Complex sentence: Prior to beginning development, Jarvis injured his right hand in an automobile accident--his hand was still in a cast when he returned to work, which prevented him from using a traditional joystick with a button.
Split into simpler sentences: Prior to beginning development, Jarvis injured his right hand in an automobile accident. Upon returning to work, Jarvis's right hand was still in a cast, which prevented him from using a traditional joystick with a button.