Hip Resurfacing News

Mr. Bloomfield responds to the The Times Article: "Is hip resurfacing the best  solution for arthritis?"

Let's start at the beginning!

Fact No. 1 : Nothing is as good as nature's own. Nothing can ever replicate the perfection of your native, original hip - before it became diseased. One day, maybe we can grow you a new one, then this debate will be irrelevant. Everything else is a compromise. Some compromises are better than others, and it depends on the individual patient, their activity or age, as well as the experience of the surgeon and the quality of components used.

Fact No. 2: However you 'spin' it, Conventional total hip replacement or THR is effectively an amputation of the head & neck of the femur. No if's and's or but's. Once it is gone, that's it, no going back. So, even if hip resurfacing [I call it BHR as I only use the Birmingham device] has a SLIGHTLY higher failure rate than THR, it is still worth thinking about the preservation of your femoral head & neck. The younger or more active you are, the more important this thought becomes.

Fact No. 3: The article only looks at revision rates when comparing BHR to THR. It says nothing about other, more subtle problems with THR like dislocation. OK, dislocation maybe rare with THR and almost unknown with BHR, but it is still a great concern in the early recovery phase. The fear of dislocation with THR drives the rehabilitation in the first few weeks and greatly restricts the advice the surgeon can give patients. Patients have to be given guidance to avoid dislocation which is often more onerous than is strictly required so that everyone can 'cover their backsides' so to speak. With BHR, my team is now [or should be!] telling MOST patients there are no special or onerous restrictions. Patients can sleep on their sides. They do not need raised toilet seats at home. They do not need to worry about dislocation because it is almost impossible. It allows the patient to recover full range of motion earlier and more safely. Unless there are concerns about bone quality, patients can be told to get back to activities of daily living as fast as their body allows. The only thing we have to be a bit cautious about is high impact stuff like running or jogging, football, rugby, skiing and the like. These can be allowed after the 3 or 4 month x-ray and if surgeon is happy that the danger of neck of femur fracture has passed.

The other, very subtle and impossible to quantify downside of THR is that surgical invasion of the femoral medullary canal forces marrow contents into the bloodstream. The bone marrow of the long bones is where your body makes all your blood cells. Red ones, white ones and platelets. It is why dogs love the marrow of a bone so much - it is rich in fat and protein. Forcing this marrow fat, rich in immature blood cells and other proteins, triggers an inflammatory cascade in the leg around the whole length of the femur and in the lungs which filter the globules before they would enter the circulation to the brain or other major organs. When severe, this phenomenon is called fat embolism. BHR dramatically reduces this embolisation phenomenon and is why I feel quite happy doing bilateral BHR when the patient has bilateral disease, but I would be very, very careful or wary of bilateral THR on the same day. In fact I tried bilateral THR several times before BHR came along and had lots of trouble. Done over 30 cases of bilateral BHR now and never regretted it. A truly astonishing operation as patients take only one or 2 more days to go home as compared with a single side BHR. i.e the recovery time is not doubled.

Fact No. 4: Some of us have always instinctively realized this, but BHR is exquisitely sensitive to accurate component positioning, and the exact metallurgy/manufacture of the components. THR can be put in quite sloppily and still work. At least for more than the 3 years the Times article is looking at. The figures in the UK National Registry are for all surgeons, using all the currently available hip resurfacing prostheses in varying mix. One should look ONLY at high volume, experienced surgeons to get the true picture. I wish I had the time and energy to look in detail at my own series, but it is certainly less than 4% failure at 3 years! The other trouble is that McMinn has already published large, detailed series so does the world need yet another one? McMinn's own figures, particularly in the under 55's are so good, many thought he must have fabricated them. I think less than 1% 'failure' at 5 years, not 3 years. This is the problem with raw statistics: they are so easily used like a drunk man uses a lamppost - more for support than illumination.

So much of the 'failure' we are looking at is due to poor surgery, poor prostheses or a combination of both. Women are only more at risk because their hips tend to be smaller, therefore the precise positioning of components is more critical. Women also tend to naturally have slightly weaker or less dense bone than men, so their cups may not integrate as planned or they may fracture through the neck of the femur. Apart from that, I personally don't believe there is any great gender difference.

Fact No. 5 ALVAL or metal ion 'allergy' is very, very rare. Irritation from excessive metal wear from poorly positioned or poorly manufactured prostheses accounts for the vast majority of the so-called ALVAL being reported. It sounds to me like Andrea had excessive metal wear leading to predictable irritation, fluid accumulation around the hip, and pain. Andrea, I do not think you had true ALVAL. Indeed your surgeons tend to confirm this as they did not find the masses of inflammatory tissues and destruction that would have been present if you had true ALVAL. The Melissa test is useless for predicting who will get ALVAL. The Melissa test has been used to justify large scale extraction of dental fillings from people, particularly in Scandinavia, on the basis that allergy to the metal in the fillings was making these people ill. Mass hysteria on a quite fascinating scale, and remember for very tidy profit. ALVAL is not confined to BHR. It is a problem with any metal-on-metal bearing couple. If ALVAL is used as a reason to discredit BHR, then all metal on metal bearings would have to be suspect. Which would leave only metal or ceramic on polyethylene, or ceramic on ceramic.

So lets look at metal or ceramic on polyethylene. Polyethylene is basically like hardened wax. Soft and slippery. Under pressure and when heated, it deforms or flows, just like melting wax. You can make the wax a bit harder, but it is still wax. There are constantly new or improved polys on the market. We have been here before. Let's look at Hylamer, a trade name from De Puy:

Hylamer polyethylene was introduced in the 1990s as an alternative to conventional polyethylene. Its chemical and physical properties, and especially its high crystallinity, were claimed to improve resistance to wear. Initially Hylamer devices were sterilized by gamma radiation in air, then the technique was changed and gamma radiation was performed in the absence of oxygen. Clinical experience has shown the early loosening of some devices made from Hylamer.

The text understates the problem. Hylamer was an unmitigated disaster and has long ago been withdrawn. So I don't trust poly in any shape or form FOR YOUNG ACTIVE PATIENTS. I still use it for the more elderly and sedentary. It still works perfectly well in this group.

What about ceramic-ceramic? This is the best alternative if you cannot have metal-metal for any reason. BUT some ceramic hips squeak. So loudly they can be heard across a room full of people. Ceramic is brittle and although ceramic fracture is now rare, it still happens and is under-reported. Ceramic ages or oxidises in the body and this can then lead to higher wear rates as the ceramic surfaces lose their shine or surface finish. Finally ceramic-ceramic is a very 'hard' bearing couple with no 'give' or shock absorption. BHR will, in most situations, have a thin film of fluid which can be displaced to absorb shocks at bearing interface.

So, in summary: Yes, BHR will likely ALWAYS have a very slightly higher revision rate than THR at 3 or 5 years, when comparing like for like in terms of young active patients. But the increased risk should be of the order of 1% or less, in the hands of an experienced surgeon. Not the 7 to 14 times quoted. It is the 30 or 40 year comparative results that will tell a different tale!

BHR revision, if ever unfortunately required, will always be easier than THR revision. Pity the poor patient whose THR fails early, or even later, particularly if the femoral side needs to be redone - their surgeon has a much tougher job on his/her hands. And abandoning BHR in favour of THR would mean abandoning all the more subtle advantages of an anatomical-sized component sitting on top of your own preserved femur.

We need to focus on precise surgery, good patient selection, the very best metallurgy and manufacture, not scare ourselves into abandoning the most revolutionary development in the field of hip arthroplasty in the last 50 years.

Mark