Hook of hamate vascularity: vulnerability to osteonecrosis and nonunion.

A clinical impression of avascular changes in the hook of the hamate after fracture led to this study of the pattern and size of the hamate hook vascular foramina. It appears that vessels enter the hamate hook at primarily two sites. The radial base foramina are large and always present, while the ulnar tip foramina are small and absent in 29% of specimens. In these hamates, fracture at the hook base could potentially compromise blood supply to the hook fragment, and this may be a factor in hamate hook nonunion.