. After excluding 44 DXA scans because of spinal hardware, incomplete DXA, or repeat scans, 316 DXA scans were included; 81 (25.6%) had either an LS radiograph or a VFA. Twenty-five of 81 patients (30.9%) had >1 SD difference between adjacent vertebrae in LS BMD Z-score. Two of these 25 patients (8%) had a lumbar vertebral fracture documented by a spine radiograph. Of the remaining 56 patients who did not have a discrepancy >1 SD, 6 patients (11%) had a lumbar vertebral fracture. Discrepancies in LS BMD Z-scores were not associated with lumbar vertebral fractures and, in the absence of fractures, likely represented vertebral developmental variants in children whose skeletons are still growing. Therefore, it does not appear justified to recommend further imaging based solely on the results of a DXA scan without clinically meaningful indications.

  • vertebral fracture
  • children
  • DXA
  • BMD Z-scores

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Footnotes

  • Contributors AP and KS designed the study. TH, AP, RJ, ARW, and SVN collected data for the study. TH, AP, and KS wrote the paper. JSH performed data analysis. TH, AP, JSH, BSM, TLH, and KS revised the manuscript.

  • Funding Research reported in this publication was partially supported by the National Cancer Institute of the National Institutes of Health under award number R01CA181024 to KS.

  • Competing interests None declared.

  • Patient consent Detail has been removed from this case description/these case descriptions to ensure anonymity. The editors and reviewers have seen the detailed information available and are satisfied that the information backs up the case the authors are making.

  • Ethics approval The study was approved by the University of Minnesota Institutional Review Board (IRB code number: 1605M87566).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Correction notice This article has been corrected since it was published Online First. An additional affiliation has been added for author Anna Petryk. The author name ’Amanda R Wallin' has been corrected to ’Amanda Regodón Wallin'.

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