A total knee replacement involves replacing the natural, damaged joint (as well as some tendons and ligaments, if required) with an artificial joint, which is fused to the bone on both sides and allows the joint to bend freely and painlessly. In most cases, a total knee revision can be expected to last around 15-20 years. As with many things in modern medicine, however, this is only an estimate and each individual patient will find that their experience with joint replacement is different. Ultimately, there are a variety of reasons why a prosthetic knee joint may fail, including:
- Mechanical loosening: the artificial joint begins to separate from the bone. This usually occurs in patients who were younger when the original surgery was conducted.
- Infection: an infected joint will become stiff and painful, and potentially loose as well.
- Bone fractures: If the bone fractures near the artificial joint, it may be necessary to replace the original prosthesis with a new one with longer stems that will fix the fractures like a metal pin.
- Instability: partial or complete dislocation of the artificial joint can cause unsteadiness, limited range of motion, and intense pain.
- Wear and breakage: over time, parts of the artificial joint may simply wear out and even break, requiring that either part or all of the implant be replaced. This is more likely in patients who engage in high-impact activities.
If you experience any of these problems, a revision total knee replacement may be required. During revision total knee replacement, the original prosthesis is removed and replaced with a new one. This procedure is more complex than a primary total knee revision and requires specialized tools and a skilled surgeon. For these reasons, it is critical that you select a surgeon who has extensive experience performing revision total knee replacements.
Procedure and Recovery
A revision total knee replacement typically occurs in two distinct phases. First, the surgeon will need to remove the existing prosthetic joint. Because the old implant has likely fused to the bones, some bone may also need to be removed as well. A new artificial joint made of either cobalt chrome or titanium is then cemented into place with the addition of stems for added stability of the already weakened bone. In some cases, it may be necessary to implant bone graft, moving bone from a donor site on the patient’s own body or more commonly using donated bone. This helps to create more bone surface for the new prosthesis. Because the bone is no longer the original shape, the surgeon must use a specialized prosthetic implant that has been tailored to match the bone structure of each individual patient. This prosthetic may also be longer to accommodate the loss of original bone structure. Ensuring that the new prosthesis accurately and precisely fits into the natural structure of the leg requires significant pre-operative planning, occasionally a pre-operative CT scan, specialized tools to alter the prosthetic device, as well as advanced technical skill on the part of the surgeon.
Recovery from a revision total knee revision is similar to recovery from a primary total knee revision. A hospital stay of several days is usually required, although most patients are encouraged to stand and walk as quickly as possible, even within hours of the procedure, to facilitate the process of bonding the new implant and growing new bone and lessen the likelihood of a blood clot forming. Regular physical therapy is usually recommended for several weeks after the procedure. Within several months, the majority of patients are able to resume normal, low-impact activities. It is important to note that a revision total knee implant is likely to last around 15-20 years, or longer, if appropriately taken care of and it is not meant to function like that of a primary implant.