Knee surgery anaesthetic. Liquid anaesthetic being injected into a patient's knee using a syringe. The anaesthetic will numb the area to be operated on, allowing the arthroscopic probe (lighted tip seen below syringe) to be inserted into the knee with minimal pain. Localised anaesthetic like this numbs a specific area, rather than the whole body, as in a general anaesthetic. The arthroscope will send pictures back to the surgeons, allowing them to assess conditions inside the knee. This patient has rheumatoid arthritis of the knee. Rheumatoid arthritis is an auto-immune condition where the body's own immune system attacks the joints and causes damage and inflammation. Photographed in the UK.