Knee arthroscopy is a surgical procedure that can diagnose and treat problems in the knee joint. A tiny camera is inserted into the knee to investigate and, if necessary, correct the issue. Arthroscopy diagnoses problems such as a torn meniscus, swollen synovium (the lining in the joint) or a misaligned patella (kneecap). It can also repair the ligaments of the joint. A doctor may recommend knee arthroscopy for those experiencing knee pain. It is most common during the treatment of sports injuries.