Systematic Isolation of Key Parameters for Estimating Skeletal Maturity on AP Hip Radiographs

Abstract

Background:The ability to estimate skeletal maturity using a hip radiograph does not yet exist, but may have utility in the treatment of scoliosis, slipped capital femoral epiphysis, and lower limb deformity. We sought to develop a fast, accurate, and reproducible method. Methods: Fourteen hip radiologic parameters were evaluated on serial anteroposterior hip radiographs from 3 years before to 2 years after the skeletal age associated with 90% of final height, a validated skeletal maturity definition which correlates with the timing of peak height velocity. The Greulich and Pyle (GP) left hand bone age was obtained for comparison. Stepwise linear regression and generalized estimating equation analyses were used to isolate key hip and demographic parameters, creating the "optimized Oxford" skeletal maturity system. The accuracy of the optimized Oxford system in predicting years from 90% of final height was evaluated and compared with systems of demographics only, the modified Oxford, demographics+modified Oxford, and demographics+GP. Results: A total of 284 hip radiographs from 41 girls (range: 7 to 15 y) and 38 boys (range: 9 to 17 y) were included. Following multivariate analyses, 5 of the original 14 hip radiographic parameters remained significant. The predictions made by the optimized Oxford model had greater accuracy and fewer outlier predictions (predictions > 1 y off from actual years from 90% of final height) than the demographics only and modified Oxford only models (P < 0.05 for all). The optimized Oxford model had greater prediction accuracy than the demographics+modified Oxford model, but similar rates of outlier predictions (P = 0.903). No differences in mean prediction accuracy or rate of outlier predictions were observed between the optimized Oxford and the demographics+GP model (P > 0.05). Conclusion: High precision in skeletal maturity estimation can be achieved by using chronological age, sex, and 5 hip radiographic parameters. Clinical Relevance: We have developed a skeletal maturity system that utilizes anteroposterior hip radiographs and performs as accurately as GP.

Using Skeletal Maturity in Pediatric Orthopaedics: A Primer

“…Please refer to the supplemental materials for in-depth instruction and examples of how to use this skeletal maturity system. Reprinted with permission from Furdock et al19 Copyright Wolters Kluwer Health, Inc, Philadelphia, PA. All permission requests for this image should be made to the copyright holder.…”

“…An advantage of these systems is that the skeletal maturity output can be applied to a broad range of clinical questions (eg, predicting ultimate height, predicting ultimate lower extremity length). Disadvantages of these systems include the need to learn to evaluate multiple parameters and the longer time some of these systems take to implement for each patient, typically 1 to 2 minutes, 6,19 although even longer in the case of Tanner Whitehouse.…”

The Optimized Oxford Hip Skeletal Maturity System Proves Resilient to Rotational Variation

“…We evaluated our simulated radiographs using the methodology as described by Furdock et al, 11 (Table 1) and we used the following equations to estimate bone age (Table 2).…”

Estimating Skeletal Maturity Using Wrist Radiographs During Preadolescence: The Epiphyseal:Metaphyseal Ratio

“…Sanders et al7 recently established that the CA at which a child reaches 90% of final height (90% FH) correlates very well with the PHV. In addition, skeletal maturity systems developed using the 90% FH standard have had encouraging performance 11,12. When skeletal maturity is evaluated in terms of years before or after 90% FH or PHV, it can easily be converted to a skeletal age by adding the mean age of reaching 90% FH.…”

“…In addition, skeletal maturity systems developed using the 90% FH standard have had encouraging performance. 11,12 When skeletal maturity is evaluated in terms of years before or after 90% FH or PHV, it can easily be converted to a skeletal age by adding the mean age of reaching 90% FH.…”