The More the Merrier: Integrating Multiple Models of Skeletal Maturity Improves the Accuracy of Growth Prediction

Accuracy of 4 Different Methods for Estimation of Remaining Growth and Timing of Epiphysiodesis

BACKGROUND

The calculation of remaining growth in children and the timing of epiphysiodesis in those with leg-length discrepancy (LLD) is most often done with 4 methods: the Green-Anderson, White-Menelaus, Moseley straight-line graph, and multiplier methods. The aims of this study were to identify the most accurate method with use of bone age or chronological age and to evaluate the influence of including inhibition in the calculations.

METHODS

One hundred and ninety-one children (10 to 17 years of age) with LLD who underwent surgical closure of the growth plate and were followed until skeletal maturity were identified from a local health register. Patients had at least 2 leg-length examinations with simultaneous bone-age assessments (according to the Greulich and Pyle method), with the last examination performed ≤6 months before surgery. The accuracy of each method was calculated as the mean absolute prediction error (predicted leg length - actual leg length at maturity) for the short leg, the long leg, and the LLD. Comparisons were made among the 4 methods and among calculations made with chronological age versus bone age and those made with versus those without incorporation of a reduced growth rate (inhibition) of the short leg compared with the long leg.

RESULTS

The White-Menelaus method with use of bone age and a fixed inhibition rate was the most accurate method, with a prediction error of 1.5 ± 1.5 cm for the short leg, 1.0 ± 1.2 cm for the long leg, and 0.7 ± 0.7 cm for the LLD. Pairwise comparison of short-leg length and LLD according to the White-Menelaus and other methods showed that they were significantly different (p ≤ 0.002). The calculated inhibition rate did not increase accuracy.

CONCLUSIONS

The White-Menelaus method used with bone age and constant inhibition should be the preferred method when predicting remaining growth and the timing of epiphysiodesis in children between 10 and 17 years of age. One examination is in most cases sufficient for the preoperative clinical investigation when chronological age and bone age are concordant.

LEVEL OF EVIDENCE

Prognostic Level III . See Instructions for Authors for a complete description of levels of evidence.

Percent Final Height Is a Novel Method That Identifies Differences Between the Rate of Development in American Children of Different Races

INTRODUCTION

The Greulich & Pyle (G&P) Radiographic Atlas of Skeletal Development uses hand x-rays obtained between 1926 and 1942 on children of Caucasian ancestry. Our study uses modern Caucasian, Black, Hispanic, and Asian children to investigate patterns of development as a function of percent final height (PFH).

METHODS

A retrospective review, at a single institution, was conducted using children who received a hand x-ray, a height measurement taken within 60 days of that x-ray, and a final height. BA and CA were compared between races. PFH was calculated by dividing height at the time of the x-ray by their final height. To further evaluate differences between races in CA or BA, PFH was then modeled as a function of CA or BA using a fifth-degree polynomial regression, and mean ages at the 85th PFH were compared. Patients were then divided into Sanders stages 1, 2-4, and 5-8 and the mean PFH, CA, and BA of the Asian, Black, and Hispanic children were compared with the White children using Student t test. P values less than 0.05 were considered significant.

RESULTS

We studied 498 patients, including 53 Asian, 83 Black, 190 Hispanic, and 172 White patients. Mean BA was significantly greater than CA in Black males (1.27 y) and females (1.36 y), Hispanic males (1.12 y) and females (1.29 y), and White females (0.74 y). Hispanic and Black patients were significantly more advanced in BA than White patients ( P <0.001). At the 85th PFH, White and Hispanic males were older than Black males by at least 7 months ( P <0.001), and White females were significantly older than Hispanic females by 6.4 months ( P <0.001). At 85th PFH for males, Hispanic and Black males had greater BA than White males by at least 5 months ( P <0.001), and Asian females had a greater BA than Black females by at least 5 months ( P <0.001). Compared with White children, Hispanic children were significantly younger at Sanders 2-4 than White children, and Black children were skeletally older at Sanders 5-8.

CONCLUSIONS

BA was greater than CA by ≥1 year in Black and Hispanic children, and that these children had a significantly greater BA than their White counterparts. Black males and Hispanic females reached their 85th PFH at younger ages, and Hispanic males and Asian females were the most skeletally mature at their 85th PFH. Our results suggest that BA and CA may vary as a function of race, and further studies evaluating growth via the 85th PFH may be necessary.

LEVEL OF EVIDENCE

Therapeutic Study - Level IV.

Correlations Between Eight Comprehensive Skeletal Maturity Systems in a Modern Peripubertal Pediatric Population

BACKGROUND

Several skeletal maturity systems allow for accurate skeletal age assessment from a wide variety of joints. However, discrepancies in estimates have been noted when applying systems concurrently. The aims of our study were to (1) compare the agreement among 8 different skeletal maturity systems in modern pediatric patients and (2) compare these discrepancy trends qbetween modern and historic children.

METHODS

We performed a retrospective (January 2000 to May 2022) query of our picture archiving and communication systems and included peripubertal patients who had at least two radiographs of different anatomic regions obtained ≤3 months apart for 8 systems: (1) proximal humerus ossification system (PHOS), (2) olecranon apophysis ossification staging system (OAOSS), (3) lateral elbow system, (4) modified Fels wrist system, (5) Sanders Hand Classification, (6) optimized oxford hip system, (7) modified Fels knee system, and (8) calcaneal apophysis ossification staging system (CAOSS). Any abnormal (ie, evidence of fracture or congenital deformity) or low-quality radiographs were excluded. These were compared with a cohort from a historic longitudinal study. SEM skeletal age, representing the variance of skeletal age estimates, was calculated for each system and used to compare system precision.

RESULTS

A total of 700 radiographs from 350 modern patients and 954 radiographs from 66 historic patients were evaluated. In the modern cohort, the greatest variance was seen in PHOS (SEM: 0.28 y), Sanders Hand (0.26 y), and CAOSS (0.25 y). The modified Fels knee system demonstrated the smallest variance (0.20 y). For historic children, the PHOS, OAOSS, and CAOSS were the least precise (0.20 y for all). All other systems performed similarly in historic children with lower SEMs (range: 0.18 to 0.19 y). The lateral elbow system was more precise than the OAOSS in both cohorts.

CONCLUSIONS

The precision of skeletal maturity systems varies across anatomic regions. Staged, single-parameter systems (eg, PHOS, Sanders Hand, OAOSS, and CAOSS) may correlate less with other systems than those with more parameters.

LEVEL OF EVIDENCE

Level III-retrospective study.

Cross-sectional data accurately model longitudinal growth in the craniofacial skeleton

Dense, longitudinal sampling represents the ideal for studying biological growth. However, longitudinal samples are not typically possible, due to limits of time, prohibitive cost, or health concerns of repeat radiologic imaging. In contrast, cross-sectional samples have few such drawbacks, but it is not known how well estimates of growth milestones can be obtained from cross-sectional samples. The Craniofacial Growth Consortium Study (CGCS) contains longitudinal growth data for approximately 2000 individuals. Single samples from the CGCS for individuals representing cross-sectional data were used to test the ability to predict growth parameters in linear trait measurements separately by sex. Testing across a range of cross-sectional sample sizes from 5 to the full sample, we found that means from repeated samples were able to approximate growth rates determined from the full longitudinal CGCS sample, with mean absolute differences below 1 mm at cross-sectional sample sizes greater than ~ 200 individuals. Our results show that growth parameters and milestones can be accurately estimated from cross-sectional data compared to population-level estimates from complete longitudinal data, underscoring the utility of such datasets in growth modeling. This method can be applied to other forms of growth (e.g., stature) and to cases in which repeated radiographs are not feasible (e.g., cone-beam CT).