MODEL RELEASED. Knee arthroscopy. Surgeon removing an arthroscope from a patient's knee joint. The arthroscope (narrow telescope) is used to view inside the joint. It contains optic fibres that transmit an image of the joint onto a video screen. The fluid escaping the incision in the knee is sterile liquid that was injected into the knee joint to improve the image. Knee arthroscopy allows diagnosis of knee problems such as arthritis and inflammation and can be used to repair damaged tissue and cartilage. During the procedure, small tissue samples may be taken (biopsies), which can help diagnose infections.