The radius and ulna bone provide the bony scaffold for the forearm. They allow the wrist and hand to be accurately suspended in space to perform tasks. Due to the shape of the radial head and the configuration of the joints joining the radius and ulna, they allow complete rotation of the hand and wrist.
Fractures occur due to a direct blow in sports, work or other mechanisms. They may occur in either bone, or often both are fractured. If both are fractured, then surgery is the best solution. Forearm stability is essentially provided by a ring construct, with the radius and ulna connected to each other by the proximal and distal radio-ulnar joints.
If the two bony parts of the ring are broken, it is near impossible to get enough stability back in the ring using merely a cast to hold and align the bones, hence surgery is required. If one of the bones alone are broken, then the ring must be broken in another place if it has been deformed, and either the proximal or distal radioulnar joints are disrupted or dislocated. For optimal recovery, the bone AND the joint needs to be reduced, hence surgery is required to accurately reduce and fix the fracture.
In select, minimally disrupted fractures, where the ‘ring’ hasn’t undergone significant deformation, the fracture may be managed in a cast only for 4-6 weeks.