It is a congenital subluxation or dislocation of the ulna's distal end, due to malformation of the bones. Sometimes, minor abnormalities of other bone structures, often caused by disease or injury, such as a fracture of the distal end of the radius with upward displacement of the distal fragment. The<unk>  varies in degree from a slight protrusion of the lower end of the ulna, to complete dislocation of the inferior radio-ulnar joint with marked ulnar deviation of the hand. Severe<unk> es are associated with congenital absence or hypoplasia of the radius. The male:female rate of this disorder is 1:4. The incidence is unknown, and there is no described racial predominance. Even though<unk>  is considered a congenital disorder, symptoms sometimes aren't seen until adulthood. In most cases, symptoms find their onset during midchildhood. At this age, the relatively slower growth of the ulnar and palmar part of the radius, leads to an increasingly progressive<unk> . Pain and<unk>  are the main symptoms patients present with. Typical clinical presentation consists of a short forearm, anterior-ulnar bow of the radius and a forward subluxation of the hand on the forearm. As mentioned before, the severity of the disorder varies greatly, which also leads to a spectrum of presentation.
Madelung's deformity
Boutonniere deformity
Sprengel's deformity
Tailor's bunion
Freiberg disease
Haff disease
Butcher's wart
Dupuytren's contracture