Complications and Risks of Knee Replacement Surgery

Most patients who choose to have knee replacement surgery are very happy with their decision. Typical patients find relief of pain, and an ability to increase their activities. However, there are possible complications of the surgery, and why knee replacement patients may not be happy. Here are five problems that can frustrate patients who have knee replacement.


Knee Stiffness

Knee stiffness after replacement can often be treated with therapy. UpperCut Images / Getty Images

One of the most common problems people experience after knee replacement is a stiff knee joint. Often these symptoms can cause difficulty with normal activities including going down stairs, sitting in a chair, or getting out of a car.

Management of a stiff knee joint after replacement can be a challenge. The best treatment is aggressive therapy in the early stages of recovery in an attempt to avoid the stiffness from occurring. Special splints to stretch the joint are also sometimes helpful. In rare circumstances, a second surgery can be performed to allow more mobility of the knee joint.

One of the most important factors that contribute to mobility after knee replacement surgery is the mobility patients had before surgery. Patients that had a stiff joint going into surgery are much more likely to end up with stiffness after surgery. Other factors can also contribute to the likelihood of developing knee joint stiffness after replacement.


Clicking or Clunking

knee replacement
P. Marazzi / Getty Images

Patients are often surprised when they hear noises coming from their artificial joints. In general, noise without pain is not a problem, but your surgeon can tell you if there is something to be concerned about. Because artificial joints are made of metal and plastic, it is not uncommon to hear clicking, clunking, or popping when the knee bends back and forth.

There is some concern when pain is associated with these noises. In situations where knee pain is accompanied by these noises, it is worthwhile to have your surgeon evaluate. Some unusual causes of these noises include scar tissue formation, instability of the knee joint, or loosening of the implants.


Wearing out of Implants

knee replacement
Knee replacement implants can wear out over time--if they do, a second knee replacement may be necessary. Peter Dazeley / Getty Images

Knee implants don't last forever, but the goal should be for the knee replacement to last your lifetime. Unfortunately, not every implant lasts a patient's lifetime, and in these cases, a second knee replacement called a revision knee replacement, may be necessary.

Knee replacements are wearing out more commonly as younger, more active patients are seeking this as a treatment for their knee pain. With these patients, the stress and demands placed on a knee replacement are higher, and there is more of a chance of further surgery being necessary.

There is significant controversy about what activities should be performed by patients who have a knee replacement. It is known that some strenuous activities, including impact sports, skiing, and even golf, can create stress on the implants that may lead to early failure of the implanted joint. While many patients do these activities, there is some good evidence that this may lead to faster wearing on the implanted knee joint.



doctor checking IV
Jose Luis Pelaez / Getty Images

Infection after knee replacement surgery is the most feared complication of most patients and surgeons. The primary focus must be to take all precautions possible to try to avoid infection. Even with appropriate steps, sometimes infections still occur.

Knee replacement infections are generally separated into early and late infections. An early infection occurs within six weeks of the original surgery and is typically the result of skin bacteria entering the joint at the time of surgery. Typical treatment involves surgical cleansing of the knee joint with appropriate antibiotics administered for several weeks or months.

Infections that occur after six weeks from the time of surgery are called late infections. These infections typically are caused by bacteria in the bloodstream finding their way to the knee joint. These infections can be very difficult to cure, and typically require the entire knee replacement to be removed in order to fully eradicate the infection.


Blood Clot

Blood Clot
Rolf Ritter / Getty Images

Blood clots occur in the large veins of the leg and can cause pain and swelling. In unusual circumstances, the blood clot can travel from the legs through the circulatory system and to the lungs. These blood clots that move to the lungs are called a pulmonary embolism and can cause serious, even life-threatening, problems.

Most patients are placed on blood-thinning medications for at least several weeks after having knee replacement surgery. Blood thinners can help decrease the chance of developing a blood clot, but there is still a possibility of this occurring.

5 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Hatten, B. My Knee Guide. Knee motion.

  2. Hwang BH, Nam CH, Jung KA, Ong A, Lee SC. Is further treatment necessary for patellar crepitus after total knee arthroplasty?. Clin Orthop Relat Res. 2013;471(2):606-12. doi:10.1007/s11999-012-2634-7

  3. Cross, MB. American Academy of Orthopaedic Surgeons. Revision total knee replacement.

  4. Hatten, B. My Knee Guide. Infection: an uncommon but serious complication after knee replacement.

  5. John M. Eisenberg Center for Clinical Decisions and Communications Science. Preventing blood clots after hip or knee replacement surgery or surgery for a broken hip: a review of the research for adults. In: Comparative Effectiveness Review Summary Guides for Consumers [Internet]. Rockville (MD): Agency for Healthcare Research and Quality (US).

Additional Reading

By Jonathan Cluett, MD
Jonathan Cluett, MD, is board-certified in orthopedic surgery. He served as assistant team physician to Chivas USA (Major League Soccer) and the United States men's and women's national soccer teams.