Fracture of the Humerus at Its Weak Spot

The reconstructed CT scan of the right shoulder exemplifies the pathogenesis of a fracture along the weak part of the bone where the shaft (diaphysis) meets the metaphysis (neck) indicated by a green arrow. The most important aspect to appreciate is the manner in which the strong cortical (compact bone tapers as it progresses from the middle of the diaphysis to the junction of the diaphysis and metaphysis also marked by the arrow. The spongy (trabeculated bone) resides in the epiphysis (red) and metaphysis (pink). The epiphyseal line is the region of the epiphyseal plate which was active during bone growth but which becomes a mere line in the adult bones.

Courtesy Philips Medical Systems and Ashley Davidoff MD 88367bc03.8s