I do appreciate your concerns, but knee braces are going to make it difficult to use clutch and breaks. Also, it may not be advisable to take up car racing after surgery. However, please discuss this with your specialist at your next appointment. Take care!
The medical advice given should not be considered a substitute for medical care provided by a doctor who can examine you. The advice may not be completely correct for you as the doctor cannot examine you and does not know your complete medical history. Hence this reply to your post should only be considered as a guiding line and you must consult your doctor at the earliest for your medical problem.