Clinodactyly is a curving of the fifth digit (the little finger) toward the fourth digit (the ring finger). Sometimes called fifth finger clinodactyly to distinguish it from similar curving of other finger or toes. Clinodactyly is a minor congenital birth defect. In clinodactyly the middle bone in the fifth finger is underdeveloped and, instead of being rectangular, is wedge- shaped. No treatment is required.