Primary total knee arthroplasty enjoys outstanding success at 10 and 15-year follow-ups. However, knee replacements will eventually wear out and fail and need revision. The most common cause of failure of knee replacement in the first few years are infection and instability of the knee. In the long run, the primary cause of failure of knee replacements is wear of the polyethelene and loosening of the components from bone. Each one of these causes of failure presents different challenges to the surgeon at the time of revision. There are several problems associated with revision surgery. First, the exposure is more challenging then in the first time surgery. Implant removed can at times be difficult resulting in some loss of bone. Reconstruction of bony defects that occur as a result of the wear or the loosening process can also prove challenging. We have several methods for making up bone loss and these include, use of metal augments that attach to the revision implants, use of bone graft either from the patient or more commonly from bone donors, and use of special metal sleeves or cones that will fill in the defects. At the time of revision surgery the surgeon will assess the defects and make a decision as how best to replace the missing bone and then build an implant that fits the knee, often using longer stems to augment fixation in the thigh bone and shin bone. Once stable reconstruction of the joint occurs rehabilitation of the knee begins. The recovery from revision knee replacement is often a bit more challenging, due to the soft tissue and bony defects and must be individualized for each particular patient. An increasingly smaller number of surgeons are taking care of the increasingly more difficult revision cases and this may prove to be a concern in the future as there will be fewer surgeons available to take care of an increasing number of revision knee replacements.