Greater Trochanter Height: A Quantitative Predictor of Skeletal Maturity.

ABSTRACT

BACKGROUND: The purpose of this investigation was to develop a quantitative and reproductible method for estimating skeletal maturity based on measurements of the height of the bony greater trochanter (GT) using timing to 90% of final height as a gold standard. METHODS: Bony GT height was measured using serial anteroposterior pelvic radiographs in 76 healthy pediatric patients obtained from the Bolton-Brush (BB) Study with corresponding Greulich-Pyle (GP) bone ages. Chronologic age at 90% of final height was calculated. GT height was then measured in 300 contemporary patients aged 4 to 18 years, evenly divided based on sex and race. Bony GT height was compared between BB and contemporary patients, while linear mixed-effects models were used to examine for potential predictors of years to 90% final height using patient sex, GP bone age and bony GT height measurements. RESULTS: Bony GT height was measured in 303 radiographs from the BB Collection (n=37 males; n=39 females) with corresponding GP bone ages, chronological ages, and heights to represent skeletal maturity. Mean age at 90% final height was 13.3±0.6 years for males and 11.4±0.8 years for females. When controlling for patient age and sex, multiple regression analysis revealed that contemporary patients possessed significantly greater bony GT height (mean difference 1.15 mm; P=0.001) when compared with BB patients. Multivariate analysis showed that combining bony GT height, GP bone age, and sex significantly predicted years to 90% total growth (P<0.001) and explained ∼85% (95% confidence interval for R2 82%-87%) of the total variance in years using 90% of final height, with sex, GP bone age, and GT height all significant contributors. CONCLUSIONS: Including bony GT height provides more accurate prediction of 90% final height when combined with GP bone age and sex. GT height offers an efficient and accurate parameter that may be utilized in pediatric orthopedic conditions requiring a quantitative estimate of bone age in children with prior pelvis or hip imaging. LEVEL OF EVIDENCE Level II-diagnostic study.