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Hip Replacement Materials – A Complete Guide to the Best and Worst

POSTED ON IN Hip BY Chris Centeno

Hip Replacement Materials and Their Side Effects

We like treating hip arthritis with stem cells, but unlike some other areas that we treat, hips with severe arthritis can be a little harder to treat. In those cases, we either recommend the patient move from a same day stem cell procedure to a cultured stem cell procedure, or if the arthritis is very severe, we’ll push the patient toward a hip replacement.

As you can likely tell, we’re not generally in favor of amputating a joint and inserting a prosthesis, which is really what a joint replacement amounts to at the end of the day. However, if you have to have one, what’s the best option? I promised a patient last week that I would perform a medical literature review and post it, in an attempt to try and answer the question about which type of device is best.

I have to say that as I updated my literature search for the phenomenon of wear particles (debris from the device created by normal wear and tear) and the havoc they cause, I wasn’t sure exactly what I would find. Regrettably, things in that department have become worse and not better.

The Many Different Materials Used in Hip Replacement Devices

Hip replacement devices break into a few big categories:

Metal on Metal (MOM) – These are what they sound like. Both the socket and the ball are made of stainless steel, titanium, chromium, cobalt or some combination of these. One sub-type of a MOM hip is a minimally invasive model which usually is smaller in size, so it can be installed with a smaller incision.

Polyethylene and Metal on Polyethylene (MOP) – Polyethylene is basically plastic, so these hips usually have metal structural pieces and a plastic liner where the ball and socket meet. They can also have a metal ball meeting a plastic socket liner. A sub-type of a polyethylene hip is made with a newer plastic called cross linked polyethylene, which is more durable.

Ceramic on Metal (COM), Ceramic on Ceramic (COC), Ceramic on Polyethylene (COP) – Ceramic hips are made of specialized and more durable versions of the same type of material that plates and bowls are made from. There are ceramic on metal, ceramic on ceramic, and ceramic on polyethylene versions. While these are durable, they can be vulnerable to fracture and breaking under big stresses.

Wear Particles

If for some reason I would need a hip replacement, my single biggest concern would be wear particles. This phenomenon first came to light about 5 – 7 years ago when surgeons began to replace the first worn out or failed metal on metal (MOM) hips. What they found in some patients was scary. Basically, the entire area directly around the hip replacement device had turned into a mass of black goo.

Then studies were published showing that those microscopic metal shavings were leaching into the blood stream and causing elevated metal ion levels. Additional studies began to point out that some people’s tissue was so sensitive to this junk that they formed pseudotumors, which are basically big solid masses of irritated tissues, some of which could press on important nerves. Finally, genetic studies showed that not only was this tissue visibly unhappy, the cells were getting damaged at a genetic level from the wear particles.

When all of this first came to light, it looked like only MOM hips were involved. However, as the research below shows, the issue of wear particles extends to every type of hip made.

ARMD – Adverse Reactions to Metal Debris

Before we begin, it’s worth noting that there is now a name for pissed off tissue caused by wear particles. In a 90s movie, a nuclear war head falls into the wrong hands and the main character is informed that this is called a “Broken Arrow”. He responds to the effect of, “I’m not sure what’s more disturbing, the fact that we just lost a nuclear warhead or that you actually have a name for this”. I feel the same about the fact that the orthopedic joint replacement community now has a name for wear particles that cause problems in patients.

In addition to highlighting research on wear particles, I’ll also look at the durability of each type. So let’s take a look at how to navigate this minefield.

The Research on the Various Types of Hip Replacement Materials – Focused on Wear Particles and Device Failure

MOM or “Metal on Metal”

The “bad boy” of hip replacement types is clearly MOM hips. The funniest thing is that despite all of the absolutely horrific things published about these devices, you can still find Internet ads for many surgeons who will be happy to implant them. They do this by claiming that these are “minimally invasive” hips. While there’s a tiny kernel of truth in that hogwash (the incisions needed to implant them are smaller), there is nothing minimally invasive about amputating a joint and inserting a prosthesis, no matter how you skin that cat. In addition, the smaller the device, the bigger the wear particle issue.

MOM hips produce metal wear particles locally that are then taken up in the bloodstream. In general, smaller MOM hip devices (usually those used for small framed women) have a higher likelihood of producing metal wear particles. This study showed more metal ions in the blood with MOM devices compared to conventional hip replacement prostheses. This randomized trial again demonstrated more metal ions in the blood of women with MOM hips when compared to conventional hip replacement, but also noted that pseudotumors occurred both around these MOM devices and the more conventional MOP devices as well. This recent study showed that metal debris was present in both large and small MOM hip replacement devices.

The latest 2015 consensus guidelines are now not to perform a MOM hip replacement in small women or anybody with a known metal allergy. The latest study on MOM hips and pseudotumors concludes, “Adverse reactions to metal debris in MOM hips may not be as benign as previous reports have suggested.” Not good.

Polyethylene and Metal on Polyethylene (MOP)

When I initially began this literature search, I thought that MOP hips may be better in the wear particle department. After all, you don’t have metal rubbing on metal, but usually metal on plastic. However, I was wrong.

To see how bad things can get with MOP wear particles, I didn’t have to look far. This recent study from 2014 showed an awful side effect of both polyethylene and metal wear particles, a pseudotumor that invaded a woman’s vaginal tissues. This 2015 study was very concerning in that it compared MOP hips to MOM hips with regard to metal levels and chromosome damage in cells. It couldn’t conclude that one was better than the other. Based on this 2014 study, MOP hips wear less, but their wear particles produce slightly more tissue reaction than MOM hips. This is all consistent with a recent study I blogged on, showing that conventional polyethylene wear particles reduced stem cell activity in bone marrow and muscle.

If there is one bright spot in this category, it’s likely the newer highly cross linked polyethylene (HCLP). Based on this recent study, HCLP hips produced fewer wear particles than regular polyethylene. In another study of shoulder replacement devices, the lower debris for these devices was confirmed. In addition, based on this 2014 study HCLP devices seem to withstand unexpected wear and part failure better.

Ceramic on Metal (COM), Ceramic on Ceramic (COC), Ceramic on Polyethylene (COP)

Maybe ceramic is the way to go? After all, what could go wrong with installing a hip replacement device made of the same substance as dinner plates?

This 2015 randomized trial showed that COM hips still regrettably produced metal wear particles that ended up in the blood stream. Some good news for COM hips could be found in this 2015 study. It concluded that while there was swelling around these devices, when compared to minimally invasive MOM hips, there were no pseudotumors seen in COM hips. However, based on this analysis of many studies, there doesn’t seem to be any advantage of COC compared to COP. How does COM and COC compare? Ceramic on metal doesn’t seem to have the same durability as ceramic on ceramic based on this study.

Is Your Surgeon Being Paid to Promote a Certain Type of Hip?

One of the real challenges in navigating this landscape is that regrettably, joint replacement devices have been one of the worst areas of payola in medicine. As reimbursements have declined for the surgical procedures of installing and replacing devices, many surgeons have figured out that they can keep their cash flow stable by taking money from the device manufacturers. This has been the subject of many Department of Justice lawsuits through the years.

The big issue for patients is how to know if their surgeon is recommending a hip device because they really feel that it’s the best, or because they’re getting paid by the company making the device. This Propublica web-site will allow you to research your surgeon’s payment history.

Correct Sizing is Key!

It’s very clear from reviewing the medical research on this topic that a poorly sized hip device is a huge problem for many reasons. First, it will reduce the longevity of the device. Perhaps more importantly, it virtually guarantees more harmful wear particles. And since we’re talking about replacing your hip, a good fit is common sense.

Given the modular nature of these hip devices and the wide array of options, a poor fit should never happen. However, in my experience, hardware fitting issues usually happen when the operating room and/or hospital don’t have the correct size in stock on the day of the surgery. So agree before hand on the size of the components and make sure the staff has double-checked to make sure the hospital has that size in stock.

The upshot? All hip replacement devices produce wear particles. But which is best? It’s clear that when metal on metal implants go bad, things can go very bad with a local tissue reaction that can cause pseudotumors and high metal ions levels in the blood. If I had to get my hip replaced, I would cross this type of implant off my list. Ceramics still produce wear particles and have the added problem of fracturing in an active individual. Polyethylene wear particles in a MOP hip can be just as bad as those from a MOM hip. Given that highly cross linked polythylene has the least wear particles, this is likely the winner. However, realize that not as much is known about tissue reaction to cross linked polyethylene, so that recommendation may change with time. In addition, there are newer types of ceramics that once mated with HCLP could produce less debris.

The Regenexx-C procedure is not approved by the US FDA and is only offered in countries via license where culture expanded autologous cells are permitted via local regulations. 

    *DISCLAIMER: Like all medical procedures, Regenexx® Procedures have a success and failure rate. Patient reviews and testimonials on this site should not be interpreted as a statement on the effectiveness of our treatments for anyone else.
    Providers listed on the Regenexx website are for informational purposes only and are not a recommendation from Regenexx for a specific provider or a guarantee of the outcome of any treatment you receive.

    comments

    Deborah Mance says

    Thank you so much for putting this together and posting it. It confirms my gut feeling that I should put off total hip replacement as long as possible while the materials used in the prostheses continue to improve and more studies are done on their effects. It also confirms my longstanding suspicion that some surgeons may be financially benefitting from using certain hip prostheses that are not necessarily the best choive for the patient.

    One day stem cell treatment will be the standard, and we will look back at THR as barbaric at best.

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    Regenexx Team says

    Deborah,

    Couldn't agree more with that last statement! Please do make sure you've considered supplements and all less invasive options to save the joint first though. While the title of this Blog says "knee", the same applies for hips: http://www.regenexx.com/knee-replacement-questions/

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    Ianpb says

    That could explain why my surgeon was unwilling to discuss the details of a replacement hip joint for me when I asked for information. He resorted to switching the conversation to a student who was present. I have since decided put the procedure off anyway, also leaving it as late as possible in order to benefit from latest material development.

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    Regenexx Team says

    Ianpb,
    Good plan!

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    J Jenney says

    Are knee replacement joints subject to similar debris accumulations

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    Regenexx Team says

    J Jenney,
    Yes. The issue of wear particles and the body's reaction is not joint specific, but rather specific to the materials used. http://www.regenexx.com/knee-replacement-questions/ , http://www.regenexx.com/avoid-knee-replacement-if-you-have-allergies/.

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    Diana Carnes says

    I have just had my third shot (in three weeks) of Euflexxa, which my doctor and I decided to try after PRP injections did not seem to provide any improvement for my hip. The day or two after each injection has been very uncomfortable, but I am advised that I should begin feeling relief after this third shot at last. I did not understand at first that the Euflexxa was more of a lubricant than an aid to cartilage regeneration. Will this have any effect on future tries at stem cell treatments or ...anything other than amputation? I am allergic to metal and have decided to live with the hip rather than risk rejection...or now that i understand from this latest article - worse!

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    Regenexx Team says

    Diana,
    The Euflexxa will not interfere with anything going forward. It is true that Euflexxa is a lubricant and has no regenerative properties, but it can provide some relief. Best as your doing to avoid joint replacement when there is a known metal allergy. Was the PRP you received from a Regenexx Provider? I ask because regular PRP created in a centrifuge does not have nearly the regenerative and repair potential of Regenexx SCP ( our version of PRP), and regular PRP can sometimes make the situation worse: http://www.regenexx.com/what-is-prp/ http://www.regenexx.com/the-regenexx-procedures/hip-surgery/

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    mary bradish says

    Where can I get Euflexxa injections as I am faced with hip replacement also and want to wait. I am in Bradenton, Fl until April and then return to Illinois the end of April. I have been receiving prp injections in Florida but the last one did not do to much in the area of pain relief and hip replacement has been recommended by one MD and let us wait until I have some PT and then elvauate.
    Please advise.

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    Regenexx Team says

    Mary,
    In Bradenton, FL, I would definitely see Dr. Lieber: http://newregenortho.com/. They do Hyularonic Acid injections (same type of thing), but you have the advantage of he and his partner Dr. Amaroso being Regenexx Providers

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    William Bailey says

    I am scheduled to visit your clinic in January ( Dr. Bashir), for evaluation and treatment of Back and worsening hip problem, possibly associated with a THR 4 years ago. My Ortho sent me this info about the device. Can you please indicate if this device has a history of problems? It is made in Switzerland.

    U have a Medacta (company) AMIS (model) hip stem on the femur side and a Medacta Versafit socket with a dual mobility head and liner. The dual mobiity means the plastic insert for the cup moves and articulates with the cup instead of being locked into the cup. The other side of the plastic insert articulates with the metal ball that is fit onto the stem of the femoral component (hence the dual mobility).
    The theory is that the dual mobility decreases wear and the risk of dislocation.

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    Regenexx Team says

    William,
    That's great news...Dr. Bashir is brilliant at figuring out issues like this! Staff is on vacation at the moment, but we will get back to you if we can find anything out on this particular device.

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    Regenexx Team says

    William,
    In looking into this I came accross: https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfres/res.cfm?id=100899. Not entirely sure if this is what you have, but it would be worth looking into.

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    Terri Cabral says

    Thank you for this informative blog. I have been told, "Oh you need a hip replacement." like I was replacing a freaking light bulb! I am putting off ALL surgery until hip replacements improve. I have a healthy body, I am average weight and work every day. I will deal with the pain for as long as possible.

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    Regenexx Team says

    Terri,
    Thanks! While we know that goes on, it still makes us shudder. Given the nature of the surgery, that's a very good idea. As well as devices, there are also 3 different surgical approaches which would be important to look into. Obviously, trying to save your hips would be our fist choice, but we realize that is not always possible. This is a very important blog regarding joint replacement as it contains 5 questions that need to be answered before a joint replacement: http://www.regenexx.com/knee-replacement-questions/ , especially making sure the joint is what is actually causing the pain, as it could be a different issue entirely. Section 4 has good info on supplements that can help. We are working hard at adding more locations, but we are incredibly selective about who we accept to train! http://www.regenexx.com/find-a-physician/

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    Terri Cabral says

    I also wish a Rejenexx Clinic was closer!

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    Jim McAllister says

    I had scheduled hip resurfacing surgery, not total hip replacement, with Dr. Thomas Gross in South Carolina. He is one of the leading surgeons in resurfacing worldwide. He does design work with a device manufacturer and has produced a state-of-the-art cementless implant. In 4000 surgeries metal-on-metal (cobalt and chromium) ions have not been an issue for his patients. Why? According to the doctor, in spite of a recent U.K. medical review which concluded that smaller implants, predominantly women, failed more than larger implants and the procedure produced unacceptable levels of metal ions, the real problem was with surgeons. Upon inspection of the report the surgeons inexperience with this more precise surgery caused many of the acetabular implants to be placed at too high or too low an angle. Under normal joint rotation the implants' edges would not be contacted. Misplacement allowed the edges to be contacted resulting in premature wear .Unfortunately, high metal ion levels at the joint and in the blood were found,. Only 3% of hip replacement surgeries in the US are hip resurfacing. Dr. Gross' registry shows devices implanted 14-15 years still performing as expected and outperforming total hip survival. The advantage of resurfacing is the minimal removal of material saving most of the femur. I also understand the debate continues as to whether or not metal ions cause the local tissue damage or it is from other aspects But, this surgery as all are highly invasive requiring the joint capsule to be opened, the femur rotated out and machined, as well as, the acetabulum. Recovery can be varied over a period of months to year(s).
    And there in lies my decision to undergo the SD procedure. My tissue is minimally affected. the risk of infection greatly reduced and I retain my body parts. I'm in my third week. I'm still working through gluteus minimus/piriformis muscle issues in both legs caused by my arthritic left hip. The quad and groin muscles are overly protective of the left hip, but are slowly relaxing. ROM issues were a concern during my evaluation, but in the end I couldn't submit to surgery without first trying a process I have firmly believed for many years was the future and was now working for many patients.

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    Regenexx Team says

    Jim,
    There is no replacement for good research, and you've certainly done yours. Replacements are sometimes necessary, but while joints are amputated and prostheses inserted, there is no real replacement for a joint. KUDOS to you for doing EVERYTHING possible to save yours! We are pulling for you!

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    Diana Carnes says

    My PRP injections were not through a Regenexx Provider - I watched the blood (mine) separate in the centrifuge before the guided injection (ultra sound). There was no apparent improvement over the weeks. The Euflexxa a few months later did not help. I was told to quit exercising during the later treatment (3 weeks in a row) as well, and I am now behind where I was after the PRP. I had been swimming 3x week and working out with a PT 3 x week and was actually starting to wonder if I couldn't just beat the pain and live with it (with a cane and Tramadol). I am starting back into PT tomorrow. My pain management doctor suggested a "cooled radiofrequency" nerve solution: "obturator and femoral articular sensory branch neurotomy". It was explained that they use radiofrequency lesioning of those nerves to lessen hip joint pain. And that it is temporary. I have no idea what the down side of that might be, but I am still convinced that stem cells might be the answer - except that I am 69 years old. My left hip is arthritic from a horse accident, but I manage to continue to be active riding bicycles, white water kayaking...just can't walk without a cane - but with a cane I can run! PT has returned range of motion and I am working on improving that even more. I suppose that without a follow up MRI we can't know if the PRP is growing cartilage as we speak, right? How would I know? Will the hip stop hurting? Are your clinics only located in Florida? And...I feel the pain mostly in the muscles of my leg - all the way down - rather than in the hip itself...though it clicks sometimes. Diana in Anderson, SC.

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    Regenexx Team says

    Diana,
    Unfortunately, there is no way for us to predict what is expected to happen in the course of your treatment as Regenexx Platelet Procedures are very different in regenerative potential than the PRP you would get elsewhere. All medical procedures have a success and failure rate, but it was in hearing so many stories like yours that we published these two articles: PRP: http://www.regenexx.com/prp-didnt-work/ http://www.regenexx.com/what-is-prp/ Your age is not an issue. Stem Cells (and again, we can only speak about our own procedures) have MUCH greater regenerative potential than PRP, but the important thing before any further treatment would be to be examined by someone who can actually figure out what is going on. Please read http://www.regenexx.com/why-the-side-effects-of-lumbar-radiofrequency-are-worse-than-the-relief/ We currently have 31 locations, with 2 new ones coming on board soon: http://www.regenexx.com/find-a-physician/. The Regenexx Candidate Form is on this page: http://www.regenexx.com The exams are billable to insurance.

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    Derek says

    Regarding 4.HAVE YOU TRIED ALL OF THE SUPPLEMENTS THAT MAY HELP THE JOINT? from the 5 Knee Replacement Questions to Ask Before Surgery, would you recommend the same supplements for someone with Avascular Necrosis in the hips? If not, what would you recommend to try to aid in increasing blood flow to the joint and helping preserve/repair the bone?

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    Charlie says

    I waited to have my hip replaced until my range of motion and activity level was greatly reduced. Now 18 months after replacement I have good range of motion and am very active once again. The replacement was ceramic head into a cross-linked polyethylene cup. For people waiting for future improvements in materials, consider the psychological stress and the physical limitations of waiting. My stress level is greatly reduced..... so far ... and I am fully functional once again. Hopefully it will last.

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    Regenexx Team says

    Charlie,
    That's wonderful news! Joint replacement should always be the last resort, but once all other options to save the joint have been tried, it can be an appropriate option.

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    Russ says

    Let's say a patient comes to you with hip arthritis and you were to judge them not to be a candidate for stem cell therapy. The patient decides to get hip replacement surgery. Would this patient benefit from identifying issues effecting the hip using the SANS criteria even though they are not using stem cells. For example couldn't they still have neuromuscular, stability, or symmetry issues that need to be addressed before the hip replacement is performed so as to prevent premature wear of the metal and plastic parts and the resulting negative impact on their body from the metal shavings?

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    Regenexx Team says

    Russ,

    SANS is a great tool for anyone. But importantly regarding pre hip replacement, the hip needs to be identified as the source of pain and dysfuncton, and any back issues need to be identified and treated before Hip replacement. Low back issues can refer pain to the hip, and low back issues often result in poorer outcomes in Hip replacement. Please see: http://www.regenexx.com/hip-replacement-back-pain/ SANS could help flag up these and other issues. But because the hip is surgicaly removed and a metal prosthesis is inserted in it's place, Hip replacement alters the biomechanics of the body permanently, so sorting that all out after recovery with the then altered body mechanics would be a whole new process.

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    Ken Henshaw says

    And it is worthy to note that it has been identified that polyethylene liners wear at the same rate as metal on metal liners, the wear rate is almost identical and the damage is the same in the human body, due to the fact that the dysfunctional orthopedic industry finds itself along with the dis-functional FDA are in a very defensive position due to the incredibly amount of injuries that is directly related to the FDA approval of the use of the now dangerous and debilitating use of the 510-K clause which allowed untested products to be sold in the market place, for government employees to be masquerading as enlightened and helpful to administer safe and useful medical orthopedic devices to allow them to be used in corrective orthopedic surgery is mind boggling, there is no use of common sense and logic at it's most minuscule level, this is a epic total failure of professional standards by the FDA some ones head should role for this gigantic failure by this government service!

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    Regenexx Team says

    Ken,
    Metal and Polyethylene Hip Replacement Devices have actually fared worse. Please see: https://www.regenexx.com/hip-replacement-pseudotumors/

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    Diane Sorbie says

    9 years after mom hip broke. After I started itching uncontrollably and had revision but over a year later still itching. Can it be caused by mom. I had very high metal count. How does this metal get out of the body and has others had this reaction? I truly believe this has to do with some kind of allergic reactions to the metal because it started right after the break. Than you and am looking forward to seeing an answer as everything else has failed to make sense after seeing multiple doctors. I am literally itching to death.

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    Regenexx Team says

    Hi Diane,
    The same questions apply for hip replacements: https://www.regenexx.com/blog/knee-replacement-questions/

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    About the Author

    Chris Centeno

    Christopher J. Centeno, M.D. is an international expert and specialist in regenerative medicine and the clinical use of mesenchymal stem cells in orthopedics. He is board certified in physical medicine as well as rehabilitation and in pain management through The American Board of Physical Medicine and Rehabilitation.…

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