Risk of Pulmonary Embolism After Total Knee Replacement

Sometimes patients need both knees replaced because of severe arthritis. If both knees are done at the same time, the operation is called a simultaneous bilateral total knee replacement (TKR). If the patient has one knee done at a time, then it's called a staged procedure.

The question remains, should both knees be done at the same time (simultaneous)? Or is it better to do the first knee, wait until the patient has recovered, and then do the second knee (staged)?

In this report, the results of 122,385 Medicare patients who had a TKR in 2000 are reviewed. Age, gender, race, and whether the TKR was simultaneous or staged were tallied up. The risk of blood clots to the lung called pulmonary embolism was calculated for both the simultaneous and the staged procedures.

The researchers also looked at where the operations were done and who did them. Total number of TKRs for each geographic area of the U.S., hospital, and surgeon were added up and reported.

The authors report that most of the patients (78.5 per cent) had a unilateral (single) TKR. When a simultaneous or staged TKR was done, it was usually in a high-volume hospital by a high-volume surgeon. Simultaneous TKRs was most likely in white men of higher economic status.

The risk of pulmonary embolism in the first three months after surgery was greatest for patients having a staged operation. However the results must be viewed with caution. If a patient was planning to have both knees replaced in a staged operation but had a clot after the first operation, then the second TKR was cancelled. This factor could make it look like the rate of embolism is higher with unilateral TKRs.

Data from this study may be used to make policy decisions. For example, programs may want to shift patients from low to high-volume centers for simultaneous TKRs. Such a move may lower the overall risk of pulmonary embolism.