Karate Kid Finger appears as numbness over the dorsoulnar aspect of the little finger, i.e. the two segments of the finger above the nail.  There may be a hot spot near the middle joint – the proximal interphalangeal joint on the side of the finger. 

Karate Kid Finger is due to karate chops with flawed technique or to overuse, causing contusion and scarring of the nerve serving the skin over the dorsomedial aspect of the distal and middle phalanges of the little finger. 

Rest, anti-inflammatory medications, as well as moderation and technique correction usually suffice. Sometimes surgery is necessary to microscopically free the nerve of scar tissue.