Abstract
No doubt that revision TKR is a challenging procedure. This procedure may be divided into three steps. First, a careful clinical examination is needed to assess range of motion, stiffness and possible difficulty in exposing and extracting the prosthesis. Second, an examination of joint stability is needed. Finally, radiographs should be evaluated for any bone deficiency that may require bone grafting or special prosthesis.
Exposure approaches may change in cases when second stage implantation is performed when an infected total knee replacement exists and when a cement spacer is used. In the cases when the cement spacer is left in place for a longer period of time, stiffness is much more prominent and therefore exposure may be even more difficult.
Subvastus and midvastus approaches are not suitable for this kind of revision. Usually in revision of total knee replacement or after cement spacer procedures, a larger exposure with the use of either snip incision, or osteotomy of the tibial tuberosity, or VY exposure is required. There are some cases where one can perform revision total knee without the extra exposure mentioned.
In revising total knee replacement, it is imperative that the joint line be restored to its original position. There are a few techniques that can be used to achieve this task by using a few landmarks. They include:
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The residue of the menisci.
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The distance measured from the medial epicondyle to the joint surface.
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The distance measured from the head of the fibula to the original joint surface.
This can be done by comparing the other non-operated knee too.
The decision to which kind of prosthesis to use depends on the amount of bone loss and the injury to the surrounding structures and ligaments. One should be prepared for all options during surgery, in other words, using constrain or unconstraint prosthesis in the same patients. This depends solely on the findings during surgery.
In our hospital, we have used all the exposure approaches of the knee in revision surgery. We prefer the snip excision in the first stage, and if this is not sufficient then a tibial tuberosity osteotomy is preferred to the VY incision of the quadriceps mechanism. We found that using the meniscal residue is a very useful landmark for the joint line and we use it constantly.
The abstracts were prepared by Orah Naor. Correspondence should be addressed to him at the Israel Orthopaedic Association, PO Box 7845, Haifa 31074, Israel.
