jimmyhonda, (and also Lazer-LXXVII),
Muscular Dystrophy is a disease whose primary characteristic is weakness. That is, you cannot climb stairs, or get out of a chair. Also, many MD patients fall down a lot.
Muscle contractures (tight muscles), ARE a symptom sometimes, but contractures are different than muscle spasms and cramps at night. My Muscular Dystrophy is absolutely painless. Muscle contractures occur over months or years as the muscles shorten.
I'm not sure what's causing your uncomfortable cramps but fortunately I would not worry too much that it is muscular dystrophy. Osteoarthritis is a deteriorization of the bones and joints. My mother has it and keeps it in check. This, unlike MD, can be somewhat treated. If you don't mind me asking, how old are you?
Best of luck.
Mark