Early-Onset Perthes Disease in Patients Under 4 Years of Age: Natural Disease History, Radiographic Findings, and Prognostic Factors

Jaime Garcia-Fernandez; Juan Carlos Abril; Paloma Manzarbeitia-Arroba

doi:10.1097/BPO.0000000000003060

Early-Onset Perthes Disease in Patients Under 4 Years of Age: Natural Disease History, Radiographic Findings, and Prognostic Factors

J Pediatr Orthop. 2025 Jul 21. doi: 10.1097/BPO.0000000000003060. Online ahead of print.

Authors

Jaime Garcia-Fernandez¹, Juan Carlos Abril^{1

2}, Paloma Manzarbeitia-Arroba¹

Affiliations

¹ Department of Orthopaedic, Hospital Infantil Universitario Niño Jesús.
² Hospital Ruber Internacional, Madrid, Spain.

PMID: 40689860
DOI: 10.1097/BPO.0000000000003060

Abstract

Introduction: Early-onset Legg-Calvé-Perthes disease (LCPD) is commonly associated with favorable long-term outcomes; however, this is not guaranteed, as ~30% of these cases eventually develop poor outcomes. Identifying hips with poor prognostic indicators at an early age is crucial to guide appropriate surgical management. This study aims to describe the natural history of LCPD in patients diagnosed before the age of 4 and evaluate the correlation between radiographic findings and final outcomes.

Methods: All patients with LCPD onset before the age of 4 who followed a natural progression were included in this study. Serial radiographs were analyzed until skeletal maturity. Herring classification for femoral head collapse was assessed, alongside the collapse index (Co-index), defined as the degree of femoral head collapse relative to the contralateral healthy hip. Additional radiographic measurements analyzed included Reimer's migration index (RMI), the ellipsoidal index, the intraphyseal angle, and the presence of a double ossification nucleus. The correlation between these radiographic findings and final outcomes, as determined by the Stulberg classification and the sphericity deviation score (SDS), was evaluated.

Results: Of the 142 hips analyzed in 104 patients, 36% progressed to Stulberg grades III to V, with a mean SDS of 40.0. The entire cohort included 16 Herring A hips, 88 Herring B hips, and 38 Herring C hips, with a mean Co-index was 11.7% (range: 0% to 36%) and mean RMI of 16.2% (±8.35%). Final femoral head asphericity followed a consistent process of ovalization, characterized by the presence of physeal angulation (79.5%), a double ossification nucleus (89%), and a progressive increase in the ellipsoidal index (1±0.89) in hips with Stulberg grades III to V.

Conclusions: Early-onset LCPD does not guarantee favorable long-term outcomes, with one-third of cases resulting in final femoral head asphericity. This asphericity can be predicted by the progressive development of the ovalization process.

Keywords: Legg-Calve-Perthes disease; early-onset Perthes disease; ellipsoidal process.