Camptodactyly is a medical condition that causes one or more fingers to be permanently bent. It involves fixed flexion deformity of the proximal interphalangeal joints. The fifth finger is always affected. Camptodactyly can be caused by a genetic disorder. In that case, it is an autosomal dominant trait that is known for its incomplete genetic expressivity. This means that when a person has the genes for it, the condition may appear in both hands, one, or neither.