Having Both Knees Replaced at the Same Time: Pros and Cons

With today's improved technology in and out of the operating room, patients have the option of bilateral total knee replacement (TKR) at the same time. This can be done by one surgical team doing both knees (first one, then the other) in the same operation. Or there can be two surgical teams working on both knees at the same time.

Patients who qualify for bilateral simultaneous TKRs have changed over the years. Surgeons still agree that patients older than 80 years of age should not have both knees done at the same time. The risk of serious complications is just too high in this group. The biggest change in patient selection is that older, sicker adults are approved for this procedure.

In this article, surgeons review the major complications, pros, and cons of having both knees replaced at the same time. They start out by saying there isn't one most common adverse event reported in the literature.

Cardiac, pulmonary, and neurologic complications are compared. The most serious complication (death) is not any more likely after this procedure than in people of the same age dying of natural causes. Other problems that can occur include blood clots, the need for blood transfusion, and electrolyte imbalances. Gastrointestinal problems have also been reported.

The overall rate of complications is greater for bilateral TKR compared with unilateral or staged bilateral procedures. Staged bilateral refers to having both knees replaced but they are done one at a time with a certain time interval (weeks to months) between procedures. The number of patients sent to the intensive care unit (ICU) is higher with simultaneous TKRs. The number of days they stay in ICU is also greater for bilateral versus unilateral TKR.

Cardiac complications range from angina (chest pain) to heart attack, unstable heart rhythm, and heart failure. Heart attacks and heart arrhythmias top the list of most commonly reported cardiac problems.

The risk of cardiac complications in patients having bilateral TKRs is four times the risk for those having one knee done. This is one reason why patients over 80 aren't encouraged to have bilateral TKRs. The risk of heart problems increases with age. There are several reasons for this. Heart disease is more common as we age. And the heart and lungs have less reserve capacity to respond to the stress of surgery.

The most common pulmonary complications after bilateral simultaneous TKR are pulmonary embolism (blood clot) and fat embolism. When the bone is cut open, a glob of fat from inside the bone marrow can enter the blood stream. The embolism travels to the heart or brain causing serious problems such as death, heart attack, or stroke. Improved surgical techniques are helping to reduce the number of fat emboli that cause postoperative problems.

Confusion or increased confusion is the main sign of neurologic complications after TKR. This may be linked with fat embolism or the stress of the surgery. Electrolyte imbalances, dehydration, and low red blood cells all contribute to the presence of confusion. Older adults seem particularly susceptible to confusion after bilateral simultaneous TKRs.

On the plus side, there is less anesthesia used with bilateral simultaneous TKRs. Improved surgical technique means less blood loss. And rehab has to be done for both knees anyway. So the total length of time in recovery is less. There are fewer days of pain and a shorter hospital stay with fewer costs.

When making the decision to replace both knees at the same time, the surgeon must consider many factors. Besides the patient's risk factors, the presence of any other medical problems or conditions must be factored into the equation. Hospital staffing of nurses, operating room tech support, and experience of surgeon and staff are all important points.

It has been suggested by many researchers based on results of studies that bilateral knee replacements are best done in high-volume hospitals by an experienced surgeon. Usually such facilities also have adequate intensive care units to care for patients who need close monitoring.

Many other areas of concern for patient safety have been raised. For example, what is the recommended age for patients to have the bilateral procedure? Can the relative risk be determined in order to avoid depriving patients of this bilateral procedure?

What is the true cause of all these complications? How important is the health status of each patient before surgery to the postoperative outcomes? And finally, if the procedure is staged, what's the optimal amount of time between the two procedures? Perhaps it is possible to decrease the risk of complications with a specific time interval.

Hopefully, in time, more studies with larger numbers of patients will be published to determine best practice for simultaneous bilateral TKRs. Until then, each patient is treated individually. Decisions are made on a case by case basis using all current information available.

Reference: 

Nilesh Patil, MS (Orth), et al. Morbidity and Mortality of Simultaneous Bilateral Total Knee Arthroplasty. In Orthopedics. August 2008. Vol. 31. No. 8. Pp. 780-789.

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