Estimating Skeletal Maturity by Segmented Linear Modeling of Key AP Wrist Radiographic Parameters.

Background: The recently described Modified Fels wrist skeletal maturity system (mFels wrist SMS) allows for accurate skeletal maturity estimation using a single anteroposterior wrist radiograph but requires evaluation of 8 parameters. A faster method may have clinical utility in the outpatient setting.

Methods: The 8 anteroposterior wrist radiographic parameters comprising the mFels wrist SMS were analyzed in 80 children. Segmented linear regression and generalized estimating equation (GEE) analyses were used to identify the subsets of parameters most important for accurate skeletal maturity estimation for different patient demographics and parameter scores. This process produced multiple abbreviated Fels wrist skeletal maturity system options (abFels wrist SMS), which require fewer parameters. The accuracy of the resulting abFels wrist SMS options was evaluated and compared with the full 8-parameter mFels wrist SMS, the Greulich and Pyle system (GP) optimized with age and sex data, and the Sanders Hand System (SHS) optimized with age and sex data.

Results: A total of 372 wrist radiographs from 42 girls (age range, 7 to 15 y) and 38 boys (age range, 9 to 16 y) were included. The abFels wrist SMS options required fewer parameters (range, 2 to 7 parameters, one option with 2 to 4 parameters) than the full mFels wrist SMS (8 parameters). Skeletal age estimates produced by the full mFels SMS were more accurate than GP (P<0.001), SHS (P<0.001), and similar to the all of the abFels wrist SMS options (P>0.05). The mFels wrist SMS made fewer outlier estimations (estimation >1 y off from the patient's actual skeletal age) than GP (P<0.05), and made similar rates of outlier estimations compared with SHS (P>0.05) and the abFels wrist SMS options (P>0.05).

Conclusion: An abbreviated version of the Modified Fels wrist SMS estimates skeletal maturity with comparable accuracy to the full version but only requires 2 to 4 parameters for quicker use.