Ossification of the calcaneus in the normal fetal foot and in clubfoot

The ossification of the fetal calcaneus was studied in a series of plastina ted sections of 44 normal feet and three clubfeet. The results documented a precise sequence of perichondral and endochondral ossification in the norm al calcaneus characterized by ossification grooves and associated cartilage canals. Within the clubfoot calcaneus, the coordination of perichondral an d endochondral ossification is disturbed, ossification grooves and associat ed cartilage canals are not found in regular positions, and the process of endochondral ossification obviously is disturbed. The findings in the clubf oot specimens point to grave irregularities of the extracellular matrix wit hin or outside the calcaneus.