Normative Femoral and Tibial Lengths in a Modern Population of Twenty-First-Century U.S. Children

Abstract

Background:The Green-Anderson (GA) leg-length data remain the gold standard for the age-based assessment of leg lengths in children despite their methodologic weaknesses. We aimed to summarize current growth trends among a cross-sectional cohort of modern U.S. children using quantile regression methods and to compare the median femoral and tibial lengths of the modern U.S. children with those of the GA cohort.Methods:A retrospective review of scanograms and upright slot-scanning radiographs obtained in otherwise healthy children between 2008 and 2020 was completed. A search of a radiology registry revealed 3,508 unique patients between the ages of 2 and 18 years for whom a standard-of-care scanogram or slot-scanning radiograph had been made. All patients with systemic illness, genetic conditions, or generalized diseases that may affect height were excluded. Measurements from a single leg at a single time point per subject were included, and the latest available time point was used for children who had multiple scanograms made. Quantile regression analysis was used to fit the lengths of the tibia and femur and overall leg length separately for male patients and female patients.Results:Seven hundred patients (328 female and 372 male) met the inclusion criteria. On average, the reported 50th percentile tibial lengths from the GA study at each time point were shorter than the lengths in this study by 2.2 cm (range, 1.4 to 3.3 cm) for boys and 2 cm (range, 1.1 to 3.1 cm) for girls. The reported 50th percentile femoral lengths from the GA study at each time point were shorter than the lengths in this study by 1.8 cm (range, 1.1 to 2.5 cm) for boys and 1.7 cm (range, 0.8 to 2.3 cm) shorter for girls.Conclusions:This study developed new growth charts for femoral and tibial lengths in a modern U.S. population of children. The new femoral and tibial lengths at nearly all time points are 1 to 3 cm longer than traditional GA data. The use of GA data for epiphysiodesis could result in underestimation of expected childhood growth.Level of Evidence:Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Children’s orthopaedics

“…Using a new technique designed to minimize irradiation of children’s bones, a team from Rochester (Minnesota, USA) have attempted to replicate the original study with new data, retrospectively reviewing scanograms and radiographs obtained from 3,508 healthy children between 2008 and 2020. 5 Children with illnesses or conditions that could affect height were excluded from the analysis. Quantile regression analysis was used to determine the femoral and tibial lengths for male and female patients separately.…”

What’s New in Pediatric Orthopaedics

“…Skeletal age and growth have become a hot topic in the literature, with a number of publications introducing new ways to assess skeletal age or offering new normative data. New growth charts were proposed in a study of 700 patients for whom the 50th percentile of tibial length was 2.2 cm longer for boys and 2 cm longer for girls than the Green-Anderson data 58,59 . The 50th percentile of femoral length was 1.8 cm longer for boys and 1.7 cm longer for girls than the Green-Anderson data.…”