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Evidence of the non-linear nature of skeletal maturation
  1. Melanie E Boeyer1,2,
  2. Emily V Leary1,3,
  3. Richard J Sherwood1,2,
  4. Dana L Duren1,2
  1. 1 Orthopaedic Surgery, University of Missouri Columbia, Columbia, Missouri, USA
  2. 2 Pathology and Anatomical Sciences, University of Missouri Columbia, Columbia, Missouri, USA
  3. 3 Missouri Orthopaedic Institute, Thompson Laboratory for Regenerative Orthopaedics, Columbia, Missouri, USA
  1. Correspondence to Melanie E Boeyer, Orthopaedic Surgery, University of Missouri Columbia, Columbia, MO 65211, USA; mebk7d{at}


Objective The aim of this study was to assess longitudinal trajectories of skeletal maturation to determine if children exhibit periods of rapid maturation during normal childhood and adolescence.

Design Retrospective longitudinal study. Patients: 345 participants, with an average of 25 assessments per participant, between 3 and 20 years of age from the Fels Longitudinal Study.

Main outcome measures Chronological age (ie, timing) and rate (ie, tempo) of skeletal maturation, as assessed by the Fels Method, at each maturational milestone, as well as the duration of time spent between any two milestones, were calculated for each participant-specific maturational trajectory and compared between three unique, non-linear maturational trajectory types.

Results More than 81% of participants exhibited a rapid period of skeletal maturation during childhood and/or adolescence, most of whom were characterised by a single maturational spurt during adolescence. Participants with only a single adolescent spurt in skeletal maturation reach adolescent onset and peak approximately 2.8 and 4.2 years earlier, respectively, in boys (p<0.001) and girls (p<0.001), than when compared with participants with both childhood and adolescent spurts. Differences in the timing and tempo of maturational milestones were driven primarily by trajectory type.

Conclusions Rapid changes in skeletal maturation occur during normal childhood and/or adolescence, indicating the presence of a maturational spurt: a developmental phenomenon that has remained largely uncharacterised. This work highlights patterned changes in the timing, tempo and duration of longitudinal skeletal maturation while simultaneously shifting the paradigm that skeletal maturation progresses linearly.

  • skeletal maturation
  • skeletal age
  • bone age

Statistics from


  • Contributors MEB: conceptualisation, investigation, methodology, visualisation, formal analysis, writing (original draft), review and editing. EVL: data curation, methodology, visualisation, formal analysis, writing, review and editing. RJS: resources, methodology, writing, review and editing. DLD: conceptualisation, resources, investigation, data curation, methodology, visualisation, writing, review and editing. All authors approved the final version of the manuscript.

  • Funding This work was supported by funds from the National Institutes of Health (NIH, F31 HD091939 and R01 AR055927). Participant radiographs were collected previously with research funds also provided by the NIH (R01 HD012252).

  • Competing interests None declared.

  • Patient consent for publication Not required.

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

  • Data availability statement Data are availible upon reasonable request according to regulations of the National Institutes of Health and the Fels Longitudinal Study. Requests should be sent to Dr Dana L Duren (

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