Greater Trochanter Height: A Quantitative Predictor of Skeletal Maturity

Skeletal Maturity in Legg-Calve-Perthes Disease: Significant Discrepancy Present Between the Hand and the Hip

BACKGROUND

The concept of delayed skeletal maturity in Legg-Calve-Perthes Disease (LCPD) has been well identified with the Greulich and Pyle (GP) atlas showing 1 to 2 years delay. Recently the optimized Oxford hip skeletal age (Optimized Oxford) system has been developed and shown to have similar accuracy as the GP atlas for assessing skeletal maturity. However, this system has not been used to assess skeletal maturity in LCPD.

METHODS

A retrospective review of a prospective, multicenter study of patients with LCPD treated from 1984 to 1991 and followed to skeletal maturity was performed. We identified all patients who had a left-hand radiograph at the time of presentation with an accompanying anteroposterior pelvis radiograph including the contralateral hip. Patients were excluded if their age at presentation fell outside the validated range for the Optimized Oxford system. GP atlas was used to determine bone age using left-hand radiographs and the nonaffected hip radiographs were used to calculate the Optimized Oxford bone age. Skeletal maturity indices were compared with chronological age (CA) to determine the discrepancy between methodologies.

RESULTS

A total of 71 patients met inclusion criteria (mean 9.5 ± 1.2 y at presentation, 42.2% females). The mean GP bone age was 1.4 years younger than CA (95% CI: 1.01-1.76 y), with the discrepancy being greater for boys than girls (1.8 vs 0.86 y, P = 0.02). The mean Optimized Oxford bone age was 0.31 years older than CA (95% CI: 0.24-0.38 y) and correlated significantly with CA ( R = 0.97, P < 0.001). There were no sex differences in the Optimized Oxford bone age relative to CA ( P = 0.32). The GP bone age was a mean of 1.7 years younger than the Optimized Oxford bone age (95% CI: 1.35-2.05 y).

CONCLUSION

Skeletal maturity assessment in children with LCPD varies according to the utilized maturity system. The Optimized Oxford bone age more closely mirrors the patient's CA and does not correlate with the GP bone age, which reveals a delayed maturation.

Using Skeletal Maturity in Pediatric Orthopaedics: A Primer

This article provides researchers with the background and guidance necessary to practically incorporate skeletal maturity estimation into any study of adolescents with imaging of the shoulder, elbow, hand, hip, knee, or foot. It also provides clinicians with a comprehensive, concise synopsis of systems that can be used to estimate skeletal maturity in clinical practice. In the article, we provide a relatively brief overview of each currently available skeletal maturity system that has been validated on a longitudinal dataset. The supplementary files include 2 PowerPoint files for each skeletal maturity system. The first PowerPoint file offers examples and instructions for using each radiographic system. The second PowerPoint file includes 20 graded radiographs that can be used for reliability analyses in the research setting. We have also developed a free mobile application available on the iOS and Android platforms named "What's the Skeletal Maturity?" that allows clinicians to rapidly estimate skeletal maturity on any patient using any commonly obtained orthopaedic radiograph.

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

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.