A New Skeletal Maturity Methodology for Children With Legg-Calve-Perthes Disease.

Background: Legg-Calve-Perthes disease (LCPD) outcomes are largely determined by their age and maturity at onset. In LCPD, there is a known association with delayed skeletal maturity of up to 1.9 years in affected children based on maturity assessment with the Greulich and Pyle (GP) maturity atlas. The GP atlas is the standard for assessing bone age but requires obtaining a separate radiograph of the hand. A new methodology for assessing skeletal maturation in comparison to the GP bone age in children with LCPD was sought.

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. Patients were included if they had LCPD diagnosed on anteroposterior pelvis radiographs that included the contralateral hip who had bone age radiographs obtained at the time of presentation. Patients were excluded if they presented with bilateral LCPD, the contralateral hip was not visualized on their presenting radiographs, they lacked bone age radiographs at the time of presentation, or they presented outside the range for the Optimized Oxford system. A formula using the greater trochanteric height to femoral head diameter ratio and patient sex (GT+ Sex) for predicting GP bone age was developed. The GP and GT+ Sex bone ages were compared with the chronologic age (CA) to determine the mean discrepancy.

Results: Seventy-one patients were included (mean 9.5 ± 1.2 y at presentation, 42.2% females). Skeletal maturity assessment by the GP bone age method demonstrated a mean discrepancy of 1.4 years younger than CA (95% CI: 1.01-1.76 y). GT+ Sex bone age assessment demonstrated a mean discrepancy of 1.4 years younger than CA (95% CI: 1.03-1.75 y). The GP bone age was a mean of 0.00 years different than the GT+ Sex assessment bone age (95% CI: -0.3 to 0.3 y). The GT+ Sex assessment bone age correlated significantly with GP bone age ( R =0.89, P <0.0001). Male patients had a significantly younger GP bone age relative to CA compared with female patients (1.8 vs. 0.86 y, P = 0.02); however, there were fewer sex differences in the GT+ Sex assessment bone age relative to CA (male, 1.77 y younger vs. 1.12 y younger; P = 0.01).

Conclusions: The GT+ Sex skeletal maturity assessment system in children with LCPD significantly correlated with the GP bone age system when compared. The GT+ Sex assessment may provide an assessment of the true bone age in LCPD patients without the need for hand radiographic imaging studies.

Level of evidence: Level III-retrospective review and analysis.