Knee cancer surgery. Artwork showing an early stage in the surgical treatment of a knee cancer using a Modular Universal Tumour And Revision System (MUTARS) interim prosthesis. The cancer is at the base of the femur (thigh bone) at upper left. Here, the internal muscle, bone and fat layers are shown, along with the blood vessels (red and blue) and nerves (yellow). The dotted lines show where incisions will be made to cut through tissues that will be folded back to allow access to the cancerous bone so it can be removed. At upper right, the inset shows a bone saw being used on the patella (knee cap).