Two Stage Revision Surgery For Total Knee Replacement
Why Do You Need A Two Stage Revision?
Knee revision surgery is usually required when the replacement wears out - either through component wear or loosening. This is a common procedure and is usually very successful in restoring function. A Two Stage Revision is a different operation that is sometimes required because of infection.
Infection is an unfortunate complication of knee replacement surgery. Although rare, it occurs in around 1 - 2% of cases depending on the hospital.There are also different degrees of infection.
Firstly, there is a superficial wound infection that remains isolated at the surface. These often respond well to antibiotics and may not increase the length of hospital stay.
The much more serious type of infection is a deep infection at the level of the prosthesis. It often becomes impossible to treat these infections with antibiotics. As long as the metal remains the infection remains.
The treatment for this is drastic and is known as a Two Stage Revision.
StageOne of a Two Stage Knee Replacement Revision
The first stage is the removal of the knee prosthesis. The "joint" is then washed out and any non-viable tissue removed (known as debridement). Joint is in quotation marks here because it is no longer a true joint. When the replacement was originally put in, the ends of
the bone were removed to shape the knee for the prosthesis. At this point there is nothing to hold the bones apart to maintain the normal leg length. This is important to prevent the soft tissues from contracting and causing significant problems in the future. This issue is solved by inserting a spacer into the joint.
The spacer can be either pre-made or shaped out of bone cement by the surgeon. Once the joint is washed out, debrided and the spacer is in place, the wound is closed and antibiotic treatment continues.
The knee needs to be kept immobilized in a fully extended position so it is fixed with a splint or cast. As there is no joint surface inside the knee, no weight is to be taken through that leg so crutches or a walking frame are required.
Antibiotic treatment continues over the coming months with periodic blood tests to measure how the fight against the infection is progressing. When the blood tests suggest that the infection has been resolved, it is time for stage two. It is not uncommon for Stage One to take between three and six months.
Stage Two of a Two Stage Knee Replacement Revision
Stage two is inserting a new knee replacement. This is not as easy as the original operation as there has often been more bone and soft tissue loss. The operation usually take much longer than the original and the same complication and risks are evident. There is the chance of another infection. There is a chance the original infection was not completely cleared and may return.
The rehabilitation is also much more difficult. Because the knee was immobilized for months while the infection was cleared, it is extremely stiff and there are soft tissue contractures. After a normal knee replacement, the goal for knee flexion is for at least 90 degrees of bending. It is extremely unlikely a knee will bend this far after a two stage revision.Stiffness is likely to be a permanent complication and some people are left with a knee that only bends a small amount. There has also been a lot of muscle wasting leaving the leg very weak from lack of use. Rebuilding this muscle bulk takes months or even years.
When Do You Have A Two Stage Revision?
When you have to.
A Two Stage Revision is a salvage operation. It is not done by choice but when the situation demands it. It requires two large operations, months of antibiotic treatment and a significant period of disability hopping on crutches or a frame.
A Two Stage Revision is a necessary response to a serious situation. It is unfortunate that they are required but deep joint infections are a fact of life and are likely to remain so in the future.
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Other Types of Surgery For Knee Osteoarthritis
- High Tibial Osteotomy
A High Tibial Osteotomy is a common precursor to total knee replacement. It is used to buy time for people too young for total joint replacement.