To create those ultimate thigh workouts you are working with potentially one of the biggest muscles in the leg, the thigh is involved in almost all the movements you make with your lower body to some extent and is very important when it comes to avoiding need pain.
Its crucial to get that your thigh workouts balanced as one of the main reasons why individuals suffer from knee pain is because their inner or outer thigh muscle is stronger than the other and this creates an off balance. Whatever side of the thigh is strongest will begin pulling the knee cap in that direction causing it to go off track so much that it may end up grinding against the bone or other ligaments.
The way your knee is built makes it designed to move along a specific movement pattern and when it is not doing this, trouble is abound.
When focusing on hip workouts for this region of the body it is important to really consider working it from a variety of angles so that you can target each of the quad muscles specifically. There are four main heads, the rectus femoris, the vastus lateralis, the vastus intermedius and then finally the vastus medialis. If all you ever performed was, say, simple leg extensions, you would be largely leaving out the vastus lateralis thus not really getting that effective of a workout. By include squats and lunges on the other hand, you would be targeting all areas and would increase leg strength to a much greater extent.
Additionally, you do not always need to use weight in order to improve the condition of this area of the body. Many plyometric exercises will work really well at improving the conditioning such as squat jumps, box jumps and burpees, all of which will not only improve strength but also improve muscular power.
So be sure that you do not leave this body part out of your training, especially if you have suffered from knee injuries in the past. It is critically important that you learn to include a wide variety of exercises as well so that your body keeps responding to the stimulus and so that you are not leaving any aspects of this muscle out.