Ask Dr. Breien: How Is A Failed Knee Implant Treated?
Dr. Breien explains the most common causes of a failed knee implant, and the repairs available.
Knee replacement surgery is an excellent option when conservative therapies fail. “A knee injury or arthritis can severely limit day-to-day activities,” says knee surgeon Dr. Kristoffer Breien. “And painful knees can hamper patients in a broad age spectrum. But there is a limit to the life span of a knee implant. One of the questions my patients ask is ‘What are my treatment options for a failed knee implant?’”
Factors that can cause a knee implant to wear out
“Weight, activity, and implant type are the best predictors of a failed knee implant,” says Dr. Breien. “Weight and activity matter most. Maintaining a healthy weight is important for lots of reasons. If you have a knee implant, excess weight is going to put more stress on that implant with every step. Over time, that wear and tear adds up. We also try to dissuade knee replacement patients from doing a lot of running or jumping.”
Two common reasons for a knee replacement to wear out
The degree of difficulty in replacing a failed knee implant depends on why the implant failed. “Let’s talk about the two most common reasons for implant failure,” says Dr. Breien. “Either the plastic components of the implant wear out, or the entire implant loosens. It’s not surgically difficult to redo a failed knee implant. But the patient outcome is what matters. A second implant is never as good as the first one, unless all you did was wear out your plastic.”
When wear and tear of plastic components causes a failed knee implant
“If the plastic bushing in the implant wears out, you can change it without replacing all the metal parts,” Dr. Breien explains. “When younger people get these knees, I tell them to be nice to their knee, because we don’t have plastic that’s going to last for their lifetime. However, plastic exchange is the easiest redo.
“Plastic wear doesn’t usually hurt the patient as it happens. We follow our knee replacement patients every three to four years. X-rays will tell us if the plastic parts are getting narrower and the metal parts are getting closer and closer together. When a failed knee implant can be corrected with plastic replacements, we simply put in new plastic. I do have to open the joint, but I don’t have to cut bone. I tell my patients that a plastic exchange is about one-third as painful as the original replacement. Recovery time is minimal. Afterward, the knee should feel the same. This procedure can theoretically give a patient another 20 years on that knee.”
When an implant comes loose from the anchoring bone
“Every knee implant has metal components that are solidly attached to the bone in the knee joint,” explains Dr. Breien. “If the entire implant comes loose, then you have to take the entire implant out and replace it. Replacement for this type of failed knee implant entails large revision parts and stabilizing rods in the leg. The outcome is probably not going to feel as good as the first knee replacement.”
Summit uses implants with the best track record for successful outcomes
Because the most reliable outcome data is based on patient trials, Summit uses implants with a proven track record for safety based on extensive patient data. “We are always monitoring emerging new implants, and we follow the trials,” says Dr. Breien. “We can’t guarantee how long your implant will last. But we can tell you that we use the implants with the most substantial data supporting safety and good outcomes. That’s what I would want for myself, and that’s what I recommend to my patients.”
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