Fractures of the hook of the hamate may be sustained in a fall, but more often occurs in sports such as tennis, baseball, and golf, in which a handle sharply impacts the proximal hypothenar palm. As with the scaphoid, these fractures are frequently missed initially, and may not be visible on standard x-rays. Also similar to the scaphoid, they are prone to nonunion and may result in secondary complications. The hook of the hamate is the point of attachment for hypothenar muscles, and when fractured through the base, these muscles alternately stress the fracture in different directions, pre-disposing to nonunion. The hook also functions as a trochlea for the flexor tendons of the small finger (Fig.40) Surface irregularities or chronic local inflammation can result in flexor tendon rupture, ulnar neuritis, and ulnar artery occlusion in Guyon's canal. Confirmation of this diagnosis may require special x-ray views of the hamate, including carpal tunnel view and 20 degree supinated oblique views, bone scan or CT scan. Standard treatment is excision of the hook fragment and smoothing the base to prevent future tendon chafing.