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BRITISH BROADCASTING CORPORATION
RADIO SCIENCE UNIT
CASE NOTES
Programme No. 5 - Hips
RADIO 4
TUESDAY 05/06/07 2100-2130
PRESENTER:
MARK PORTER
CONTRIBUTORS:
JOHN SKINNER
PETER KAY
IAN PALING
PRODUCER:
JOHN WATKINS
NOT CHECKED AS BROADCAST
PORTER
Hello and welcome to a special edition of the programme dedicated to hip replacement.
FACTORY FLOOR NOISE
Over the next half hour I'll be finding out about the challenges involved in manufacturing artificial hips, as well as the latest thinking on the various types.
What are the pros and cons of the newer resurfacing techniques, compared to the more established total hip replacement. Who is likely to fare best, with what?
And I'll be putting some of the issues and concerns that you have sent in over the last week to my two guests: John Skinner is consultant orthopaedic surgeon at the Royal National Orthopaedic Hospital in Stanmore. And we are joined by Peter Kay who is in our Cardiff studio. Peter is consultant orthopaedic surgeon at Wrightington Hospital in Lancashire - which is where the late John Charnley developed his famous technique for total hip replacement.
John before we start debating who is likely to benefit form what sort of new hip, and when. Why do so many people need new hips in the first place?
SKINNER
Well the commonest reason is osteoarthritis, which is a condition characterised by pain and stiffness in the hips. It's a condition that gets more common as we get older, as we get heavier and currently in the United Kingdom people are living longer and becoming heavier. There's also a second group of patients who have problems with their hips either from birth or in childhood where the hip hasn't developed completely normally and therefore the hips that perhaps don't have such deep sockets or they're slightly malorientated tend to wear earlier, so we have a second group of patients who have very disabling pain and stiffness at a much earlier age.
PORTER
So they've got some sort of inherent design fault that means the joint wears prematurely.
SKINNER
Exactly right.
PORTER
But does it make any difference what sort of lifestyle I follow, I mean this thing about you know if I'm a marathon runner or very aggressive sportsman am I likely to wear my joints out earlier?
SKINNER
I think what you find as people exercise more and do more running people who have congenital variance in their hips are more likely to wear them out much quicker, such that they are stopped from exercising, often in their 30s and 40s and become very symptomatic such that they can't live the life that they're looking to lead.
PORTER
So the sport's not causing the problem it's just accelerating or highlighting a problem that's already there?
SKINNER
I think that's true and there's good evidence that exercise is good for joints and it helps their lubrication and the nourishment of cartilage but if there's an inherent weakness it will wear it much quicker.
PORTER
Peter, could you outline key structures involved in the hip?
KAY
Certainly, I mean a hip joint's really a ball and socket joint, consisting of a perfectly round ball seated in a socket. Unlike say your knee or your elbow, that moves in one plane, the hip can move in all directions. Now one of the most important structures in the hip joint is the articular cartilage, the smooth covering that covers the bone but allows the ball to glide within the socket, and it's that smooth covering that gets damaged in osteoarthritis and other forms of arthritis as well. There's some large muscles that operate the hip joints, one of the biggest muscles in the body act as levers around the joint and when we lift ourselves up out of a chair or walk up to three times our bodyweight passes through the hip joint. And without the muscles contracting around the hip joint we tend to limp and with arthritis we get pain and with pain this inhibits the muscle contracture and that stops the hip working.
PORTER
Peter, how long have surgeons been operating on arthritic hips?
KAY
Well there's reports of surgery being performed on arthritic hips going back before the beginning of the last century. And initially people tried to use materials such as ivory and glass. But it was really perhaps in the late 1950s and early 1960s that we saw the emergence of more modern hip replacement, where we replaced the socket with a plastic socket that was fixed in with cement and we replaced the upper part of the femur, the ball part, with a metal ball. And one of the people that really promoted this and really developed modern day hip replacement was Sir John Charnley, who developed the technique at Wrightington Hospital. But it wasn't all easy sailing, there were some difficult problems initially until we sort of arrived at the type of joint that we now see in current usage.
PORTER
Well we've covered what goes wrong. And what needs replacing. But what should it be replaced with?
British company Corin Group manufactures a range of artificial joints, and is one of the pioneers behind the latest hip-resurfacing techniques. Very high tech it may be, but their factory in Gloucestershire sounds and smells much like that of any other engineering company. Ian Paling is Corin's Chief Executive.
PALING
Where we are standing now it's a manufacturing cell specifically for the socket component of the resurfacing hip. And you can see that is a matt grey colour, it's a casting ...
PORTER
It's shaped like the top of an ice cream cone.
PALING
Yes it is. We take this device and then carry out a series of operations to it. The very first operation we'll do is to put this on a computer driven machine which will actually take off this surface layer of metal and create the initial dimensions of the device.
PORTER
Ah now here we are, now here's our dull grey cornet that's now turned into something that's bright and sparkly here.
PALING
There you go, you can see there's been initial machining on this to create this finish here.
PORTER
And the inside is absolutely smooth. Is that the finished product there?
PALING
No, no, no that's far from the finished product, that's creating the initial dimensions.
PORTER
How do you know that there aren't any flaws in the casting to start with, I mean are these examined with x-rays or ...?
PALING
Yes they're qualified by a manufacturing source, they look at every casting using x-rays, as you say, and they can see there are no flaws. And when we manufacture the device each device goes through 100% inspection, so we're looking at the motion of the actual device, we're looking at the surface finish, make sure there are no scratches. Having done that it then goes through a gamma ray sterilisation. So when the product ends up in the hospital it'll be securely packed in a double pack process actually and it will be completely sterile.
Well here's a conventional hip and you can see it consists of three components: there is a metal stem which goes down the shaft of the patient's femur; there's a modular head, which is the same material ...
PORTER
That's the ball.
PALING
That's the ball, exactly, the ball and socket joint and that articulates against a polyethylene component which fits into the bottom of the patient's [indistinct word]..
PORTER
So that's the socket that goes in.
PALING
Exactly, that is the conventional ball and socket and actually that device works extremely well in the elderly inactive patient and has been around for many, many years and has got excellent clinical results.
PORTER
So compare and contrast that to the resurfacing hip that you've got here because this involves obviously removing the whole existing hip - patient's hip - cutting the ball off the top and replacing it with this metal stem. With resurfacing what happens?
PALING
Well let me try and explain what the problems are as I see it with the conventional hip, particularly for the younger more active patients. If you take a conventional hip the problems are really threefold: firstly, as the hip articulates so polyethylene debris is created ...
PORTER
The metal literally sharding off pieces of plaster.
PALING
Exactly, it wears away the polyethylene, which gets into the joint space, that causes a condition called osteolisis which eventually will cause the joint to come loose. Now the younger more active the patient is the quicker this process happens and therefore whilst you can expect a conventional hip to last quite a long time in elderly patients, in younger patients you almost certainly will have this osteolisis reaction. So that's the first problem. The second problem is that with a conventional artificial hip like this has a small diameter modular head and you can see this particular one is a 28 millimetre modular head ...
PORTER
So that's about an inch, that's the ball ...
PALING
Exactly, it's just over an inch in diameter. And the small diameter there minimises the polyethylene debris but it creates another problem which relates to range of motion. And the range of motion on this device is quite restricted, so if a patient wishes to do any form of extreme sports or anywhere where the range of motion maybe exceeded this will pop out, it will dislocate and clearly cause great pain and discomfort to the patient and will require a hospital visit. The third problem, as you said earlier, is that actually with this device what you're doing is you are resecting the femoral head, so you're cutting the femoral shaft off, getting rid of good neck and good bone because it's only the cartilage that's worn away, and you're putting a large piece of metal into the femoral shaft. So it's a fairly invasive procedure. Now those are the three problems associated with the device and we looked at each of those and developed this device which is called a resurfacing metal-on-metal head and the first embodiment of this was in 1989, so it's not a new technology but it's recently in the last five years where the technology's been very rapidly accepted by surgeons worldwide.
PORTER
Now the first thing that's obvious to me looking at that is that the ball part is three or four times the size.
PALING
Yes exactly and that's one of the key issues. The first thing we've done is move the polyethylene and that was absolutely fundamental because polyethylene is a compromise in the joint, if you can take that away then you eliminate this problem of osteilisis and therefore loosening. So what we've done here is created a metal-on-metal articulation and this typically - I think this is about a 50 millimetre head - so one and half times the size of that. But most importantly or as importantly it's a very conservative procedure because rather than chopping the patient's femoral head and femoral neck off you're merely reshaping the femoral head, putting this on as a cap and creating the same articulation with a metal-on-metal articulation.
PORTER
So a simple way might be to describe it: it's like wearing a solid shower cap over your head, it sits over the top.
PALING
Exactly, it just sits on the top of the bone, preserves the femoral bone and therefore is very conservative. The average age of implantation of this hip for us in the UK is 48 years old, so it is a young patient grouping we're looking at who place large demands on that hip. And many of them are active, they want to carry on running or playing golf. I mean we've got one individual who has two of these in who has just completed a polar marathon, which sounds like quite staggering, but ...
PORTER
Even with good hips.
PALING
Even with good hips, absolutely.
PORTER
Ian Paling. You are listening to Case Notes, I'm Dr Mark Porter and I am discussing hip replacements with my guests orthopaedic surgeons Peter Kay and John Skinner.
Peter, Ian Paling is obviously a resurfacing enthusiast - not surprising given his company helped develop the technique. You on the other hand come from the hospital where one of the most popular full replacement hips was developed: The Charnley hip. What do you think, in brief, of the new kid on the block?
KAY
Well there are lots of different types of hip replacements out there. I mean the National Joint Registry in the United Kingdom shows that there's over a hundred different hip replacements to choose from. I think one must be very careful and look - when people are looking at new developments - to make sure that we are really confirming benefit to our patients. I mean one of the things I would take slight issue with the various young mothers I've got who've got conventional hip replacements and people that perform heavy manual jobs, they're certainly not the old and inactive that have been described. Many patients that have conventional hip replacements are quite young and are very active. And I routinely see patients in one of my follow-up clinics where patients have had hip replacements in for 30-40 years who were obviously quite young, perhaps in their 30s and in their 40s when they've had them performed. So whilst it's true to say that with conventional joint replacement there can be problems with time, things can get worn, that's also true of every form of hip replacement including resurfacing, where at some point in the future we may well see problems developing.
PORTER
I want to come back to the longevity issue a little later on. John Skinner - you are a little bit more of an enthusiast, you actually put resurfacing hips in yourself?
SKINNER
I do, I think - I think it certainly has a role, which is becoming clearly defined, in young active people. What we know, whatever hip replacement, as Peter said, it will wear out eventually, as any artificial bearing will. And there are some theoretical advantages of resurfacing. It may not be entirely intuitive if you wanted to replace the hip to start by cutting off the ball and throwing away a good piece of bone. By resurfacing, should the hip fail in 15, 20 whatever years time, then the revision is technically likely to be much more simple. And therefore you could remove the ball with the resurfacing cap on it and then fix a stem into the femoral canal, as is done with a conventional hip replacement, and it's always much easier to fix into bone that hasn't been used before because once stems become loose they damage the bone and make subsequent fixation more difficult. So certainly there are some advantages. The metal-on-metal articulation, it's the engineering that has improved dramatically which allows us to polish these components to a very high tolerance so that large diameter balls, which are inherently more stable, can perform to a high level with low friction.
PORTER
Let's continue the debate with listener Liz Robert's story.
ROBERTS
My hip problem's started really in my late 30s and in fact by the time I was 40 I was unable to play tennis or ski because of the pain. And I think I was about 44 when I first met the orthopaedic consultant. He x-rayed my hip and could see that I was in considerable pain but because of my age I couldn't be considered for a hip replacement. And so it went on really until I read about a hip resurfacing operation. And that it was particularly useful for younger people because hopefully it would not need to be redone. And it was just such a successful operation for me. I had to work very hard at physiotherapy because I'd had such pain for such a long time, the leg muscles were severely wasted. But with physiotherapy that all came back and now I live an extremely active life.
PORTER
Liz Roberts. Two points I want to pick up on there. Firstly at 44 she was told that she was probably too young for a total hip replacement, Peter why might age be an issue, you said earlier that you are doing them in people in their 30s and 40s?
KAY
Yes, I mean age is an issue because ultimately hip replacements - every hip replacement we've seen so far ultimately wears out and in the United Kingdom, particularly with women, women live a long time - the average age survivalship tables tell us that women will live to 84, if you're in your 40s you may be looking at requiring a hip replacement to work over 40-45 years. I mean I replace hips in people in their early 20s and even in their teens. If the hip is damaged enough and if the pain is severe enough that there really isn't any other option. And the question is whether you want your mobility now, whether you can persevere for a bit longer. I mean if you can put a hip replacement off for say 10 years that might be a good thing to do.
PORTER
John Skinner, do you feel more comfortable offering hip resurfacing to patients who are younger because of the fact that it might be - it might be easier to revise it if they need it?
SKINNER
I think what we're seeing and what Peter's alluded to is that hip replacement was an operation for people who were just about to go into wheelchair. In the early days before we got confident with hip replacement it was left as a last resort. We're now very confident with hip replacement and subsequently with hip resurfacing and patients now are not prepared to put up with symptoms. And the philosophy of many people now is that I don't want to wait 10 years, I want pain relief now, I want to live my life now, I could be dead tomorrow. And I think that's something that we see time and time again. And so in answer to your question in the appropriate patients I'm happy with resurfacing because as you say I'd be more confident that I can revise it to another a very good hip maybe in their - if they're starting in their 40s, maybe in their 60s or whatever.
PORTER
Roma Henry had her operation done on the NHS earlier this year.
HENRY
I had a hip replacement in March but then when I went to have a look at the x-ray I thought oh that's not the resurfacing technique that I'd hoped for, that's a total hip replacement. And the consultant said well I don't know why you thought you were going to get resurfacing and I said because I'd asked for it about three or four times. And then he said no I don't do it for anyone, no female anyway, that's older than 55 and as I'm an ancient old soul of 57 I was too old for it apparently but I was annoyed.
PORTER
John Skinner, why the upper age cut off?
SKINNER
I think as you get older we already have perfectly good technology in the form of modern conventional hip replacement which will achieve all the - all the goals in someone who is older. I think it's always important to distinguish physiological age from biological age and there are some people who are very active. But one of the problems with hip resurfacing is there is an incidence of hip fracture or femoral neck fracture after resurfacing, it's not common, it's less than one in a hundred, but if you look at the group in where it's most common, it's most common post-menopausal ladies sort of beyond the age of 50s and getting into their 60s as the bone starts to get a little bit more osteoporotic and thinner.
PORTER
So this is a benefit/risk thing that in the younger patients the benefits are worth using, in an older patient the benefits aren't necessarily there over our existing technology, so why use something else.
SKINNER
Absolutely right, why use something that's got less of a track record when we already have a very good standard treatment which will do everything that they require of a hip?
PORTER
Peter Kay, how much influence would a patient's wish for a particular type of hip have on your choice of procedure?
KAY
Well at the end of the day I mean you've got have a very frank and open discussion with the patient. And I would never push a patient into having something they didn't want to have. I will often have a discussion with a patient, I will explain why I use a particular type of hip replacement I do and what the evidence for that might be. And if a patient wants a type of hip replacement that perhaps I don't do then I would ask a colleague perhaps who did do it to see them.
PORTER
Okay, now I want to go back to the subject of how long these hips might last. Helene Parnes is originally from Vienna but had her hip replaced here in the UK.
PARNES
I had my hip done 37 years ago in the Wrightington which is in Lancashire and it was very successful and of course Professor Charnley was the originator and I still have the same hip. And I'm really happy about it because now I'm 88 and I have no problems whatever.
PORTER
One very satisfied customer. She must have been one of the first to have had a Charnley hip Peter. What do you tell your patients about how long their new hip might last when you see them at that initial consultation?
KAY
Well we've got survivorship figures of hip replacements looking at patients that are under the age of 50 at the time of surgery, we know that about 97% of hips will still be working after 10 years, that falls to about 90% after 15 years and we know that over 75% of hip replacements are still working after 20 years. So I tell patients that really it's a statistical calculation, that there's not an absolute time, but most people can expect hip replacements to probably last them - conventional hip replacements - maybe 15, maybe 20 years. But there are some early complications that can occur that may result in premature failure of joint replacement, occasionally associated with infection or early technical difficulties. So I give patients a range and also explain that heavy more active patients, particularly say farmers, really seem to be able to wear out a hip replacement much more quickly than someone who's lighter who perhaps doesn't engage in as much activity. But many patients are very active with conventional hip replacements and they last many years. The lady who've we've just heard from, she's 88 now, must have been 50 when she had it done and that hip replacement has served her well for a long, long time and she's been probably quite an active lady.
PORTER
John, resurfacing hasn't been around for so long and therefore we can't say with the same degree of certainty of course how long it'll give problem free service but is there any reason why it shouldn't do at least as well as a total hip like the Charnley or perhaps even better given that today's engineering techniques must have advanced considerably since the Charnely hip was in - the initial thing was first devised?
SKINNER
Well the results with resurfacing are now out to about 11, 12 years with the originator surgeons in Birmingham. But there are series reported from independent centres in Australia and in Newcastle where there's very high success rates - of 97, 98% survival of the implant between seven and nine years. Now what you find is that patients that are between seven and nine years are doing exceptionally well, they have high function, they have high hip scores and radiological review doesn't show any cause for concern or any significant problems. So therefore you have to say that you expect many of these to go on and I think time will tell what the actual survival will be. But with resurfacing many of the problems tend to be in the first year and if you get beyond the first year they seem to do exceptionally well.
PORTER
We'll come back to some of those problems a bit later.
Sadly, not all operations go as smoothly as Helene Parnes. Sixty-five-year old Jim Hassey had a total hip replacement just over two years ago.
HASSEY
I realised after about six weeks things were not recovering as they should have been. I was badgering my GP for physiotherapy and that made certainly big improvements for balance and things like that but I've been left with just as much pain as before the operation and very much a weakened joint - I can't stand or walk for any length of time, I can't lift anything of any size, I can't carry anything. So it's really restricted my activities. I've seen the consultant recently and they explained that the operation itself seemed to have gone well, now he thought that I was extremely unlucky because he thinks there's less than 1% of people end up with this problem, which is muscular rather than [indistinct words]..
RAYMOND
My name's Nicole Raymond and I've had three hip replacements. The first one was in 1994 when I was 52 and during the operation they discovered that the hole down my thigh bone was smaller than they anticipated and so they pushed this pin in and split my thigh bone which was exceptionally painful when I came round. As a result of that I had four years of really misery - the left leg was then shorter than the other one and the foot stuck out at about 10 o'clock. Anyway I moved to the West Country and was sent to a revision's expert who in 1998 redid the whole operation with a whole new hip, he brought my foot down to meet the other one, it faced the right direction and the whole thing was absolutely wonderful. And three years ago he did the right hip as well and now I'm a new woman really, it's made my life so much different. I wouldn't want to put people off having hip replacements and I know some do go wrong but as I am now I'm fine and I can do all the things that I did quite some years ago with no pain at all.
PORTER
Nicole Raymond and Jim Hassey sharing their experiences there.
Peter Kay, whatever type of surgery you have it's a big operation and things can, and will go wrong. What do tell your patients about the likely outcome from an orthopaedic point of view and the risks that they face?
KAY
Well in general terms a hip replacement is one of the most successful procedures that is performed in terms of relieving pain and disability. But there can be risks. I mean the risks I tend to outline are the risks of infection, the risk of infection of hip replacement is somewhere between a half and one percent, though it depends how long you follow your patients for. If you get an infection in the hip replacement it sometimes has to be redone. There are technical risks, as we heard from the lady that was just talking about injuroperative problem, of damage to the bone, with early loosening of a hip replacement. There can be risks of damage to blood vessels and nerves around the hip joint. And the muscles sometimes don't function well, like your other caller, who described that his muscles weren't working perfectly. And there are general medical risks - are you fit enough to undergo the surgery. And of course the important one is that if we get through all the early risks, beyond the first year, then if a hip is going to last for a long, long time then it mustn't wear out and of course one of the things we do see after 15, 20, 30, 40 years are hip replacements that are now getting worn. And those are the general sort of discussions I have, there are other problems such as blood clots, which we give medication for, and then there's lots of small print, little risks, that can beset people. But the headline figure is that 98% of people that have a hip replacement at the end of the day do quite well from it.
PORTER
John, how quickly do they recover, if a patient comes in to see you, they're on the ward, how long might they be in hospital and how quickly might they get back to normal activity, assuming everything goes smoothly?
SKINNER
Okay. Following hip surgery the aim these days is to get them to stand and to start walking either the next day or later the same day, to start mobilising in hospital. And by five days the majority of people can get in and out of bed, in and out of the shower, walk, get up and down stairs and in and out of the car and by five days most people will be home after a primary hip replacement.
PORTER
And last but not least what do we know, very briefly, about the effects of alloys and cements being left in people for many years, is there any sign that these can be harmful?
SKINNER
Well I think what we know about all implants is that they're foreign materials, that with the metal-on-metal implants we know that the wear products are metal irons of cobalt and chromium, which are tiny, they're nano particle, much smaller than the conventional wear particles which were polyethylene, which were much bigger. And these, we know, do get into the bloodstream, we know that following metal-on-metal articulations you will have elevated cobalt and chromium levels but as yet, despite them having been used at various times since the '60s and '70s there's no significant evidence of a major systemic problem. Perhaps a small group of patients who have a local reaction to high levels of metal irons and get a sort of allergic reaction but this is exceptionally rare.
PORTER
I'm afraid we're going to have to leave it there, that is all we have time for. John Skinner and Peter Kay in Cardiff, thank you very much.
Don't forget you can listen to any part of the programme again by visiting the website bbc.co.uk/radio4 - where you will also find some useful links for more information on the issues that we've discussed today.
Next week I'll be learning more about the world's first cancer vaccine. It protects against the virus that causes cancer of the cervix and could soon be included in the UK's routine immunisation programme. But who should get it, and when? And what are the implications for the cervical cancer screening programme? If the vaccine is introduced will women still need regular smears? Join me next week to find out.
ENDS
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