No. Your parents making you do something you found boring is not abuse. The idea is to develop a habit of putting aside time to pray before going to bed.
Nobody can force you to pray, but you should sit quietly and respectfully during that time. It’s similar to dinner time. Just because you claim you aren’t hungry doesn’t give you the pass to go play Mario Bros. Your parents can’t physically force you to eat, but you still have to sit up at the table and participate in meal time. Similarly, the teacher can’t force you to read during silent reading time, but she can require you to remain in your seat quietly and hold the book right-side-up. Also, a mom can’t force a kid to pee, but she can require him to take the time to sit on the toilet for a minute and hopefully try to empty his bladder before a long car trip.
It was probably not right of your parents to make you kneel for the entire time if you were saying that it was painful. Kneeling is a good position for prayer, but it isn’t the only position. If it causes discomfort to the point that it distracts from the prayer, it’s best to choose another position. However, if your parents were dealing with kids who were being demonstratively disrespectful during prayer time, I could see insisting on a specific, appropriate posture. They probably should have put more thought into what posture is appropriate if you were complaining of pain in the knees, but it is often hard, when a child is being defiant, to guess what really is a serious complaint and what is just a fabricated excuse to not comply with the rules. Sometimes, when my daughter gets bored in Mass, she tries to be demonstrative about it by laying down in the pew. If she does, she is told that she has to sit up with her hands in her lap. This position should not be causing her any discomfort though. Your parents should have considered that the kneeling position was causing you discomfort and allowed you to sit up instead. Unless the Eucharist was exposed in your livingroom, there was no reason to require kneeling.