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Comparing hip resurfacing to standard total hip replacement
Hip Resurfacing is a type of Total Hip Replacement (THR) that allows full athletic function and lasts much longer than a standard stemmed THR. No prosthetic hip totally recreates a normal hip, but hip resurfacing comes much closer.
Most people with severe hip arthritis are very satisfied with total hip replacement (THR); older folks who are happy to walk pain-free and golf are usually satisfied. However, there are several reasons many people still would prefer a better option:
- Many younger people want a chance to return to regular vigorous exercise, impact sports, or heavy physical work.
- Some people just don’t want so much of their own bone removed and a large “spike” driven into their femur.
- Everyone wants the longest-lasting artificial hip.
Unfortunately, most joint replacement specialists who perform THR, never inform patients that there is another option – Hip resurfacing arthroplasty (HRA). Most patients with a severely arthritic hip are just told that they need a THR. If they know enough to inquire about hip resurfacing, they are usually provided with incorrect or outdated information to discourage this option. This website provides extensive explanations and, most importantly, data to counter this misinformation.
Why is hip resurfacing superior?
- Better Function - Full athletics and heavy physical work
- More Durable - 99% 17-year implant survivorship
- Superior Stability - 10-fold lower dislocation risk
- Improved life expectancy - at least 25% better by 10 years
- Less chance of wear/corrosion failures - None since 2009, in over 5000 cases
- Bone Preservation - Only 4mm of bone removal from either side of the joint
- Lower fracture rate- 0.2% in first year and 1% by 17 years. compared to 1-2 % in 1 year and 7.7% in 20 years (Mayo clinic)
Great advances have been made in hip resurfacing since I started in 1999. Most joint replacement surgeons have not kept up with the data. When comparing THR to hip resurfacing there are many criteria that can be used to evaluate the two operations.
Hip resurfacing comes out looking better by ALL criteria. Hip resurfacing gives a better functioning hip, a more stable hip, it preserves bone, has a lower wear/corrosion rate, and far better durability. The long-term mortality rate of patients with hip resurfacing is more than 25% lower than similar patients with THR.
What then is the advantage of a THR?
It is the traditional way that a severely arthritic hip is repaired, and most orthopedic surgeons are trained to perform it with good outcomes. Hip resurfacing is a much more complex operation that most orthopedic surgeons do not have the necessary skill to perform. Many have tried and failed to achieve similar outcomes as they can with THR and have therefore reverted back to THR. Others are intimidated to try to learn this more complicated operation or because of the climate of fear created by "thought leaders" in THR around the subject of metal ions.
These opponents to hip resurfacing claim that hip resurfacing has a high rate of failure due to adverse wear and that THR is functionally equivalent. They are mistaken on both counts. All surgeons have opinions, and the majority are against hip resurfacing; on this website, I counter these opinions with facts. You get to be the judge.
How is hip resurfacing different than THR?
Hip resurfacing replaces only a thin layer of bone on either side of the joint with metal creating new artificial cartilage layers. The central problem we are correcting when a patient has severe arthritis is surface cartilage loss. In hip resurfacing, only 4mm of bone is removed from either side of the joint to make room for the two new thin artificial surfaces. In standard THR, much more bone is removed and replaced by metal and other materials, creating an artificial hip that is less like the natural hip.
In both THR and hip resurfacing, the same amount of cartilage and bone is removed from the socket (acetabulum) side, the difference is on the femur, where resurfacing requires replacing only a thin layer of the femoral head. With THR the whole head is amputated, and a stem is driven deep into the femoral shaft, this stem then supports a smaller-than-natural artificial head.
Why is so much bone removed in a THR? Traditionally the materials used to line the socket are quite thick. After removing only 4mm of bone, a socket component of 10-12 mm thickness is placed. The diameter of the natural socket is therefore reduced considerably in the new artificial socket. This requires a smaller head size.
It is not possible to shave the femoral head (ball) enough to make room for a smaller ball without cutting into the femoral neck. Therefore, the head is amputated, and a stem is fixed into the femoral shaft. This allows a smaller artificial head to attach to this metal stem. This smaller ball then fits into the smaller socket.
In a hip resurfacing, the same 4mm of socket bone is removed as in a THR, but it is replaced with a thinner all-metal 4mm socket piece. The thickness of the socket implant matches the thickness of the bone removed; thus, the natural hip socket size is retained. On the femoral ball, a 4mm surface is also removed and replaced with 4mm of metal. The result is an artificial hip that more closely simulates the natural hip. Mimicking the biomechanics of the natural hip joint of course leads to a more normal feeling and functioning joint.
Why is function better with Hip Resurfacing?
Walking and sports
Unlike THR, hip resurfacing allows athletic people to return to full unrestricted sport. A hip resurfacing mimics the natural hip joint more closely. The load is passed from the femoral component in a more natural fashion to the top of the head, rather than through the THR stem to the femoral shaft (thigh bone). Loading the thigh through a stem feels unnatural to most people and results in limitations.
At least 11 scientific studies demonstrate the superior function of hip resurfacing. Many other studies show no difference. None show the superiority of THR. The studies that show equivalence just place the bar too low. If I place the bar only one foot off the ground, any patient can hop over, and we can erroneously conclude that there is no difference. The three best studies showing hip resurfacing superiority are as follows.
- Pritchett reported on 332 patients in which he had performed a THR on one hip and a Hip Resurfacing on the other. 86% preferred the resurfaced hip. Only 6% preferred the THR.
- Barrack evaluated several hundred matched young patients with THR and Hip Resurfacing with detailed activity questionnaires that took the bar way above standard hip questionnaires typically used in THR research. “When controlled for age, sex, and premorbid activity level, patients with hip resurfacing had a higher incidence of complete absence of any limp, lower incidence of thigh pain, lower incidence of perception of limb length discrepancy, greater ability to walk continuously for more than 60 minutes, a higher percentage of patients who ran after surgery, greater distance run, and higher percentage of patients who returned to their most favored recreational activity.” UCLA Activity scores were also much higher for the resurfacing group.
- Cobb has done numerous gait studies demonstrating that THR and Hip Resurfacing patients walk equally well at slow speeds, but the gait at fast walking speeds is more normal in Hip Resurfacing patients.
Two anecdotes that illustrate these findings are the stories of Bo Jackson, the superhuman athlete who suffered a severe injury to his hip in football. He had a THR and struggled afterward to perform as a designated hitter in baseball. He was unable to play football and baseball, he struggled for 2 years as a designated hitter and retired. In the 23 years since then, he has already undergone 2 revision surgeries as benchmark data would have predicted.
On the other hand, Andy Murray returned to win the European Open men’s singles tennis event 1 year after hip resurfacing and was recently ranked #37 in men’s singles tennis. There is a large gap in physical demands between men's singles tennis and a designated hitter in baseball.
There are two biomechanical reasons why hip resurfacing is more functional. Normal hip bearing size provides near-normal stability. Load transfer to the top of the head is more normal than loading the thigh through a THR stem. We will discuss stability later.
The THR stem is the main reason patients struggle to perform after THR. In typical less-active patients who have THR, approximately 30% report slight or mild thigh pain. 3-5% report moderate to severe thigh pain. This is caused by a load transfer from the stem. This is just with activities of daily living. When patients with THR try to return to impact sports (see Barrack above) they are unable. Many patients have pain due to the abnormal load transfer of the stem to the thigh bone (femur). With impact, the sensation is naturally more pronounced and THR patients are often unable to overcome this discomfort. On the other hand, about 40% of my hip resurfacing patients choose to participate in impact sports, the only limitation is occasionally in distance runners. In some patients running more than 2-3 miles is limited, but many who have the desire are even able to run triathlons, marathons, and even ultras.
If you want to walk normally at fast speeds or if you want to run or play impact sports, you want a hip resurfacing.
Hip resurfacing solves the instability problem we have gotten used to with THR. The bearing size in hip resurfacing is normal. In a THR, the bearing size is much smaller than the natural size making a THR unstable. Chronic instability is the leading cause of revision surgery in THR. 3% of THR dislocate within the first few years and 5% by ten years. Half of these patients develop recurrent instability and require revision surgery, which is only 70% effective in resolving the problem. Hip resurfacing, in my hands, carries a 0.3% dislocation risk and only a 0.04% risk of recurrent instability requiring revision.
The rare cases of hip resurfacing instability are related to patients bending their hip too far or falling before the cut ligaments and muscle envelope has had a chance to heal after surgery (6 months). Unlike for THR, no permanent hip position restrictions are required after 6 months for Hip resurfacing patients. When the muscles and ligaments are healed, near normal hip stability iis present.Yoga, gymnastics, kayaking, rock climbing, ballet, and other high-range-of-motion activities can be resumed as normal without any restrictions or fear of hip dislocations. I have even had a number of patients perform the splits after they are fully healed.
Is THR or Hip Resurfacing more durable?
Hip resurfacing is more durable than THR in all patient subgroups. Currently, my 17-year implant survivorship is 99%. Only ceramic-ceramic THR in Young-Hoo Kim’s series from Korea can equal this outcome in young patients (but they still acn't function as well due to the stem).
Even if hip resurfacing had a higher failure rate, I would choose this operation for myself because of the more normal function it allows. In fact, this is the reason why I started to perform hip resurfacing in 1999. At that time early data from Derek McMinn in Birmingham England came to my attention. Metal-metal hip resurfacing seemed to work well in the short run, solving the early failures of metal-on-plastic hip resurfacings encountered in the 1970s.
The problems young people faced with THR were well-known. Many of the early adopters of hip resurfacing reasoned that patients would be well-served if we could buy them 10 years with a hip resurfacing to delay the inevitable THR. Surgeons and our patients took a chance to see how many could get ten years out of a hip resurfacing. This gamble paid off. My first cohort of Corin hip resurfacing patients achieved 89% ten-year implant survivorship and 84% 20-year implant survivorship. Not only did we buy most patients 10 years with a bone-preserving implant, but they had a higher chance of making it 10 or 20 years than if they had a THR instead.
As hip resurfacing has improved, implant survivorship has now reached 99% at 17 years in my practice. The only THR that can approach these results in young patients is ceramic-on-ceramic uncemented THR, which is about as infrequently offered to patients in the US as metal-on-metal hip resurfacing. The main reason that ceramic-on-ceramic is not used is the 5-10% rate of loud squeaking reported in many studies. US patients don’t accept this problem and request a revision for an otherwise well-functioning THR that is squeaking, resulting in a high overall failure rate. Korean and French patients don’t seem to be bothered by squeaking as much because there are few revisions for squeaking reported from these countries. If you can tolerate a 5-10% chance of loud squeaking from your hip, then a ceramic-on-ceramic THR can last as long as a metal-metal hip resurfacing.
In other words, if loud squeaking is considered a failure (and revision is performed) then ceramic-ceramic THR has a higher failure rate than metal-on-metal hip resurfacing. In the Korean and French reports, no one gets revised for squeaking; I wonder if squeaking is not happening, or if the patients are more accepting of this problem.
A related question is whether hip resurfacing is as durable as THR in all patient groups. The answer is that in the last 10 years in my practice, all patient groups have had a lower 10-year failure rate with hip resurfacing than THR except when compared to expert surgeon series of ceramic-on-ceramic THR published from Korea.
In the first 10 years of my hip resurfacing experience, young men (under 60) with osteoarthritis enjoyed the lowest 10-year failure rate, far surpassing THR failure rates in young patients. Women had a higher failure rate than men, but young women still fared better with hip resurfacing than if they had a THR. Older patients had a higher failure rate with hip resurfacing, mainly because THR failure rates in older folks were lower than in young patients. Patients with dysplasia (mostly young women) and osteonecrosis (mostly young men) had a slightly lower failure rate with hip resurfacing than THR.
Now, 17-year failure rates for my hip resurfacings stand at 99% for all groups, surpassing THR in every category except for ceramic-on-ceramic as discussed previously. This even surpasses the 95% 10-year failure rate reported in registries for patients with a mean age of 70 years. This is especially remarkable because my patient cohort is much more demanding on their implants; 40% participate in impact sports. They are more active as a group than the average THR patient, yet their hip resurfacing still is more likely to last longer.
In “benchmark” registry data (England, Sweden, and Australia) the 10-year implant survivorship for THR is 95% at age 70 and 83% at age 50. My hip resurfacing 17-year survivorship is currently 99% far surpassing all registry benchmarks for any age, diagnosis, or sex.
Registry data (benchmark data)
When comparing the durability of joint replacement, the typical measure in most studies is implant survivorship. The accepted statistical method is using the Kaplan-Meier (KM) formula. The endpoint that is typically measured is any failure resulting in revision surgery. Patients with various lengths of follow-up since surgery are entered, revision dates are entered, and dates that patients pass away are entered. The formula then provides the estimated implant survivorship for an interval corresponding to the patients with the longest follow-up. If I have been performing a certain operation for 15 years, I can estimate 15-year implant survivorship even though some patients in the study were operated on only 2 years ago. That is why KM data is labeled as estimated.
The major joint registries (Australia, Britain, and Sweden) all report data this way (most individual surgeon series also use KM statistics, I report my data this way). These three are the best joint registries in the world. In these countries, all joint replacements in the country are recorded with the registry by law. All revision surgeries are also registered. Therefore, when any operation is revised later it is considered a failure, and the time to failure is known. We think that most replacements and revisions are entered, but I have been unable to find any reports verifying how high the capture rates are. I believe that patients who die are also captured from death records. There is also an American registry, but it has a very low capture rate and is, therefore, unable to provide any meaningful data on implant survivorship.
Registry data can be analyzed for different implants, but not for individual surgeons. Therefore, it is helpful in providing average surgeon data. The mean age of THR patients in all registries is 70 and the mean 10-year implant survivorship is 95%. This is what the average surgeon can achieve with the average implant in an elderly patient. But, of course, some surgeons are above average, and some are worse. Individual published surgeon series (scientific papers, not registry reports) can give you a clue on how the individual surgeon performs if compared to registry benchmarks. Most surgeons do not provide this data to patients, but you can search for it on PubMed. Most surgeons never collect this data and can therefore not give you accurate data on their outcomes. My data is reported on this website in “Latest Results” and also in the form of peer-reviewed scientific papers in “Scientific Publications”.
While the three major registries are a great source of benchmark data, they do have their flaws as any scientific report does. Other than the major problem of the high degree of individual surgeon variability, the following are problems that you need to be aware of:
- Some surgeons may be better at performing THR, others better at hip resurfacing.
- If a hip resurfacing suffers a femoral neck fracture it is “revised” to a THR (failure), but if a THR suffers a fracture it may be repaired around the stem with cables, which is a similar magnitude of surgery but is not counted as a revision (negative bias for hip resurfacing).
- Hip resurfacing is a relatively new operation with many surgeons performing very few of them without prior specific training, while THR has been around for over 70 years with many surgeons performing high volumes of them (Negative bias for hip resurfacing).
- Age of the patient has a strong effect on THR durability. Young people have a much higher failure rate. There are several possible reasons for this. First, young people on average are more active and place more wear/stress on any implant. Second, older people are less likely to be revised if their implants fail. They just live with a failed implant because they are unable to tolerate revision surgery or choose not to have a revision. These failures continue to count as a “successful” implants according to registries. Older patients have a much higher rate of dying within 10 years, therefore positively biasing the implant results. Diagnosis may also be a major source of age bias. Most older patients have osteoarthritis, while many younger patients have more complex conditions such as osteonecrosis, dysplasia, and posttraumatic arthritis, which all are known to have worse outcomes with THR (negative bias for hip resurfacing). It is therefore critical to examine the age of patients in any report on THR or hip resurfacing. Younger patients are more challenging. Implant survivorship achieved in older patients simply does not apply to younger patients. Most THR surgeons purposefully ignore this fact when they recommend THR for younger patients and quote them implant survivorship based on a much older group of patients. Benchmark registry implant survivorship for mean age 70 patients is 95% at 10 years. For patients under 50, it is 83% at 10 years and 50% at 20 years. My hip resurfacing survivorship is 99% at 17 years for any age and any diagnosis. THR doesn’t even come close.
Which is better for your general health/life expectancy?
Patients with hip resurfacing have at least a 25% lower 10-year all-cause mortality than THR patients.
What does this mean? People of any age have a defined statistical chance of dying within 10 years. Insurance companies have developed these types of life expectancy tables for various populations. Of course, the 10-year mortality rate goes up with age. Data from the British and Australian Joint replacement registries have been combined with national mortality databases to evaluate the 10-year all-cause mortality of THR and Hip resurfacing patients.
When controlled for age, sex, general health status, and even socioeconomic status, hip resurfacing patients have at least a 25% lower 10-year mortality depending on the study. There are now 5 published scientific studies that demonstrate this effect. "Thought leaders" in THR continue to ignore this data and persist in performing THR in young patients. If the data had shown the opposite, I suspect that THR proponents would immediately claim that this was evidence that cobalt ions released from hip resurfacing implants were poisoning people.
The most important conclusion I make from these studies is that low levels of cobalt release are likely not harmful to people in the long run. It is even possible that low level cobalt “supplementation” by these implants has some type of health benefit. The well known biological principle of hormesis states that some elements that are damaging at high levels are actually health promoting at lower levels. The case of free radicals and poorly conceived Vitamin E supplementation is only one example. But the best explanation of these findings seems to be activity. Patients who have hip resurfacing have been shown to be able to exercise more vigorously. Regular vigorous exercise has been shown to be the second most important lifestyle choice (after a healthy diet) that will affect health and longevity.
It is also possible that patients who seek out hip resurfacing are a group that is more interested in resuming vigorous exercise. A patient that is not highly motivated to exercise may be more likely to accept a THR recommendation from a local surgeon. Those who wish to resume vigorous exercise may be more likely to question the THR recommendation, do some independent research, and travel to a specialist surgeon who performs hip resurfacing. But one of the mortality studies mentioned previously did control for health status (Charlson comorbidity index). It is still conceivable that this index may not be fully able to capture a patient’s commitment to exercise.
Is failure due to wear debris/metal ions a problem?
Metallosis from hip resurfacing is rare, trunion corrosion in THR is much more common. Internal allergy to metal is a myth. Cobalt toxicity is very rare.
Metallosis from excess bearing wear (Hip Resurfacing)
Excess wear debris from metal-on-metal bearings can rarely accumulate to a point where serious tissue inflammation leads to pain requiring revision surgery. I call these Adverse Wear Related Failures (AWRF). Other terms with similar meanings are Altered Local Tissue Response (ALTR), Adverse Response to Metal Debris (ARMD), Acute Lymphocytic Vasculitis Associated Lesion (ALVAL), metallosis, or Pseudotumor (false tumor). All of these imply some degree of inflammatory tissue response to either wear or corrosion debris from implants.
Some experts believe allergy to metal particles may be involved. There is, however, no convincing evidence that an allergic response is occurring. 20% of people have skin sensitivity (allergic rash) to nickel. This skin reaction is much less common with other metals. Cobalt chrome alloy contains trace amounts of nickel. People with nickel skin sensitivity have no difference in THR outcomes than people who are skin test negative. Skin patch tests do not predict implant failures. No evidence supports that internal allergies to metals exist. The Lymphocyte Transformation Test (LTT) has been promoted to be an indicator for internal allergies but has never been successfully validated for this purpose. I tried to test this hypothesis but failed in a study comparing LTT tests done preoperatively to outcomes at 2 years after surgery. All artificial joint implants contain metal, there is no reliable test to determine if your body may tolerate one type better than another. In my LTT study 40% of patients tested “positive” for allergy to some metal in the implant. The most common “positive” allergy test was for titanium, which is present in virtually all THR implants. None of the patients that tested posive t any metal in their implant had any problem at 2 years. 3/135 patients had residual unexplained pain, all of these had a negative LTT. Metal allergy to implants is a myth.
Systemic cobalt toxicity (mild if cobalt >20ug/L vs severe if cobalt level is >>100ug/L)
Cobalt toxicity is a real but rare problem. There was a health crisis in Canada when cobalt was added to beer years ago. Cardiac failure occurred in some patients, but unfortunately, blood levels of cobalt were not reported. From other rare case reports of failed THR, it appears that a cobalt level well above 100 ug/l (perhaps over 500ug/L) is required to cause cardiac toxicity. Cobalt and chromium are both naturally occurring in our bodies, but very high doses can be problematic.
A normal blood level in most labs is less than 1.5ug/L. 80% of my patients fall in this range even with a metal-metal bearing. The mean level for my hip resurfacing patients is 1.4ug/L. Metal-plastic THR mean levels are 0.5ug/L, while Total Knee Replacement (TKR) mean levels are 3.3ug/L. If you are one of the nearly 1 million patients having a TKR in the US annually, you are more likely to have an elevated cobalt level than if you have a hip resurfacing!
There is some evidence that levels above 20ug/L may cause mild systemic toxicity in some patients. This includes neuropathy, tinnitus, and hearing loss, NOT cardiac failure. Unfortunately, these “mild” toxicity symptoms are very common for other reasons in aging people, therefore it is never clear if they are related to the cobalt level itself in any individual case. The best evidence indicates that these types of symptoms are most likely not caused by the blood ion level unless the level is over 20ug/L. I have used chelation with N-acetyl cysteine (NAC) rarely in patients with levels above 20ug/L without symptoms if the hip itself is functioning well. With a level above 20ug/L and systemic symptoms, I believe it is best to remove the implant. Although I have revised patients with metallosis (who have a mean Cobalt level of 70ug/L), I have not yet revised anyone for isolated elevated ions.
Adverse Wear Related Failure (AWRF) in metal-on-metal Hip Resurfacing.
The most significant problem with metal debris is a local inflammatory reaction to either wear or corrosion debris around the hip joint itself. Think of having dust blown into your eye. This causes severe inflammation, which is driven by the immune system, but it is not an allergic response to dust. All people’s eyes will become irritated to some degree. In the same fashion excess wear or corrosion debris can cause irritation of your hip.
In controlled laboratory wear testing, the metal-on-metal bearing of hip resurfacing releases the least amount of wear debris of any implant except for ceramic-on-ceramic THR bearings. A well-positioned implant will never fail due to the accumulation of excess wear debris (AWRF). However, if the socket component is placed too steeply or too tilted forward an abnormal wear pattern termed “edge loading” can rarely occur leading to AWRF (5% of sockets outside the established safe zone).
Irritation from excess metal wear debris results in a large fluid collection with thick white fluid resembling pus (but no bacteria are present). The wall of the fluid collection is very thick and permeated with grey metallic debris. There is almost never any damage to muscles or other vital structures.
The correct treatment is the removal of the fluid and careful excision of most of the cyst wall with the metal debris. And of course, correction of the faulty cup position or change to a different bearing type. Reports of damage to muscles or vital structures from AWRF in failed hip resurfacing cases are usually due to overly aggressive surgery. Those that believe in the allergy myth want to remove every bit of tissue and then the overly aggressive revision operation causes more harm.
A well-positioned hip resurfacing cup puts off less wear debris than most THR components in use today. However, if the cup is malpositioned, a small percentage (5%) will begin to edge-load and produce large amounts of wear debris causing a failure due to wear debris overload (AWRF). I began to understand this problem in 2007; by 2009 we developed a safe zone (RAIL) for placing the components as well as intra-operative x-ray techniques to assure the correct placement of the cup within the RAIL guidelines (Relative Acetabular Inclination Limit). Since 2009 (>5000 cases), not a single cup has failed to meet the RAIL guidelines, and no wear failures have occurred. Problem solved.
Trunion Corrosion in THR
But THR continues to have a major problem with trunion corrosion accounting for a 1-5% rate of failure by 10 years. Furthermore, in my experience, trunion corrosion results in much more severe soft tissue inflammation than occurs in a hip resurfacing bearing wear failure (AWRF). The THR problem with wear was solved with the introduction of crosslinked polyethylene 20 years ago. But the problem of trunion corrosion has now become a major source of concern. We do not fully understand this problem, nor do we yet have a solution for this problem.
The trunion is the connector between the head and the stem (hip resurfacing does not have this junction). Corrosion at this connector releases metal ions at a low rate but also something else that is very irritating to the tissues. The metal blood levels are typically mildly elevated. Severe inflammation and even extensive muscle damage can be seen. But similar metal levels are seen in many well-functioning hip resurfacing patients without any tissue reaction. Therefore, I suspect that the cobalt and chromium coming off the THR trunion in cases of trunion corrosion is NOT the source of the tissue reaction. Many THR surgeons think low elevated cobalt levels are the cause because they are unaware that well-functioning hip resurfacing patients often (20%) have mildly elevated levels.
With hip resurfacing I have had a rate of wear failure of 0/5000 since 2009, with THR the rate of trunion corrosion failure is 1-5% (50/5000) by 10 years. And THR surgeons claim that metal wear failure is the reason NOT to have a hip resurfacing? Instead, the risk of trunion corrosion is another reason not to have a THR.
Is there value in bone preservation?
Many patients just don’t like that their entire femoral head is amputated with a THR when it can mostly be preserved with a hip resurfacing.
From a non-emotional standpoint, it only matters if a revision is required. Therefore, this benefit is more important the younger you are. In patients under 50, THR has a 20% ten-year and 50% 20-year failure rate according to joint registry benchmarks which measure average surgeon outcomes. In the typical THR patient with a mean age of 70, the 10-year failure rate is only 5% in major joint registries. Therefore, the younger you are the more likely you need one or more revision surgeries in your lifetime.
Exactly what needs to be replaced in a revision depends on the failure mode. If only the socket needs to be done, then the amount of additional bone loss in revision is the same for a failed THR or Hip resurfacing. However, revision on the femoral side is much more involved if a THR stem needs to be removed. Often the top third of the femur needs to be split in half to extract the femoral stem.
If a resurfacing femoral component fails, cutting it off at the neck is the same that is done for a primary THR.
Hip resurfacing is less likely to require revision, and more femoral bone is retained to facilitate the revision surgery if it is required. Therefore, the younger the patient is, the greater the advantage to have a primary hip resurfacing.
Candidates for Hip Resurfacing
Most patients with severe hip arthritis will have better outcomes with hip resurfacing than if they chose THR. I can technically perform hip resurfacing on most of these.
Frequently patients who consult me with regards to hip resurfacing tell me that they have been told by another surgeon that they are not a candidate and that their only option is a THR. Don’t trust any opinion on this topic unless the surgeon does at least 100 hip resurfacings a year. Even among very experienced surgeons who have done over 1000 cases, I am much more likely to perform resurfacing on most patients.
Most patients with a severely arthritic hip are in fact, good candidates. In the early days of hip resurfacing, it was clear that young men had the greatest success. Now after 23 years of scientific study and perfecting the art of hip resurfacing, most patient groups have similar outcomes, and they far surpass what is published for THR. 99% 17-year implant survivorship applies to virtually all patient groups: men/women, young/old, good/poor bone quality, osteonecrosis, dysplasia, bone loss/deformity.
If a surgeon tells you you are not a good candidate for some reason, please formally consult me. I can do hip resurfacing on most patients.
There are still some groups (representing < 1% of patients under 65) who are NOT good candidates:
- Lots of pain/ minimal objective findings of cartilage loss. These patients have a high chance of dissatisfaction with any joint replacement.
- Extensive bone loss of the femur (>half the head), or socket. Cases with up to ½ head loss can be done successfully with uncemented femoral implants plus bone graft. I have done extremely severe socket cases in the past with custom implants, but currently, they are not available due to the FDA bullying of implant companies. In my analysis, the laws regulating the use of custom implants allow these cases, but the FDA pressures implant manufacturers not to supply them.
- Elderly patients with osteoporosis
Why don’t more surgeons perform this operation?
Because they are technically unable and/or they are still gripped by the metal "fear factor" promoted by THR "thought leaders".
This is a very good question. I have been performing hip resurfacing since 1999 and have moved nearly completely away from doing standard THRs. Over my career, I have performed several thousand THR, but have now performed more than 7000 hip resurfacings and have come to prefer this operation for most patients with a severely damaged hip. Annually I may do over 400 hip resurfacings and less than 30 THR.
As I have gained experience with hip resurfacing, the outcomes in all patient groups are so much better and the failures are far fewer than I can achieve with THR. Initially, hip resurfacing was an operation that worked best in young men, but with time I have improved the technique to the point where all patient groups have a 99% 10-year implant survivorship. This means that already 10 years ago I was doing better with this operation in all patient groups than anyone can do with a THR.
The main problem for other surgeons is that this operation is much more technically difficult to perform. But more than 30 surgeons in the world have mastered it and can achieve excellent outcomes. The international resurfacing study group that I was part of demonstrated that hip resurfacing is a generalizable skill that other surgeons who dedicate themselves to this operation can develop. Nevertheless, many of these skilled resurfacing surgeons are still reluctant to perform this operation in certain groups of patients.
All skilled resurfacing surgeons offer this operation to men under 60 with osteoarthritis (OA), because the best implant survivorship has been demonstrated in this group; but women, patients with small bearing sizes, dysplasia, osteonecrosis, and older patients are still controversial. As mentioned, I have overcome these problems at least 10 years ago and prefer Hip resurfacing in all these patients.
However, many skilled THR surgeons have tried their hand at doing a few hip resurfacings and have subsequently given up because they could not achieve the same results as they could for THR. I think it takes at least 500 cases for an above-average THR surgeon to become proficient at this operation. In those initial cases, if surgeons with excellent technical skills stick to young men with OA, they can likely do better than they could do with THR. But, on the other hand, there are likely many surgeons who just are not good enough to pull it off, no matter how much they practice. After all, not all highly skilled NBA stars can compete with LeBron James. Just as in sports, in surgery, some are just inherently more skillful.
The other problem is the time commitment. For the beginner, hip resurfacing may take 3 hours, and the surgeon is exhausted. Meanwhile, he could have done an anterior THR in 45 minutes for the same reimbursement. My average time for a posterior THR or hip resurfacing is the same at 90 minutes. I also do not accept the very low fees offered by the government and some commercial insurers, because I do not do a 45-minute anterior THR.
Unfortunately, there is no higher reimbursing code for hip resurfacing, which is a more complex procedure with better outcomes. This is why I do not agree to contracted rates with the government plans and many insurers.
The other factor is the problem with metallosis. An exceedingly high failure rate (50% within 5 years) was seen for the notorious DePuy ASR THR system. This was a metal-metal THR. Even the hip resurfacing version of the ASR had a scary (30% 5-year) failure rate. This was a terrible implant approved by the FDA which has soured most surgeons on the idea of metal-metal bearings. Depuy is a very popular brand worldwide, and many DePuy surgeons implanted the ASR and were burned badly.
Hip resurfacing solved the dislocation problem, but surgeons were scared to try this more complex operation. The beauty of large metal-metal bearing THR is that these implants also solved the age-old dislocation problem of THR (still the #1 failure mode of THR) and were no more difficult to implant than any other THR. With the ASR, loosening, metallosis, and trunion corrosion problems, unfortunately, were very common and were not predicted in laboratory testing and the FDA clearance process before general release. This has been by far the single largest orthopedic implant disaster that I have witnessed in my career.
Large metal-metal THR versions of other manufacturers also had a somewhat higher failure rate than metal-plastic THR due chiefly to trunion corrosion. They have all been removed from the market. None compared to the magnitude of the ASR problem. Most surgeons erroneously concluded that the metal-metal bearing itself was the problem. Aside from the ASR, trunion corrosion was the main problem with the other brands. It turns out that when a very large cobalt chrome head is attached to a small titanium stem trunion, the forces driving corrosion are very high. If a smaller cobalt chrome head is used (as in standard metal-plastic THR) corrosion failure is much less (1-5% by 10 years), but the hip is unstable due to the unnaturally small bearing size. This is an ongoing dilemma with all THR.
Hip resurfacing does not have a trunion to corrode, but THR surgeons still claim metallosis is a high risk for hip resurfacing because they maintain that the bearing itself is the problem. Meanwhile, we have learned that abnormal bearing wear causing metallosis only occurs in hip resurfacing if the acetabular component is malpositioned. I have published a safe zone for placing the component and have demonstrated that we can reliably place the socket into this safe zone 100% of the time and that this completely prevents metallosis.
I have not had a single case of metallosis since 2009 in over 5000 cases. THR surgeons simply are ignoring this published data and continue to claim that metal-metal bearings cause metallosis in a high percentage of cases randomly. Based on the disastrous ASR experience, I can understand their fear. But I have solved the minor metallosis problem with hip resurfacing. THR trunion corrosion continues to result in 1-5% failures by 10 years in THR. Trunion corrosion results in a far more severe inflammatory process than metallosis from abnormal bearing wear.
Metal-metal resurfacing can cause metallosis if malpositioned. THR can result in trunion corrosion in 1-5% by 10 years, randomly. We suspect that ceramic heads are less likely to do this in THR, but the data is not in yet. Most surgeons including myself are using ceramic heads in THR for this reason.
If you are old and if walking on the beach or golfing is what you consider an “active” lifestyle, a THR will get you out of pain and restore these activities. It is probably also going to last your lifetime. But if you are young and want to play impact sports, hip resurfacing is your best option.
But for all patients, a hip resurfacing is more likely to feel like a normal hip, to be stable (avoid dislocation and restrictions), and last longer. I challenge other joint replacement surgeons to equal my hip resurfacing outcomes with an old-fashioned stemmed THR.
I challenge you to find better-published outcomes.
- 99% 17-year implant survivorship for any age, sex, or diagnosis.
- 98% rate of satisfaction
- 0.3% dislocation risk, 0.1% revision rate for recurrent instability.
- No wear corrosion failures in over 5000 cases since 2009.