If the knee injury and surgery occurred three years ago, by now you should be able to use the Elliptical machine, and dd do exercises that strengthen your quads, as bicycle and weights, trying always not to exceed your own capabilities and avoiding overuse. The movements that you are not allowed to do are those that imply excessive twisting, rotation and bending of the knees.
These Q&A’s are for educational purposes and should not be relied upon as a substitute for medical advice you may receive from your physician. If you have a medical emergency, please call 911. These answers do not constitute or initiate a patient/doctor relationship.