Joint Supplement that Works!

My grandparents have been married for 50 years. I am very proud and thankful to have them as my grandparents. I have lived with them since I was in high school until I got married. I have witnessed how they struggle waking up in the morning with an achy joints. My grandmother sometimes can't walk because of her knees. I am thinking of getting my grandparents a joint supplement that will actually relieve achy joints.