Kirner's deformity. Juvenile spontaneous incurving of the terminal phalanx of the fifth finger.

Juvenile spontaneous incurving of the terminal phalanx of the fifth finger is extremely rare. The etiology is still uncertain; the combination of a primary epiphyseal disorder and tendon traction has been stressed. Peroperative biopsy has, apart from an epiphysiolysis, shown changes in accordance with osteochondritis dissecans.