The incidence and structure of the fabella in a South African cadaver sample.

The fabella, a sesamoid bone located in the tendon of the lateral head of the gastrocnemius muscle, was dissected from 102 lower limbs of 51 cadavers of age range 40-95 years (mean, 75.5 ± 14.5 years). The incidence of this sesamoid was determined as were its dimensions and radiological and histological features. The fabella was present in 23.5% of individuals, and it was bilaterally located in 50% of cases. It had an equal likelihood of occurring in males or females (P = 0.60), and in either right or left lower limb (P = 1.0). The consistency of the fabella was mostly bony (72.2%), a variety predominantly seen in male subjects. The mean diameters were 9.98 ± 0.9 mm and 8.78 ± 1.23 mm in males and females, respectively, with a statistically significant difference of P = 0.033. Histologically, bony fabellae had a core of spongy bone surrounded by compact bone, whereas nonbony fabellae were characterized by fibrocartilage.