Senri-
I wouldn't recommend doing leg extensions. They'll likely only aggravate your problem. Leg extensions place huge shearing forces on the knee joint and can actually be far more injurious than squatting or other leg exercises. Also, isolation is rarely ever the best rehab option.
Davan-
Pelvic stability is a term commonly used in the fitness realm with no clear definition. The pelvis can be stabilized by many means some of which could actually be disadvantageous to sport performance.
ELITETRACK Founder