ACL

I tore my ACL 5 years ago, but it still hasn't been the same since then.....I played four yrs in college and i play basketball overseas now....I rehabbed a lot in college but my quad never same to build back up like the one on my other leg...My knee bothers me sometime with pain but then eventually goes away once i warm up a little. But why does it not have full range of motion yet and as strong as it should be??