I did not have any known trauma, but my knee kept hurting after running and tennis. Along the way, I have had three injections. They have helped, and I have gradually improved as I exercise. The knee will never be perfect. It's now at about 80%, and I still feel pain, and there is some lack of strength. However, I don't believe I will need a surgical repair. A friend told me it would take a year to feel "somewhat normal." It has taken at least a year.