Will a pinched nerve in the back cause pain and swelling in the knee?

Yes: Is not uncommon for people who have back problems to also have knee and hip problems since arthritis is a systemic disease frequently. Your back pain may have offset your gate and irritated your kn ee cause swelling of the knee. However, it is not uncommon for people with herniated discs or back problems to experience episodes of generalized swelling of one or both lower extremities. Sinceback problems are neurologic in nature the homeostasis of the circulatory system can be affected. Of course there's also concern for reflex sympathetic dystrophy. We would need specific information on your physical exam and history. We would combine this with imaging studies to get a diagnosis. I would also start with an x-ray of the affected me.

Knee and spine: No but low back related weakness and proprioception problems around the knee joint can exaggerate and accelerate the wear and tear that a knee endures, and sometimes is a fundamental aggravating, causative factor.