Originally posted by: brikis98
A few questions:
1. Why do you want "bigger" legs? Aesthetics? Or do you actually want stronger legs?
2. Are you sure you are using proper squat technique? When squats are done correctly - with the heels firmly on the ground, the back locked in extension, and the hip joint going below the knee joint ("below parallel") - they are actually known to improve the health and strength of the knee joint.
Starting Strength discusses the safety and technique of the proper back squat.
Stronglifts also has a decent tutorial. It's certainly possible that your injury really does prevent you from squatting, but it may be worth trying some air squats (ie, just your body weight) with the correct technique to test it out.
3. It's worth remembering that there are also many variations of the squat: high bar, low bar, sumo stance, athletic stance, front squat, overhead squat, box squat, split squat, hack squat and single legged squat (pistol). Perhaps some of these will feel better for you than others.
Finally, if your injury really does prevent you from doing the squat and any of its variations, even with proper technique, there are other exercises you can try. There is no
real substitute for the squat, but doing something is better than nothing. Here are a few:
Deadlift
(Weighted) lunges
(Weighted) step-ups
Box jumps
Power clean
Power snatch