Hi there, Thanks for your query. From the brief details, it appears that you husband has been suffering from osteoarthritis, with acute pain and present problems precipitated by breaking off of a small piece of cartilage in the joint (which causes osteoarthritis). Other possibility is avulsion of a tendon around the knee joint. Get a CT scan of the knee to establish the exact cause. Rest to the knee joint, along with a short course of anti-inflammatory pain-killers, such as ibuprofen + paracetamol combination will help. Consult your doctor and apprise him of my opinion. I am certain that he agree with me, order required tests, and- based on the reports- will prescribe suitable treatment as advised. If you find my response helpful and informative, do not forget an “excellent” rating to my answer, to encourage all doctors- engaged in social service- to render sound advice to the FREE queries. Fond regards and have a nice day Dr. Rakesh Karanwal