Date of Award

January 2015

Document Type

Open Access Thesis

Degree Name

Medical Doctor (MD)

Department

Medicine

First Advisor

Daniel R. Cooperman

Second Advisor

Jonathan Grauer

Subject Area(s)

Medicine

Abstract

Background: Skeletal maturity scoring systems are used to gauge the amount of growth that a child has experienced and the amount of growth that remains. Studies have shown that skeletal maturity is more closely linked to time of peak height velocity (PHV) than chronological age. At PHV, skeletal maturity is very similar between children regardless of sex. Determination of PHV is important for orthopaedic decisions such as timing of epiphysiodesis and risk of scoliosis curve progression. However, the few existing systems of maturity assessment that can identify PHV have limitations preventing them from being used clinically or from predicting PHV beginning at an early age. Ossification of the calcaneal apophysis has never been fully characterized. We examined the ossification sequence of the calcaneus in relation to timing of peak height velocity (PHV). We compare calcaneal apophyseal ossification to other systems of maturity assessment including the Sanders hand score and the modified Oxford hip score. Also, we compare calcaneal apophyseal ossification to the ossification sequence of the plantar and thenar sesamoids, the triradiate cartilage (TRC), and the iliac apophysis.

Methods: Ninety-four healthy children (forty-nine females and forty-five males) between ages three and eighteen were followed longitudinally through their growth with annual serial radiographs and physical examinations. We had approximately seven hundred serially acquired sets of foot, hip, and hand radiographs. PHV was calculated using the height measurements of each child. We compared to PHV the extent of calcaneal apophyseal ossification, iliac crest apophyseal ossification, Sanders hand scores, thenar and plantar sesamoid appearance, the TRC, and modified Oxford hip scores using radiographs taken on the same day annually over a minimum five year period.

Results: Excursion of the calcaneal apophysis begins with appearance of the ossification center approximately five years prior to PHV and can be divided into six stages that occur over a seven year period. Four of six stages of calcaneal apophyseal ossification and two of eight stages of the Sanders system occur prior to PHV. The areas of overlap of the calcaneal and Sanders stages allow the two maturity systems to be combined for superior localization of maturity. The plantar and thenar sesamoids offer the ability to quickly deduce maturity and clarify stages of the calcaneal and Sanders systems. If the plantar sesamoids are present, and the thenar sesamoids are absent, the child is in between 1.35 to 0.12 years before PHV. Calcaneal stages 0-3, and Sanders hand scores 1-2 are associated with modified Oxford hip scores indicating substantial risk of contralateral SCFE.

Conclusions: Ossification of the calcaneal apophysis can determine skeletal maturity around the time of adolescence. The calcaneal system can best identify maturity in the five years prior to PHV whereas the Sanders system better localizes maturity in time after PHV. Combinations of maturity systems allow for more precise localization of maturity than single systems alone. The calcaneal, Sanders system, and TRC can stratify children at high risk of contralateral SCFE. Identification of the most suitable maturity system to answer a clinical question depends on the certainty of the maturity indicator and the strength of the clinical association. If a maturity indicator is certain, and the clinical association of the maturity indicator is strong, additional maturity measurements are not needed. However, if either the maturity indicator or the clinical association is uncertain, further certainty can be obtained by considering a second maturity marker in conjunction, as shown through the improved power of the combined calcaneal/Sanders system for identification of PHV and prediction of contralateral SCFE.

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This is an Open Access Thesis.

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