How do you know the difference between a full and partial ACL tear?

Acl. The best non operative way to tell the difference is by a MRI evaluation.
Examination. A full acl tear is unable resist rotational and anterior (frontal) forces that we can test for during a physical exam. A partial acl tear should feel the same as a normal acl or a touch looser. Whether to reconstruct an acl should not be based on an MRI finding. It should be based on individual activity level and demands. It should be tailored to your individual knee and situation.