Introduction: Abnormal longitudinal growth in the early stage of puberty has been identified and thought to contribute to the development of adolescent idiopathic scoliosis (AIS). This phenotype of AIS was suggested to be caused by abnormal endochondral ossification but the histological evidence is still lacking.
Objectives: To confirm the abnormal endochondral ossification in AIS by histomorphometric study on the iliac cartilage from patients with AIS and control subjects at early and late stage of puberty.
Materials and Methods: Fourteen patients with AIS and nine control subjects were recruited and grouped according to the Risser sign(table 1). Iliac cartilage biopsies harvested intra-operatively were treated with standard tissue processes for paraffin embedding. Sections vertical to the calcification layer were stained with Heametoxylin and Eosin. The height of hypertrophic zone, the area and number of chondrocytes in cell-nest and the number of chondrocytes in proliferative zone were analyzed on the captured images of sections with Image-Pro Plus software.
Results: In Risser grade 0 group, significantly higher hypertrophic zone (P>0.05), larger cell-nest area and number of cells(P<0.05)was found in iliac cartilages from AIS patients. In contrast, there were no significant differences between the AIS patients and the normal with Risser grade 2.
Conclusion: Activated endochondral ossification was shown in AIS patients with Risser grade 0 but not in Risser grade 2. These indicated an abnormal endochondral ossification in AIS at the early stage of puberty.
Significance: The activated endochondral ossification in AIS observed at the early stage of puberty may contribute to the enhanced longitudinal growth.