Treating Infections in Artificial Joints

Dr. Miller: Artificial joints and infection, we're going to talk about that next on Scope Radio.

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Dr. Miller: I'm Dr. Tom Miller and I'm here with Jeremy Gililland. He is a Professor of Orthopedic Surgery here at the University of Utah in the Department of Orthopedics. For patients and people who have prosthetic joints or artificial joints, are they at higher risk of having an infection in that joint?

Risk of Infection in Prosthetic or Artificial Joints

Dr. Gililland: Well, the joint itself we put in is a metal and plastic joint. It inherently doesn't have its own immune system like our own joints do. So if you get an infection, even an innocuous infection in the blood stream that would have normally been cleared, there is a chance that could get to the joint and take over and so you are at more risk of that joint becoming infected.

How Do Infections Happen?

Dr. Miller: So how does one become infected? I mean, is that due to a cut or some other site in the skin that could be infected or is it some other way that you are infected? How does that happen?

Dr. Gililland: The answer is, probably most of the time we don't know how it happens. It comes about as an infection that we probably wouldn't have picked up otherwise or have been aware of otherwise. Sometimes we are aware, they had a bad urinary tract infection or they do get an infection in the skin and that then gets to the joint, but most of the time we don't know and these come on seemingly out of the blue.

How Common Are Prosthetic Joint Infections?

Dr. Miller: How often does it happen? I mean, it's not common, right?

Dr. Gililland: It's not common. We would say that in most big registries, infection in any given practice should be about 1% to 2%. There is difference in infection that happens right around the time of surgery which would be a surgical site infection which can come from either the wound itself.

Dr. Miller: The wound itself, healing, the incision.

Dr. Gililland: Exactly and that's different than infection that ensues say two or three years down the road in an otherwise well-functioning joint.

Dr. Miller: So you see infection more commonly after surgery or two or three years down the road?

Dr. Gililland: Generally what we see here is our infection rate here at the university is very low. It's less than 1% of our own infections and in cases that happen here in terms of patients getting surgical site infections, but we definitely see infections coming in from outside or infections in patients that have had well-functioning joints and that's probably a bigger problem in terms of dealing with those long-term.

Complications of Prosthetic Joint Infections

Dr. Miller: So dealing with an infection in a prosthetic joint is a different kind of beast than having an infection in a joint . . . in a normal joint.

Dr. Gililland: Correct. Dealing with an infection in a prosthetic joint is rather difficult because now you have a piece of metal in there that's infected and we are starting to learn more about infections and the way that they form and bacteria is just a single bacteria creating infection. They create a big environment of what we call a biofilm that's almost . . 

Dr. Miller: Sticky.

Dr. Gililland: Right.

Dr. Miller: They stick to the plastic and the metal and . . .

Dr. Gililland: Exactly. They almost create their own colony and their own surface that sticks to the metal and it's almost impossible to get rid of with just antibiotics.

Dr. Miller: So I think most people would believe that you might just take an antibiotic for a few weeks and then the infection would go away, but that's not really true in this situation.

Dr. Gililland: Yes, it's very, very unlikely that that's going to be successful and often we get patients that have come in and have been on antibiotics for a long period of time and that's been rather unsuccessful for them and it makes our job somewhat harder because now these bacteria can be somewhat resistant to some of these antibiotics.

Signs of Prosthetic Joint Infection

Dr. Miller: Well, let's talk about the patient who might have an infection. What signs would they look for, what symptoms would they have that would alert them to the fact that they might have an infection in that new prosthetic joint?

Pain

Dr. Gililland: Yeah, the biggest thing is pain. Most of these patients are patients that were functioning well, doing well with their arthroplasty, their joint replacement, and then they started to develop pain down the road. And whenever that happens, the patients need to go and be seen and be evaluated to make sure the parts aren't loose and there is no fracture, and most importantly, they don't have an infection.

Dr. Miller: But there could be other reasons for pain aside from the infection.

Dr. Gililland: Absolutely. Pain in and of itself does not mean infection, but it's certainly something that we ought to be looking for. Any painful joint that comes in that was otherwise well functioning always gets an infection workup in my clinic.

Dr. Miller: Would there be other things going along with the pain? So would the joint be swollen or red or will the patient have fever or chills? What kinds of things are you typically seeing in these infections that occur two to three years out?

Swelling & Drainage

Dr. Gililland: Yes. So certainly there you can have swelling about the joint, redness. You can get drainage from the wound or start to develop draining sinus tracts or sites of drainage.

Dr. Miller: That would be bad.

Sepsis

Dr. Gililland: Yeah, that's obviously, obvious signs of infection. Patients can have fevers or systemic symptoms where they start to feel sick, nauseated, lightheaded, those kinds of things. That could be a sign that they are becoming septic from this. Those are the things that are . . .

Dr. Miller: What is septic?

Dr. Gililland: Sepsis is when the body system actually becomes infected, it gets into the bloodstream and you start to have multi-organ involvement from the infection.

Dr. Miller: Fever, chills, sweats, dizziness . . .

Dr. Gililland: Blood pressure issues . . .

Dr. Miller: . . . nausea. That's actually a very severe infection and of course should be treated quickly.

Dr. Gililland: Absolutely.

How Are Prosthetic Joint Infections Treated?

Dr. Miller: So what do you do if antibiotics alone are not going to fix this problem? You as an orthopedic surgeon intervene and what are the things that you do to cure that infection?

Dr. Gililland: Generally, this chronic situation where the patient has been well functioning but now has an infection, the likelihood is it's usually an infection that's probably been there for longer than we think. We treat those infections, it's a rather invasive process. Meaning, we need to go in, we need to take out all the metal because again the metal has the slime layer that's created by the bacteria that we can't just get rid of. We think we can scrub it, but reality is our data which show that we're not very good at that. So we go in, we take all the parts out.

Dr. Miller: So this is a real big deal and somebody who has had a hip replacement, now their prosthetic is removed and they're going to need a new one at some point.

Remove & Rebuild

Dr. Gililland: Absolutely. In our minds most of the time it involves the two-stage process. Meaning, we take out all the parts, we put in a temporary joint replacement usually made out of cement with antibiotics impregnated in that cement that gives antibiotics to the bone, to the tissue. And after a period of IV antibiotics and a period of time off the antibiotics, if everything looks like it's been eradicated successfully, then we go back and try to rebuild the joint.

Dr. Miller: You talk about a period of time, how long is that actually?

Dr. Gililland: Usually three months minimum.

Dr. Miller: The other thing that comes to mind is now that the prosthetic joint is out, how does the patient get around? What do they do?

Dr. Gililland: That all depends on what we put back in. Usually we can put back in something that functions. Meaning, they have structured limb and they can still use the limb, but most of the time we don't let them put much weight on the limb, so they're using a walker or crutches to get around and trying to keep the weight off of it because again we are putting in a temporary part that's really not designed to be structurally sound for a long period of time.

Long-term Antibiotics

Dr. Miller: So they're also on long-term antibiotics during this time, is that correct? Once you take the hardware out.

Dr. Gililland: Absolutely. They're usually on a period of six weeks of antibiotics IV and then after that if everything looks like it's getting better and their labs are normalizing, then we'll stop that, we'll give them what we call an antibiotic holiday to see if their labs remain low and make sure the infection does not recur once they're off of their antibiotics.

Dr. Miller: Once you complete this treatment and get to the point where you're going to put a new joint in, how successful are you in terms of really knocking out that infection, making sure it doesn't come back?

How Successful is Infection Treatment?

Dr. Gililland: That's a tough question to answer. I think everybody thinks we're better at than we really are. If you look at the literature, it's probably somewhere in the realm of about 75% success with that type of a two-stage process. But I think it really has to do with the patient and the patient's medical comorbidities and it has to do with the bug and how receptive that bug is to the antibiotics, what kind of bug it is, how virulent it is and then how many times they have attempts at prior surgeries.

We sometimes have patients that come in that have had four or five other attempts at surgery and at that period of time, he got an infection that's been really dwelling in there for many upwards of several years and it's very, very difficult for us in those cases to get rid of it. And I would say sometimes during the realm of about 50-50.

How Can I Prevent My Prosthetic Joint From Getting Infected?

Dr. Miller: Obviously, this is a very big deal for somebody who has had a prosthetic joint put in. What tips would you give to patients or what advice would you give patients to prevent infection if that's possible?

Dr. Gililland: Absolutely. I think that's the ultimate crux to this is how do we prevent the problem from happening in the beginning. There are several things that we know put patients at risk for infection. Uncontrolled diabetes is a big risk. Being a smoker is a big risk. Morbid obesity with body mass index is probably somewhere above 40 puts you at risk. Other risk factors for infection such as rheumatoid arthritis or being on immunosuppressive drugs can put you at risk.

All these things need to be evaluated by your surgeon preoperatively before you have the initial joint replacement and that's something that we do very vigilantly here at the university. We make sure that we try to mitigate any risk factors that we can preoperatively to avoid infection in the beginning.

Dr. Miller: What about little cuts and nicks on the skin? Does that bother you?

Dr. Gililland: No, I don't think. I mean, if you have a little cut and nick on the skin, as long as it's healing well and it doesn't show any evidence of infection, I don't think you have to be extra vigilant about everything in life. I mean, I think most people have a well-functioning joint and get along very, very well and we're talking about a small percentage of people here. But I think it just takes a reasonable approach.

Dr. Miller: So bottom line is if you have a hip or a knee that's been replaced, and you have pain, you should have that checked out by your orthopedic surgeon or another competent provider that can actually look to make sure that you don't have an infection as a cause of that pain. And if you have infection, that needs to be treated aggressively.

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