I have extreme pain in my knees. walking they swell and sometimes buckle from walking?

Knee pain: Sounds like you have at least a cartilage tear recommend you see orthopaedic surgeon for evaluation.

Arthritis: Osteoarthritis is the most common type of knee arthritis. Also called wear-and-tear arthritis or degenerative joint disease, osteoarthritis is characterized by progressive wearing away of the cartilage of the joint. As the protective cartilage is worn away by knee arthritis, bare bone is exposed within the joint. Check it out.