The labels describe when RUS began and how many arms are affected. They do not, by themselves, describe someone’s full range of movement or daily experience.
Some people are born with the condition (CRUS); others develop radioulnar synostosis after physical trauma. CRUS may be identified shortly after birth or later in childhood. Post-traumatic RUS can develop after a forearm fracture, surgery, or another injury.
RUS can affect both arms (bilateral) or one arm (unilateral). People with one affected arm may need fewer daily adaptations, while people with bilateral RUS can have different mobility in each arm. The practical effect depends on the position and extent of the fusion, not only the label.
Every person with RUS can have a different degree of fusion, position, mobility, pain, and need for adaptation. A diagnosis is a starting point, not a complete description of someone’s life.
