Do a small needle knife operation. No anesthesia. Does it hurt? How painful it is. What about using anesthetic? It's the inside of the knee. Said it was a muscle strain. Will it leave a scar?

It will hurt a little if you don't take anesthetic. If the surgeon pierces the skin quickly enough, it shouldn't hurt. Muscle strain includes muscle contracture, adhesion and scar, and the contracture, adhesion and scar of relaxation and peeling pain point can be treated immediately. The small needle knife only has a cut of about 1 mm, and there will be no scar. Moreover, scar is the therapeutic specialty of small needle knife. What are you afraid of?