Of course (speaking from personal experience here!) you gotta watch the nutrition too...JUST as important for burning off that stubborn thigh fat - that's most women's primary fat repository - the oldest, most established fat resides there at least for many of us ladies...
i have both horrible knees and a wickedly bad lower back. you would never catch me doing squats or lunges......... however i do leg presses, making sure that my lower back is very well supported and that my knees NEVER lock.
you can wrap your knees a bit for the leg presses, but i've found that if i do them by following the above advice i never have problems with my knees.