fracture

Making ghusal with a fractured arm

Q: I am a 26 years old male. My right hand has got fractured and with plaster of Paris... Due to it I cannot use it and can't remove my upper clothes (shirt, etc.). I can go to the washroom on my own but I can't take a bath due to the injury. However I can only perform wudu (with masah on injured hand) and can wash lower part of my body i.e. legs and face and head. What is the ruling if ghusal gets obligatory upon me.... Should I make tayammum instead of ghusal or washing lower part of body, face and head and wet hand on upper body will suffice?