Hi there!
You could go in for any exercises that don’t put extra strain on the knee to cause discomfort. Too little or too less motion around the joint is not desired. Activities like swimming, running, aerobics, yoga etc would fit into the criteria. Activities like biking need to be started gradually and one may increase the workload over a period of time. Care should be taken to exercise within comfortable limits. Excessive exercise may traumatize the joint which may lead to further worsening. On the other hand, immobility may lead to joint stiffness and disuse atrophy, further complicating the condition as well.
Hope this information was useful.
Take care!
I actuallly had surgery for my meniscus on my right knee. When rehabilitating I did a lot of exercise on the bike. It keeps you active and doesn't add a lot of pressure. The weight loss alone will help dramatically with the pressure. As I have put weight on I can deffinately feel the difference especially after I run.