Does Your Knee Still Hurt After A Replacement? It Might Be An Allergy

If you’ve had a knee replacement and are still in pain, you might be allergic to the metals used to stabilize the joint. It’s something Dr. Peter Ameglio and the entire team at Gardner Orthopedics is putting on their radar, but it’s a theory that is not without controversy.

“Some physicians don’t believe it is a real thing,” says Dr. Ameglio about the metal allergy. He continues, “It’s a diagnosis of exclusion. If someone comes in with a painful swollen knee, you have to rule out a low-grade infection or instability of the knee replacement, among other reasons.”

In some cases, the pain is actually coming from somewhere other than the knee. Most commonly a hip disorder refers pain to the knee.

“Of the people who have had total knee replacements, up to 20% are dissatisfied. This is one of most successful orthopedic surgeries we perform, but so many people are still dissatisfied. Why is that?” asks Dr. Ameglio.

Knee replacement surgery is more of a resurfacing rather than a replacing. Dr. Ameglio compares it to capping a tooth, saying, “If you put in a new surface and the ligaments are nicely balanced, the painful joint surface is gone. It should not hurt.”

Between 10-15% of the population has a sensitivity to metal with nickel being the most prevalent, according to the surgeon. Nickel is commonly contained in knee replacements along with cobalt and chromium. Have you ever tried on costume jewelry that causes your skin to turn red, and burns or itches? It’s likely you have a sensitivity or allergy to that metal.

The theory is the same when considering metals used on the knee. Dr. Ameglio says, “Some people have trouble sleeping. They start having joint pain in other areas of the body. Some are so desperate they come in saying, ‘I just want it out of my body’.”

There are no guidelines or evidence-based treatment for metal allergies in regards to knee replacement and that is what many physicians rely on.

Dermatitis or eczema on the skin around the knee gives a clear indication of an allergy. However, if someone comes in with a painful, swollen knee, the diagnosis is not so simple. It requires an extensive workup with bone scans and blood work.

Unfortunately, pre-screening for metal allergies is not an option, according to Dr. Ameglio, who says you have to be exposed to the allergen before you can test positive for it. If a metal allergy is thought to be the reason for your pain, the solution is a replacement of the original knee replacement, using an alternative material such as titanium or zirconium, a ceramic-coated implant.

There are no guarantees on the success of a revision surgery, given the lack of evidence-based guidelines for surgeons to follow. Due to this shortage of patient studies, surgeons are left to make decisions on a case-by-case basis.

People may go from doctor to doctor being told they are fine, but it’s not fine if the knee still hurts. This is a real thing that should be investigated,” says Dr. Ameglio.

If you have had a hip or knee replacement and are still in pain, talk to your surgeon about metal allergies or call Gardner Ortho­pedics at 239-277-7070 for a consultation.