Classification and surgical treatment of the angled thumb

Angular deformity of the thumb is most often caused by a delta phalanx or a longitudinally bracheted diaphysis in a triphalangeal thumb. In some angled thumb, however, triangular-shaped secondary ossification center can cause the deformity, which can be called “abnormal triangular epiphysis” of the thumb. A few clinicians have reported this entity, but they do that utilise this term instead classifying class it as a subgroup of delta bone within a triphalangeal thumb.