The vast majority of total knee replacement surgeries are successful; however, complications can occur.
Below is a list of some potential complications. In rare instances, these complications are life-threatening. A small percentage of patients will require a second, revision surgery.
Complications tend to be higher in patients who use tobacco and who are older or obese.
Complications Involving Anesthesia
Like any major surgery involving general anesthesia, there is a low risk of strokes, heart attacks, pneumonia, and blood clots.
See Anesthesia for Orthopedic Surgery
Blood clots occurring in deep veins, or deep vein thrombosis (DVT), are a potential complication of knee replacement surgery. Left untreated, a blood clot can break free from the vein wall, a life-threatening condition known as pulmonary embolism. When caught in time, pulmonary embolism is treatable with anti-clotting medication. Devices that can be wrapped around the affected leg to provide intermittent pneumatic compression can minimize the risk of DVT.
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Antibiotics are routinely given at the time of surgery to reduce the risk of infection. Despite this precaution, infection affects 2% to 3% of knee replacement patients. 1 Mihalko, WM. Arthroplasty of the Knee. In: Azar FM, Beaty JH, Canale ST, eds. Campbell’s Operative Orthopaedics, 13th ed. Philidelphia, PA. Elsevier. 2017:396-468. In many cases, the infection can be treated with additional antibiotics. However, in other cases, infection can result in the removal of the replacement joint and can even be life-threatening if it spreads throughout the body.
While the risk of infection decreases as the surgical wounds heal, it never completely goes away. People who receive joint replacements are advised to tell their dentists before any dental procedure. Bacterial infections contracted during dental procedures can affect implants. Antibiotics can be given to prevent this from happening.
Other Risks and Complications
Aside from risks associated with anesthesia and infection, there are other potential complications:
- A prosthesis component can become loose or dislocate if it does not seal to the bone well or is misaligned.
- Legs may be slightly different lengths after surgery. In some cases, a shoe insert can remedy this problem.
- The new knee may be stiff. Most people who have undergone knee replacement surgery can bend their knees at least 115 degrees. However, some people develop scar tissue that hinders flexibility. This limited flexibility is more common in people who had limited flexibility before surgery.
- An allergic reaction to the prosthesis or bone cement can occur. In these cases, the bone cement and prosthesis must be removed.
- Damage can occur to the knee’s patella (knee cap) and/or the soft tissue (muscles, ligaments and tendons) that support the joint between the patella and the femur.
- In rare cases there is damage to surrounding arteries, veins, and/or nerves.
For the most part, complications can be treated. A surgery followed by complications may still be considered successful if pain is alleviated and function improves over the long term.
- 1 Mihalko, WM. Arthroplasty of the Knee. In: Azar FM, Beaty JH, Canale ST, eds. Campbell’s Operative Orthopaedics, 13th ed. Philidelphia, PA. Elsevier. 2017:396-468.