Risks of Knee Replacement Surgery

Dr. Bassam Masri, MD, FRCSC, Orthopedic Surgeon, discusses Risks of Knee Replacement Surgery.

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Dr. Bassam Masri, MD, FRCSC, Orthopedic Surgeon, discusses Risks of Knee Replacement Surgery.
Video transcript

Featuring Dr. Bassam Masri, MD, FRCSC, Orthopedic Surgeon

Duration: 4 minutes, 3 seconds

So with any surgery there are risks with a knee replacement that one has to know about and decide if the risks are worth the benefits that they’re going to get from the knee replacement.  

The major thing that somebody needs to know is that with a knee replacement, much more so than other operations such as a hip replacement, it’s really about managing expectations.  

So the surgeon’s expectations should be in line with the patient’s expectations because not every patient is pain free after surgery and that has to be clearly discussed between the surgeon and the patient, so that the patient can make an informed decision as to whether their pain is severe enough to warrant the potential risk of having ongoing pain after surgery.  

Once a patient has decided that yes, their pain is significant enough and they’re willing to accept the risk of ongoing pain, albeit not severe, then this will improve the potential satisfaction for the patient because now the expectations are well aligned.  

In addition with any operation, particularly with orthopedic surgery, there are risks of a blood clot in the leg that can go to the lungs. And that happens in anywhere from two to five percent of patients. To minimize that risk many surgeons recommend that their patients take anticoagulants, and there are a variety of medications that can be taken, and it’s up to the individual hospital, individual surgeon, to make those recommendations, but it’s very important for the patient to comply with those recommendations to minimize that risk.

Having said that, it does not eliminate the risk, but it minimizes it. Another risk is that of infection. A little bit of redness around the wound or what’s called the stitch abscess is not a real infection. What we’re more concerned about is a deep infection where the knee gets filled with pus, and that would require at least one or two operations to fix the problem, and that happens in anywhere from one to two percent of patients, not common but if it happens it’s a pretty devastating complication.  

Other risks include stiffness. So a patient may come to the office at six weeks and they only have 60 degrees of flection let’s say. That patient may require what’s called a manipulation under anesthetic, which is really physical therapy under general anesthesia, where the patient is given anesthetic and the surgeon bends the knee and then they start physical therapy afterwards. You can minimize the risk of stiffness by complying with the physical therapy instructions and by bending the knee all the time. This is why it’s important to keep moving.  

Other risks include injury to nerves and blood vessels, where you get what’s called a foot drop, where you can't lift the foot up.  The risk of that is extremely miniscule, something like one in two to five thousand, but it can happen. Injury to the artery behind the knee is extremely rare, but it can happen. If it happens it can be repaired.  

Long term risks include failure of the knee replacement. And the failure rate depends on the age of the patient and this is why it used to be thought in the past that if you’re young you shouldn’t have a knee replacement. So if we look at the risks of revision at 15 years, if you’re under 55 the risk is approximately 30 percent. And if you’re over 55 the risk is approximately 15 percent.

So in generic terms you can think of the risk as one percent per year. So at five years it’s a five percent risk of needing a second operation and so on and so forth. After 15 years the risk obviously goes up. But if that happens then it can be redone.  

So as with any operation there are also general medical risks such as a heart attack, stroke, pneumonia, bladder infection, but those are relatively rare. And if one is healthy these are extremely rare.  

If you have any further questions about the risks and benefits of a knee replacement consult with your surgeon.

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Presenter: Dr. Bassam Masri, Orthopaedic Surgeon, Vancouver, BC

Local Practitioners: Orthopaedic Surgeon

Video Quiz ( 64 participated.)

Test your knowledge by answering the following questions:


Once a patient undergoes knee replacement surgery they are guaranteed to be pain free.


Some of the risks of knee replacement surgery include blood clots, deep infection in the knee and stiffness.


Another risk of knee replacement surgery is long term failure of the knee replacement after 15 years.

This content is for informational purposes only, and is not intended to be a substitute for professional medical advice, diagnosis or treatment. Always seek the advice of your physician or other qualified healthcare professional with any questions you may have regarding a medical condition.

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