People who have moderate to severe arthritis in both knees may consider getting double knee replacements—replacing both knees during one surgery.
Double knee replacements have similar results to single-knee replacements. Both groups of patients report less knee pain and an improved knee function.1,2 However, there are important differences between having a double knee replacement surgery and two single knee replacement surgeries.
The advantages of bilateral knee replacement tend to be associated with cost and convenience.
Less time off from work
People who have a double knee replacement only have to schedule one recovery period, and miss less work.
For example, experts suggest that a person may return to a desk job 4 to 6 weeks after knee replacement surgery.3 A person who has two separate knee replacements will take 4 to 6 weeks off work for each knee.
Less time spent in the hospital
Double knee replacement patients tend to spend at least a half-day longer in the hospital than single knee replacement patients4,5—but they only have to stay in the hospital one time. In other words, a double knee replacement might require one 4-day hospital stay while two separate knee replacements might require two 3-day stays (for a total of 6 days).
Less time in physical therapy
People who get knee replacements must attend physical therapy appointments 2 to 3 times a week for up to 8 weeks. For people who undergo double knee replacement, these appointments are dedicated to rehabilitating both knees. People who undergo two separate knee replacement surgeries require two courses of physical therapy.
Regain and maintain physical activity level
Double knee replacement patients follow a physical therapy regimen and then return to the work and activities they enjoy, uninterrupted.
A person who schedules two separate knee replacement surgeries might rehabilitate the first knee and feel frustrated that—just when the first knee is feeling great—they must undergo a second major surgery.
Double knee replacements cost less than two separate surgeries. Experts estimate a medical care costs savings of 18% to 26%.4 The exact out-of-pocket costs can vary widely depending on many factors, including insurance coverage and location.
While the advantages of bilateral knee replacement are attractive to many patients, they must also consider the disadvantages.
The disadvantages of bilateral knee replacement tend to be associated with increased medical risks, though researchers debate the exact nature and severity of these risks. Patients are advised to ask surgeons about their past experiences with double-knee replacements.
More blood loss
Double knee replacement patients are more likely to need a blood transfusion during surgery. Experts estimate that about 40% of people who undergo double knee replacement need a blood transfusion, compared to about 12% of people who undergo a single knee replacement.5,6
Increased risk of complications
The majority of double- and single-knee replacement surgeries are successful; however, complications do occur. The risk of complications is higher for people who undergo bilateral knee replacement.4,5
For example, one study found that 3.8% of patients who underwent double knee replacement experienced major complications compared to 2.2% of patients who underwent a single knee replacement.5 Examples of complications include pulmonary embolism, wound infections, and the need for a second operation.
Stay in a rehabilitation center
About ⅔ of patients who have double knee replacements are discharged to a rehabilitation center, in contrast with ¼ of single knee replacement patients.5 Numbers may vary depending on location.
Not all people consider a stay at a rehabilitation center a disadvantage—rehabilitation centers offer round-the-clock care, meals, physical therapy, and an opportunity to meet other people who have undergone joint replacements. However, many people prefer to be at home. In addition, rehabilitation centers are associated with an increase in infection risk.
Prolonged anesthesia time
Replacing two knees requires more surgical time than replacing one knee, and that means the patient must spend more time under general anesthesia. Increasing the length of time under anesthesia increases the risk of complications.
No good leg to stand on
A person who has had both knees replaced does not have a good leg to stand on, making recovery and rehabilitation more complicated. The person cannot rely on a stable leg to steady the body while standing, sitting, and using a walker or crutches.
Because of the increased risk of complications, many surgeons will perform bilateral knee replacement only if patients are in good physical condition.