MODEL RELEASED. Knee arthroscopy. Image 2 of 2. Surgeon inserting an arthroscope through an intrument in 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 pouring out of the instrument is sterile liquid injected into the knee to improve the image. Knee arthroscopy allows the 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. To see an image of the instrument being inserted, see M440/227.