Failure of differentiation: Part II (arthrogryposis, camptodactyly, clinodactyly, madelung deformity, trigger finger, and trigger thumb).

The term "failure of differentiation" describes the phenotypes of a large number of otherwise unrelated conditions. The six conditions described here (arthrogryposis, camptodactyly, clinodactyly, Madelung deformity, trigger finger, and trigger thumb) are believed to occur because various structures failed to differentiate normally; however, they have neither common features nor a common cause. We have included information about the history and diagnosis of these conditions, the cause (if known), and the current concepts of treatment and expected outcomes.