Partnering with your healthcare team

Knee help: deciding whether to get two knee replacements at the same time

For some individuals with knee osteoarthritis (OA), their rheumatologist or family doctor may recommend a knee replacement if other forms of treatment have not improved the joint’s ability to function or failed to prevent further joint damage. A knee replacement is a surgical procedure in which parts of the joint are replaced with artificial material to restore function and ultimately reduce pain. In some cases, where both knees are severely affected, patients might consider getting both knees replaced during the same surgery, a procedure known as a bilateral knee replacement.

A recent story published in MedPage Today, and featured in RheumNow, explored the mixed evidence and experience related to bilateral knee replacement. 

A person putting sunscreen on their knees and hands


The primary advantage to getting a combined surgery is that there is only one hospital stay and one recovery/rehabilitation period for both knees. This means less time off work, in pain and needing supportive care. In addition, the combined procedure often costs less for the patient and the provider than having them done at different times. In 2016, the Canadian Institute for Health Information (CIHI) found that the overall cost of the simultaneous procedure was $20,800 compared to $23,700 for two separate procedures. In Canada, knee replacement surgery, hospital stay and post-surgery care (such as physiotherapy) are covered by provincial healthcare plans. Due to the nature of the healthcare system in the United States, the reduced cost of surgery can make a significant difference for patients.


There is some evidence that simultaneous bilateral knee replacement can come with increased risk. For one, there is a higher possibility of serious falls and more severe debilitation during the recovery period as patients don’t have one good leg to stand on for several weeks. This means that every day activities like using the bathroom or making dinner can become very challenging. In addition, one longer surgery rather than two shorter ones means more time under anaesthesia which can increase risks of complications.

Several studies have tried to quantify the risk associated with bilateral knee replacement but there is little consistency between the studies, making data fairly unclear.

  • One study conducted in France in 2012 concluded that risks of getting both knees replaced in the same surgery were not greater than a single knee replacement. The researchers concluded that there’s no solid evidence against bilateral knee replacement
  • A 2015 study found that patients who got bilateral knee replacements were three times more likely to develop minor complications and two times more likely to develop major complications (such as anemia and blood transfusions) than patients who got two separate surgeries
  • A third study found that patients who got combined surgeries experienced no difference in length of hospital stay and complications (specifically respiratory arrest, pulmonary embolism and surgical site infection) compared to patients who got two separate surgeries. However, blood transfusion rates were higher for the bilateral knee replacement group
  • In 2016, a study by the Canadian Institute for Health Information (CIHI) found that readmission rates for patients who experienced an infection within 90 days after the surgery were higher for those who got 2 separate surgeries than for those who underwent a bilateral one. After bilateral surgery, 45% of patients were transferred to inpatient rehabilitation, where as with two separate surgeries, 90% of patients were discharged directly home

Who is a good candidate for bilateral knee replacement, and who is not?

MedPage Today interviewed surgeons from across the United States to get their perspectives on bilateral knee replacement, and while opinions can vary due to inconsistent data, there was a strong understanding that in order to reduce risk, patients should be carefully selected and generally healthy.  

The exact criteria that is used to determine whether or not a patient would be a good candidate for bilateral knee replacement differs between surgeons and institutions, but some of the most common factors are weight and age. Patients that are overweight are at an increased risk for cardiac complications during surgery, due to the prolonged surgery time. Some surgeons interviewed by MedPage Today said they would not operate on someone over the age of 75, while others spoke of bilateral knee replacement patients in their late 80’s. Conditions such as renal insufficiency, heart disease, and steroid dependent asthma may also exclude patients from being candidates of the procedure.  

When considering surgery, patients must consider what is best for themselves in terms of employment, care, and recovery. It might be helpful to consider the following questions:

  • Is my home accessible? For example, will I be able to get from room to room while both of my knees are recovering?  If not, is there another facility where I could stay during recovery?
  • Will I have support I need during recovery (such as from family and friends)?

Surgeons that were interviewed by MedPage Today said that ultimately, it is a shared decision process, where both the patient and the surgeon work together to determine what is the best option. To learn strategies for communicating with your healthcare provider, visit JointHealth™ Education.