Incidence and ossification of sesamoid bones in the hands and feet: a radiographic study in an Arab population.

The incidence and ossification of sesamoid bones in the hands and feet were studied in 922 radiographs (400 hands and 522 feet) in an Arab population from Bahrain, 5-83 years of age and consisting of 549 adults (393 men and 156 women) and 373 children (286 boys and 97 girls). All radiographs of the hand and foot in the adult population showed two sesamoid bones in the thumb metacarpophalangeal (MCP) joint and in the hallucal metatarsophalangeal (MTP) joint, respectively. Only 2.3% and 1.5% of hands showed sesamoids at the MCP joints of the middle and ring fingers respectively compared to a reported incidence of 7.1% for each digit in Caucasians. The incidence of sesamoids in the MTP joints of third and fourth toes (0.6% each) and inferior to the hallucal interphalangeal joint (3.1%) is probably the lowest reported so far in the literature. In the hands, ossification commenced first in the thumb sesamoids, at the age of 10 years in females and 11 years in males and was completed by the age of 13 and 14 years, respectively. In the feet, ossification began first in the hallucal sesamoids at the age of 8 years in females and 9 years in males and was completed by the age of 10 years in both sexes. The incidence and ossification of sesamoids in the hands and feet in the Arab population from Bahrain seem to differ considerably from reports in other populations. The clinical significance of our findings is discussed.