Smith Machine Squats
Before you give up on squats totally, try doing them on a Smith Machine and see if that has any different effect on you. By having the weight being balanced and guided for you with the side rails, you can really get a good workout on your thighs and not have to be concerned with some of the other discomforts that come with regular squats.
If you can’t perform regular or Smith Machine squats, then a great alternative would be hack squats. The 45-degree angle of these will allow you to keep your knees very slightly bent at the top position, keeping the tension square on your thighs. Also keep your head and back on the pads and you should go down until your hamstrings are just below the parallel mark with the floor. You’ll know when you are low enough by taking a quick peek to check if your knees and toes are lined up together.
Bulgarian Split Squat
The Bulgarian split squat is similar to a lunge in some ways but with a much higher difficulty level due to the back leg being on a lift and using just your toes to balance it. You probably have seen people using a bench for this, but that is a little too high and you are better off using a shorter stanchion – no more than six inches. When the elevation is too high, it will compromise your range of motion and balancing ability. Line up your knee and foot on the front leg as a guide to help keep your body straight as you go up and down.