Which of the following injuries is specifically associated with the thumb under stress?

The correct answer is Bennett's fracture, which is specifically associated with a fracture at the base of the first metacarpal bone, often leading to instability of the carpometacarpal (CMC) joint of the thumb. This type of fracture typically occurs as a result of trauma to the thumb, such as when the thumb is subjected to axial load or force while in a position of flexion or extension.

Bennett's fracture is characterized by both a fracture and a fracture-dislocation, which makes it a unique injury compared to other thumb-related injuries. This injury often requires careful assessment and management to ensure proper alignment and stability during the healing process.

In contrast, mallet finger refers to a tendon injury at the distal phalanx, causing an inability to extend the fingertip, but it is more associated with the fingers than the thumb specifically. Swan neck deformity is a chronic condition typically resulting from injuries or arthritis that lead to hyperextension at the proximal interphalangeal joint. Handlebar palsy refers to compression of the ulnar nerve due to prolonged pressure on the hand, often seen in cyclists, and does not directly involve a bone injury.

Thus, Bennett's fracture is uniquely tied to the mechanics and structure