Micro-computed tomographic analysis of trabecular bone pattern in the juvenile distal femoral metaphysis

Throughout the juvenile period, the knee joint must accommodate several developmental milestones including weaning, crawling, sitting and the attainment of bipedal gait. These activities are related to the magnitude, direction and distribution of mechanical forces passing through the joint and are thought to contribute to the formation of specific trabecular bone signatures. This study aimed to investigate this trabecular bone architecture in the developing distal femur and relate this to the forces acting at key developmental milestones.

Micro-computed tomography was performed on 63 specimens within the prenatal to 7-year-old age range. Trabecular bone quantification was conducted in twenty-two volumes of interest (VOI) in the distal metaphysis. Four trabecular bone parameters were analysed within each VOI including; bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular separation (Tb.Sp) and trabecular number (Tb.N). Statistical analysis was performed to identify significant differences between different VOIs, and between different age groups.

Bone parameter values were similar between VOIs in subjects under 1 year old. A reduction of BV/TV during the first two years after birth was highlighted, with the lowest value found between 1 and 2 years old. The decreased BV/TV may be related to reduced mechanical stimulation, compared to the intra-uterine environment, and reduced nutritional supply after birth. Increased BV/TV was observed after 2 years. Significantly higher BV/TV, Tb.Th, Tb.N and lower Tb.Sp were found in sub-cortical VOIs compared to central VOIs.

Trabecular bone patterns were shown to reflect the forces associated with key developmental milestones.