Madelung's deformity is defined as a marked bowing of the radial shaft associated with increased interosseous space and dorsal distal radioulnar joint subluxation. 
It is due to an early closure or defect of the ulnar third of the radial physis. 

In 50-60% of cases, it can be bilateral. It is associated with rare congenital deformities such as Turner's syndrome, gonadal dysgenesis, achondroplasia, Ollier's disease, and Leri-Weill dyschondrosteosis. 

Surgical options include:

• radial epiphysiodesis
• radial corrective osteotomy
• radial physiolysis
• ulnar epiphysiodesis
• distal ulnar excision
• ulnar shortening osteotomy