Here, Dr. Finn discusses the successes and failures in the orthopedics implant market, and how innovation can still thrive in today's troubled industry environment.
Q: Orthopedic implants go through extensive scrutiny for FDA approval, so why are implants still being recalled?
Dr. Henry Finn: We are asking metals and plastics to replace the tissues that God made, which are biological, adaptable and dynamic; these tissues respond to stresses as well as heal, repair and strengthen themselves. I think people take it for granted that if their hip or knee goes bad, they can just get it replaced and it will behave like a natural joint. There are a lot of commercials that make it sound like that, but really the implant is so far away from the natural hip or knee joint.
Hip and knee implants have only been around for 50 years in the whole history of the world; to me, it's fascinating and amazing that we can accomplish what we do with the materials we have, which are subject to fatigue and wear. I don't think recalls occur because people are careless or the Food and Drug Administration doesn't have enough scrutiny on them. We are attempting to make implants better, but there aren't any animal models to test them in vivo and no way to test them in a live situation; we only have wear simulators and laboratory work. Our tests only look at the mechanical bearings as they would react to wear; we can't test them for how they would function in the biological human body.
Q: Are surgeons and industry taking any additional steps to avoid potential implant recalls?
HF: I think the public is very well protected from faulty devices and the FDA and device companies have done a great job. Physicians are supposed to track implants and let the FDA know about issues they see. There is the unknown biological response because we can't always predict what is going to happen in the body. However, I do think there are expectations by the public that everything can be fixed when it goes bad and bone doesn't regenerate when it's lost; you can regenerate it with bone grafts and hardware, but there are still risks.
I have to sit down with patients and sometimes say we can't re-approximate a normal joint, even if we do a technically perfect job; the implant might fail because we are asking the body to do something that isn't biologically possible. The safety factor is very high; it's about how the data is presented and how people respond.
When something goes wrong, people feel concerned about the safety of the orthopedic industry; but when you put in perspective how many millions of implants are functioning well, it changes the color of the whole story.
Q: What problems arise for surgeons and device companies when orthopedic implants are recalled?
HF: There is a myth, which may be perpetuated in the legal world, that someone who has a recalled product has won the lotto; that they will get a huge financial award from the company. Generally, that isn't true because the company had FDA approval. Just because the company has voluntarily decided that there is enough evidence to recall an implant doesn't mean that patients or surgeons should think an already-implanted device must be changed.
Oftentimes, when a recall is announced people call the surgeon's office and want to know whether they were implanted with the device. They are either afraid of what might happen or think they have a strong legal case that could result in significant financial gain. I explain that there may be only a small percentage of the implants that are defective or a clinical problem; I tell patients we will follow the issue closely but we aren't going to take the implant out just because the company recalls it. If they are asymptomatic, the components are stable, and there is no bone loss, the patient may be observed closely. We will be more proactive about testing their blood for metal ions, checking their lymph nodes and giving them X-rays more frequently, but we are going to do our best to preserve the implant and leave it there unless it absolutely must be taken out.
Q: In your experience as a surgeon and orthopedic device innovator, how can surgeons negotiate providing the best, cutting edge technology for patients while avoiding methods and devices that might be recalled?
HF: Everyone wants the newest, greatest and best thing for their patients. However, some new ideas we think are going to make things better actually become a significant clinical problem in practice. For example, when the polyethylene bearings of knee replacements were impregnated with carbon fibers to help them resist wear, they shed fibers in the joint which causes inflammation and damage to the bone. This was something that seemed better in a simulator or laboratory to engineer than in the biological practice of medicine. Someone has to think about how it will respond in the biological human body.
Everyone is trying to make treatment better, but sometimes we create a new problem. If I were having a knee and hip replacement, I would ask what device was being used and how long it has been around. If it has been around for a decade, it will statistically be better for me than one that is only a few years old and hasn't been in the public as long. This is counterintuitive because our society thinks everything that is newer is better.
I am now seeing patients whose knee replacements I did 25 years ago and it's still functioning. Back then we were quoting 10 to 15 years, but they have lasted longer. I would feel better about putting an older device with a good track record in my own body than the latest and greatest.
Q: Metal-on-metal hip implants have been one of the biggest recalls of recent years. They originally were very popular and were still recalled. Why was that the case?
HF: Metal-on-metal implants were one of the hottest items in the past decade and I thought they were a fabulous idea. I did them in young and healthy patients and none of them have ever had issues. Some of the high demand bearings are subject to having a problem if they aren't installed correctly. A device can be so sensitive that the positioning needs to be exactly right to not edgeload or generate debris; if it isn't put in perfectly it could cause problems. There also have been a few design flaws that have resulted in the orthopedic company initiating a recall.
We have a range as human beings with computer navigation and our own skills. We can put implants in with proper alignment, but that can vary five degrees in one direction or another. One implant may be able to tolerate those slight misalignments and another may not.
Q: How has the heightened regulatory environment impacted orthopedic surgeons over the past decade?
HF: The industry changed as a result of a governmental investigation in 2007 related to consultants who helped design implants. Because there were a small number of improprieties where it was perceived that surgeons were receiving financial remuneration to use devices, the orthopedic industry in joint replacement settled for deferred prosecution agreement with the government. In a negative way, it made companies unable to respond to new ideas and advance technology as quickly when surgeons do have great ideas.
However, it also avoids some of these recalls because the FDA is stricter and companies are even more careful. When you have a good idea, you need to do an analysis to see whether it is needed in the industry. Then the development team becomes multiple physicians to ensure safety and quality. Generally, engineers can't create the devices on their own; they need surgeon champions who are willing to advance the field and aren't willing to accept the status quo.
I was able to receive FDA 510(k) approval for the Finn Knee, which I developed. Before that, I would implant them on a prescription basis. It takes a lot of courage to trust in yourself and your design to do that, and it's something that doesn't happen today. After several years of lab testing, FDA approval is requested without implanting devices into patients. That's a significant change because something that could really make a difference for patients is going to be scrutinized much more carefully before it ends up implanted in the patient.
Q: Where do you see orthopedic technology evolving from here?
HF: Most new designs are philosophically based on prior art. Generally, no one is coming up with a new mouse trap. In an attempt to make the implants last longer, we created high demand bearings which perform well in the laboratory but may result in biological problems in the human body. We are at the point where we understand the biomechanics of the musculoskeletal system and in joint replacement; now we are working on how to reproduce that so the implant is subjected to as little wear as possible.
More of the changes over the past several years have to do with surface structure and articulation. Twenty years ago, the contemporary techniques for fixing the implant to the bone had been working out so well that they are still good today, with few exceptions. We keep trying to make the procedure better, but maybe we're at the point where we've gone as far as possible; that's not a reason to stop trying, but these joints function well if they are installed perfectly and correctly.
I think the emphasis should be more on technique than on new designs and materials. There is evidence that when joint replacements are done technically perfect, they are less apt to fail long term with fixation to bone.
The cement and non-cemented techniques have advanced through the years. The recalls are because debris is generated at an excessive rate which causes a biologic response in the body. Some of the greatest advances in revision products allow us to replace sections of bone and they last so much longer than we expected. The areas that are most promising for the future are segmental replacement of bone and highly porous metal augments for loss of structural bone in the pelvis, femur and tibia. For the most part, those areas haven't had device recalls; most of the recalls are related to our attempts to make better articulating surfaces.