Causes of Knee Replacement Pain
The most important step in finding a solution to persistent discomfort is to first determine the cause of the pain. Without this knowledge, it is very difficult to find an appropriate treatment. The most common causes of pain after knee replacement include:
Loosening of the Implant
This is most often the cause of pain years or decades after a knee replacement. However, it is seldom the cause of persistent pain right after surgery. In order for a total knee replacement to function properly, an implant must remain firmly attached to the bone. During the initial surgery, it was either cemented into position or bone was expected to grow into the surface of the implant. In either case, the implant was firmly fixed. Over time, however, an implant may loosen from the underlying bone, causing the knee to become painful.
The cause of implant loosening is not always clear, but high-impact activities, excessive body weight, and wear-and-tear of the plastic spacer between the two metal components of the implant are all factors that may contribute. Also, patients who are younger when they undergo the initial knee replacement may "outlive" the life expectancy of their artificial knee. For these patients, there is a higher long-term risk that revision surgery will be needed due to loosening or wear-and-tear.
In some cases, tiny particles that wear off the plastic spacer accumulate around the joint and are attacked by the body's immune system. This immune response also attacks the healthy bone around the implant, leading to a condition called osteolysis. In osteolysis, the bone around the implant deteriorates, making the implant loose or unstable.
Infection is a serious and worrisome concern. Any increase in pain after knee replacement should raise concerns for infection. Most often, the signs of infection are obvious, but subtle infections may be the cause of persistent discomfort. Infection is a potential complication in any surgical procedure, including total knee replacement. Infection may occur while you are in the hospital or after you go home. It may even occur years later.
If an artificial joint becomes infected, it may become stiff and painful. The implant may begin to lose its attachment to the bone. Even if the implant remains properly fixed to the bone, issues such as pain, swelling, and drainage from the infection may make revision surgery necessary.
Revision surgery for infection can be done in one of two ways, depending on the type of bacteria, how long the infection has been present, the degree of infection, and patient preference.
In some cases, the bacteria can be washed out, the plastic spacer can be exchanged, and the metal implants can be left in place.
In other cases, the implant must be completely removed. If the implant is removed to treat the infection, your doctor will perform the revision in two separate surgeries. During the first surgery, the doctor will remove the implant and place a temporary cement spacer in your knee. This spacer is treated with antibiotics to fight the infection and will remain in your knee for several weeks. During this time, you will also receive intravenous antibiotics. When the infection has been cleared, your doctor will perform a second surgery to remove the antibiotic spacer and insert a new prosthesis. In general, removing the implant leads to a higher chance of curing the infection, but is associated with a longer recovery.
If the ligaments around your knee become damaged or improperly balanced, your knee may become unstable. Because most implants are designed to work with the patient's existing ligaments, any changes in the ligaments may prevent an implant from working properly. You may experience recurrent swelling and the sense that your knee is "giving way." If knee instability cannot be treated through nonsurgical means, such as bracing and physical therapy, revision surgery may be needed.
Patellofemoral (Kneecap) Problems
Kneecap problems are a common cause of knee replacement pain. Significant forces are applied to the kneecap, even with normal activities, such as getting up from a chair or walking down stairs. Getting a kneecap to perform well with a replacement can be technically challenging even for a skilled surgeon.
Many patients focus on the knee replacement implant brand or type. However, most surgeons will tell you the brand matters much less than how well the implant is put in. A poorly aligned implant may not function well, no matter the brand. Surgeons are investigating if computer navigation will help improve implant alignment.
Knee Pain Treatment in Boynton Beach, FL
Other issues that can cause persistent pain include bursitis, complex regional pain syndrome, and pinched nerves.
No matter the cause of your knee pain – we can help you get rid of it, once and for all. Contact the post-op knee pain specialists at Personalized Painful Knee Replacement Institute in Boynton Beach, Florida, by calling (561) 903-7448. You may also request your appointment now.