Today I finish my conversation with Physical Therapist Amy Dougherty on specific problems that may arise with metal-on-metal artificial hip failures:
Clay: Over the past ten years you have seen a lot of metal-on-metal hip implants. Several years ago an attempt was made to put a metal-on-metal artificial hip together, and that was supposed to last forever, or last a whole lot longer, and it turned out that it was problematic. And I know you have had many patients who have had that [implant]. What did you see out of the metal-on-metal hip implants when they were failing?
Amy: Again, the first cardinal sign that I saw was chronic pain, an inability to weight bear normally through that joint. So even after normal hip replacement, the patient should be able to weight bear through it. It should not feel like they collapse on that hip, and so a limp that never resolves or an inability to get away from an assistive device. So, I had a patient in her 50s that could not get off a walker. She was 50. She was playing tennis five days a week before she had her hip replaced. Yes, with the metal-on-metal she suffered metallosis and she had an overt failure of that joint replacement. She was a candidate for this new [metal-on-metal implant], now widely known to be a bad device, because she was so young, active, fit, and healthy. It was supposed to last for longer. It was supposed to allow her to have more function larger range of motion, less risk of dislocation and all of those things. So as we know, that did not really work out so well.
Amy: So the folks that had the metal-on-metal problems, metallosis was the biggest problem that ended up causing really frankly catastrophic changes in these people’s lives because the metals in the two appliances, they ground on each other and it leaks metal, particularly cobalt. That was a big metal that became known to become systemic and to basically create toxicity in the tissue surrounding the joint.
The metal would basically eat or erode away musculature bone, osteolysis was one of the biggest problems where it caused bone to basically just break down and be eroded away. I was actually in the operating room and saw some revision of a hip that experienced metallosis. And in the revision the musculature that was away from the hip, so when you go in to do a hip replacement, obviously, it is an open field and so you can see all of the connective tissue all the layers of musculature of the capsule of the joint this particular patient.
The capsule of the joint was this dingy gray looking color. You knew inherently. You did not have to know anything about science or medicine to know that it is probably not supposed to look like that. And what is astounding was how far away that metal leached into the musculature and so because it is toxic, because it is corrosive, that tissue had to be ripped [out]. It had to be excised. So some people lost part of their musculature and some of it was very important musculature around the hip in regards to stability and mobility restoration in the hip.
So, because the metallosis affected the bone, revision surgeries then became a bit tricky because, so when these folks went in for their first hip replacement, they had this beautiful landscape. They had a bad hip. They had a bad articular surface, but the landscape around it, and by that I mean the bony components that are going to hold that new joint, they were healthy. Otherwise, they would not have been a candidate for a hip replacement. Okay, so they had a healthy landscape to put those two new pieces in the socket. The acetabulum and the femoral head. So, once the metal started breaking down some of the bone, now all of a sudden you have got a landscape. It is not all that great in regards to the how to receive this new joint. So these folks had significantly limited post-op. They had to protect those joints dramatically for long periods of time so that could allow this bone that had really taken a hit to grow into the new prosthesis, which is how you heal a hip replacement. So, it made the post-operative course significantly different than a primary hip replacement where you walk immediately after surgery. I mean, I have seen patients ten days post-op, that are already on a cane and have a pretty decent gait. So–
Clay: Well, that is kind of horrifying, a revision is one thing but a revision when the whole landscape of the hip and the thigh and the leg and all that area is severely compromised. It makes the revision surgery less likely to be successful. So, that gets me to this question. I know you have seen it quite a bit. Tell me what the rehab might look like and I know it is different for all people. But what might the rehab look like for a person who has to get multiple surgeries on the same hip? I know it is compromising. How would it be compromised?
Amy: So that same patient when they had the first hip put in, when as soon as they started physical therapy within 24 hours of their surgery. They would be putting weight if they are usually what is called “weight bear,” as tolerated. So basically, we want you putting weight through that new joint. So as much weight as you feel like you can safely place through that leg using a walker, because everybody starts out on a walker, their weight bear is tolerated.
So, that is in the primary hip replacement that is uncomplicated. In just a plain revision, they can be non-weight-bearing for four to six weeks. So just right out of the gait. They are not putting any weight at all through it for four to six weeks. In the cases where these folks had really substantial metallosis, sometimes that non-weight-bearing was extended 8 to 12 weeks. And now you are talking about being completely non-weight bearing which, by the way, is very difficult to do.
Amy: It is really hard if you think about how difficult that is for your upper body and for your contralateral side, for that other leg to be completely off that leg for anywhere from six to twelve weeks. And the reasoning is because that landscape they wanted, the surgeons wanted, every opportunity for that bone to accept that new part for it to heal because bone is live. So it grows into the prosthesis, into the implanted part of the prosthesis.
So they want that bone grow in because over the course of time, that is where the fixation actually lives. That prosthesis becomes incorporated into the bone itself. It great becomes part of that bone. So that is one of the biggest things that occurs postoperatively in those revisions. And so, then you have to think about everything that happens with that revision. So let us say your non-weight-bearing for six weeks, well, if you took your very healthy hip and you got off of your leg for six weeks, you would be astounded at how much strength you lose.
Clay: All right.
Amy: It is astounding through the entire extremity. And so there is profound strength loss.
Clay: So what is your medical opinion about the likelihood that a follow-up surgery or revision surgery will be successful? I mean does the chance for success just drop through the floor once there has been a failure of an artificial hip? Such that you say to yourself “My goodness. This person is going to really struggle,” or is it case by case? And in a lot of cases revision surgery can be fine for a patient.
Amy: I think that any joint replacement hips included the first one that you get because of that pristine landscape is the best chance you have to have a great outcome. Every time that that surgeon has to go back in, the opportunity for a great success go down.
Amy: And that is just the way it is. But the problem is that, like for the folks that had these metal-on-metal joints, they did not have an option. I mean, they were in such profound pain. The debility they had to get that hip taken out. And they just basically had to deal with whatever that metal did to the surrounding tissue and they had to try to protect the healing tissue the best they could and understand that their outcomes were going to be less than perfect.
Amy: Not what they had planned. Not what my fifty year old patient who had every plan of going back to the tennis court because that is why she had a hip replacement, because we know that she can go back to doubles tennis.
Clay: Right. Did not happen.
Amy: No, matter of fact, she was just happy frankly at the end of the day after a exhausting very very physically and emotionally challenging rehab process. She is happy to be able to walk and to not feel like she has a nail being driven through her hip every time she way bears.
Clay: I see.
Amy: So her measure of success changed dramatically after her revision.
Clay: I bet. Well, let me try to end on a slightly more upbeat note. Have you seen better outcomes in the last few years since we have learned what we have learned about metal-on-metal hips? And have there been fewer revision surgeries among your patient population?
Amy: There absolutely have been. As matter of fact, it probably in the last four years, I have had quite a few patients that have not even needed to do anything with me postoperatively. They were strong enough, healthy enough, and had prepared themselves for their surgery enough that they did not even need to do PT. Basically, they just had to protect their hip for a little bit, gradually get their weight back on it. And so, there is no question that the hip surgery that is going on right now, the total hip replacement surgeries, and I am seeing are phenomenally successful. If we look at the whole spectrum of success, I think the last that American Academy of Orthopedic Surgeons was a 95% success rate. I mean that is pretty high success rate for a very dramatically large spectrum of people [aged] 11 to the 90s. So, you know, it inherently has great outcomes. It is just when the outcomes are not great, it is bad.
Clay: Yes. I have seen it in my work as well. This is what I wanted to talk to you about today. This has been fantastic.
Amy: Well, I hope I answered your questions adequately, and I am happy to talk with you.
Clay: Well, thank you so much and who knows, if I have another subject to discuss, maybe we can do this again one day.
Amy: I would love to do that, Clay.
Clay: Well, thank you Amy. I really appreciate your time.
Amy: My pleasure. Have a great night.
Clay: You too.
Note: You can also listen to this conversation with Amy Dougherty in my podcast. If you want to talk about a possible defective artificial hip case, call me: 919.546.8788.