ABSTRACT
BACKGROUND: Within the lateral pillar classification of the Legg-Calve-Perthes (LCP) disease, hips seem quite variable in the pattern of fragmentation as seen in radiographs. The purpose of this study was to determine: if it is possible to reliably subdivide the lateral pillar groups into femoral head fragmentation patterns, and if such a subdivision of the lateral pillar groupings is clinically useful in managing LCP disease. METHODS: Two hundred and ninety-three anteroposterior radiographs taken at the maximal fragmentation stage (189 lateral pillar B, 57 B/C border, and 47 C hips; mean bone/chronologic age at the time of first visit, 6.2/7.9 years) and at skeletal maturity (mean age, 16.6 years) were analyzed. We distinguished 3 fragmentation patterns in each pillar group based on the region of major involvement. We tested the inter- and intraobserver reliability of our classification system and analyzed the relationships between the fragmentation patterns and the Stulberg outcomes as well as other factors such as surgical treatment and age. RESULTS: Inter- and intraobserver consistency in fragmentation pattern assignments was found to be substantial to excellent. A statistically significant trend (p = 0.001) in the proportion of Stulberg III or IV outcomes in comparison with Stulberg I and II was only found for the different fragmentation patterns in our lateral pillar B patients: fragmentation patterns having mainly lateral-central necrosis led to poor outcomes. No significant association was found between fragmentation patterns and Stulberg outcomes in pillar groups B/C border and C. CONCLUSIONS: Our results are consistent with the lateral pillar classification itself. Therefore, fragmentation patterns in each lateral pillar classification did not provide clinical usefulness in the management of LCP disease.