Coverage of Femoral Head at Weight-Bearing Interface of the Hip Joint in Children: An MRI Analysis

Objective: To analyze the features of coverage of femoral head at weight-bearing interface of the hip joints in children. Material and Methods: MRI scans of the hips were performed in 95 normal children aged from 1 to 8 years. Radial scans of the hip joints were performed using FFE sequence. Review the morphological features of weight-bearing interface of the acetabulum and the femoral head. Total covering angle (TCA), acetabular covering angle (ACA) and labral covering angle (LCA) were measured, inter-group comparison and correlation analysis were done. Result: The acetabulum and the femoral head had congruent articulating surface at each weight-bearing position. There was no statistical TCA difference at each position. Average ACA increased, while average LCA decreased from anterior to posterior. TCA correlated with LCA, ACA negatively correlated with LCA. Conclusion: TCA is a good index in indicating stability of the hip joint. Cartilage ossifies slower at posterior than anterior positions. Cartilage acetabulum and the labrum serve as complementary structures that contribute in total stabilizing of the hip joint in development.