Airplanes are usually staffed with medics to provide medical help in an emergency. These medics are usually trained and certified by the airline and the Civil Aviation Authority and hold the appropriate medical certificates.
However, in the real world, broken arm airplanes are not usually staffed with doctors. This is because physicians typically require specific medical equipment and techniques to handle complex medical situations that may not be available on an airplane. Additionally, doctors usually need more time and space on an airplane to deal with cases, and this can have an impact on flight operations.
As a result, in the real world, broken-arm airplanes are not usually staffed with doctors.