Final answer:
The main complication of a distal radius and ulna physis fracture is growth disturbance, which can cause deformity or length differences in the limb. Colles' fractures can also lead to malunion, where the wrist heals in a deformed position.
Step-by-step explanation:
The most common complication following a fracture of the distal radius and ulna physis is growth disturbance leading to a deformity or length discrepancy in the affected limb. In children, the injury involves the growth plate (physis) and can disrupt the growth potential, resulting in angular deformities or unequal limb lengths as the child grows. Another complication specifically associated with Colles' fracture is the potential for malunion, with the wrist healing in a disfigured "dinner fork" configuration due to the characteristic displacement of the distal fragment of the radius.
A Colles fracture of the distal radius is the most common complication of a fracture of the distal radius and ulna physis. This type of fracture involves a complete transverse fracture across the distal radius that drives the separated distal fragment of the radius posteriorly and superiorly. It results in a characteristic 'dinner fork' bend of the forearm just above the wrist due to the posterior displacement of the hand.