Knee replacement surgery webinar transcript

Zoe Andrews

Okay, welcome everyone and I hope you're all well. My name is Zoe and I'm the Matron for surgery at Benenden Hospital.

I'd like to welcome you to our webinar on knee replacement surgery. You'll shortly be taken through a presentation by Mr Richard Goddard, Consultant Orthopaedic Surgeon. His presentation will be followed by a Q&A session and, if you'd like to ask a question, please do so by using the Q&A icon on the top right-hand side of your screen. This can be done with or without you giving your name.

Just to remind you that this webinar is being recorded. Although other attendees won't know that you're taking part, unless you give your name when asking a question, if you'd prefer not to be part of the recording, now is your opportunity to leave.

I'll hand you over now to Mr Goddard and you'll hear from me again shortly with your questions.

Mr Richard Goddard

Thank you, Zoe. Hello everyone at home and welcome to our webinar on knee replacement surgery. So just a brief mention of knee injuries before we get into knee replacements.

Obviously, knee injuries are very common during high energy sporting events but also, we need to remember that knee injuries can occur in routine daily life; slipping in the shower, walking the dog, things like that. Knee injuries are obviously very painful and, if you already have arthritis of the knee, can cause an exacerbation of the arthritic symptoms.

So, what should you do, following a minor knee injury? Well the obvious: rest, elevation, perhaps try an ice pack, simple medication – paracetamol, anti-inflammatory medication - if you can tolerate it, and if it doesn't settle down after a few days then obviously seek professional advice from your GP or one of the local hospitals.

So, onto the main talk of today's webinar - knee arthritis. Osteoarthritis is very common; it's one of the more commonly arthritic joints and knee replacement surgery more recently has overtaken hip replacement as the most common orthopaedic operation for arthritis. This slide shows on the left-hand side what the normal knee joint should look like and, once inside, the cartilage of the knee should be lovely and smooth - a bit like a billiard ball or looking at some highly polished china. It should be nice and smooth, not rough at all. This is the perfect articular surface for a weight-bearing joint.

On the other image, the arthritic knee on the right-hand side, we can see there's cartilage damage and arthritis is basically the process where the cartilage becomes microscopically frayed and then the cartilage starts to crumble away and you get potholes and craters in the knee joint, exposed bare bone. And it's this bone that's exposed that have nerve endings that then cause the arthritic pain. Severe arthritic pain is often caused by bone touching bone in the knee joint.

These are x-rays of patients and the left-hand x-ray shows the normal knee joint. I'd like you to notice the space in between the thigh bone and the tibia (the shin bone). The space there on the x-ray is full of cartilage. This cartilage is invisible on the x-ray, but it's appreciated from the space between the bones. The x-ray next to it shows an arthritic knee and we can see one side of the knee joint has no space there at all and all the cartilage is worn away. The knee is not straight anymore; it's gone deformed, it's bending to one direction. This person's going knock-kneed and they've got severe arthritis of their knee joint.

I'd expect this person to have severe pain with daily activities - pain walking - and this patient would be suitable to consider a knee replacement if their symptoms were indeed bad enough.

So, what causes arthritis?

We've said it's very common, but why does it occur? Well it occurs just due to normal wear and tear as one gets older. It becomes more common in people in their late 60s, early 70s and 80s, as opposed to people who are younger in their 20s and 30s.

Being overweight puts more load on the knee joints and this can cause arthritis to occur more rapidly, and in people who are younger than we expect. Previous injuries, sporting injuries, can cause damage to the cartilage - torn ligaments - and this predisposes the knee to early arthritis and would more likely see than normal. People who do physical work, manual work, people do a lot of walking, postmen etc. would put more wear and tear through the knee and are more prone to arthritis than people doing more sedentary, deskbound work.

Also other inflammatory conditions - mainly inflammatory arthritis, rheumatoid arthritis and gout - inflame the knee joint and predispose the knee to cartilage damage which, over the years, then leads to secondary arthritis.

So, what are the symptoms of arthritis?

Very early on, the symptoms may be very vague. You may just have some stiffness in the morning, pain perhaps after a long walk, pain on more strenuous demanding activities such as gardening, gentle sports that type of thing. You may feel the knee clicking, crunching, sometimes with instability, the knee may give way and some patients describe recurrent swelling.

Later on, as the arthritis gets more severe, it's very obvious then when someone's got these severe symptoms. They have severe pain, often pain at night, keeping patients awake is very common, pain just simply sat at rest reading the paper, watching TV, is again very common.

People notice - and often friends and family notice - that they're not walking properly, and their leg has become bowed and deformed and clearly people with a very arthritic knee can't walk very far. Some people struggle to walk around the house, others to walk short distances to the local shops.

This slide just shows the stages of arthritis and basically grade one and grade two arthritis is very mild, and we wouldn't necessarily rush into any major treatment for this. Things like activity modification, painkillers would be helpful. But then grade three and grade four, especially, the arthritis is becoming more severe. With grade four arthritis there's areas of full thickness cartilage loss and this is when major surgical interventions like a knee replacement could be considered.

So, what's the treatment of arthritis?

Non-surgical treatment should be tried first. Patients can try it themselves; GPs, physios should instigate this type of treatment and, clearly if one is overweight, then going on a weight loss program can be beneficial.

The normal knee joint takes a lot of force; standing from a chair and going up and down stairs. Seven times your body weight goes through the knee joint, especially the kneecap joint, going upstairs so any small amount of weight loss has great benefits on the forces going through the knee joint. And indeed, people who lose significant weight report their pain is a lot better

Activity modification is really saying: avoid the things that cause severe pain. I often get people with an arthritic knee who enjoy long distance running, half marathons that kind of thing and clearly avoiding these excessive activities would stop their arthritic symptoms before considering major surgery to treat their arthritic symptoms.

Physiotherapy works usually by strengthening the muscles and ligaments around the knee. If you have weak muscles around an arthritic knee, the pain is often worse and symptoms of instability and the knee giving way can be helped with muscle strengthening and physiotherapy. You should take simple analgesia; it's best to visit your GP to get the correct advice, as all medication does have side effects and interaction with other tablets, but simple things like over-the-counter paracetamol, anti-inflammatories (if you can tolerate them) can be beneficial prior to activity and when the arthritic pain occurs - and GPs can then prescribe more stronger painkillers if required.

Some people find strapping the knee or bracing the knee can be helpful, but we have to be careful that we're not causing the muscles to be weak by using knee braces all the time, so it's important not to brace the knee all the time and let the muscles do some of the work.  Knee injections can be considered, injections of steroid can help pain and swelling and there are injections of lubricants, which can also help the knee joint glide more smoothly. And that can correlate with a reduction in pain.

When all these measures fail, we consider operations. The most common operation for a severely arthritic knee is a knee replacement, but other techniques can be considered, such as correcting the deformity around the knee joint if it's not too severe and, occasionally keyhole surgery can be considered to remove loose bodies. If there's just a small patch of arthritis, then microfracture technique where we stimulate cartilage growth could be considered.

I've put a question mark next to cartilage transplant. This is very experimental and, I think clearly is the future, but at the moment isn't routine surgery and isn't a sensible treatment for a severely arthritic knee. But watch this space. In the years to come this may overtake the need to do knee replacements.

So, with a knee replacement what are the options?

You can replace the entire knee, which is a total knee replacement (the more common operation), or you could just replace part of the knee, commonly the inside or medial compartment or the patellar femoral joint (the kneecap joint).

At the bottom of the slide there we have constrained knee replacements, and these are for patients with severe deformity or people who've had a knee replacement which after 15 or so years has become worn and they need to have their knee replacement revised and re-replaced.

So, here is a model, and an x-ray of a simple knee replacement. We can see that this is a resurfacing replacement, so during the operation the surgeon will make an incision around 15 centimeters at the front of the knee, carefully cut through the muscles and ligaments to get into the knee joint and then surgically remove the arthritic surface - and then fix to the bone often with a surgical cement to adhere the knee replacement to the bone, a metal resurfacing (like a metal cap) over the thigh bone and on the shin bone there's a metal tray with a keel which gives some stability.

You can see on the x-ray there's space between the two white bits of metal, and this is the plastic which is the new articular cartilage.

So here, this poor patient has severe arthritis, severe bowing of the joint. This is due to a severely arthritic knee with severe contractures. And we can see the x-ray next to it that afterwards the knee is nice and straight. So, one of the goals of a knee replacement is to correct the deformity. Correcting the alignment obviously helps pain and mobility

Some people ignore their arthritic knee and what happens? Well, as the arthritis progresses, you begin to not only wear the cartilage, but you erode the bone. People have various reasons for ignoring their knee but this poor chap, he was scared of coming to hospital and left his knee far too long. And we can see he had this gross deformity; his ligaments were very unstable with bony erosion and he needed a more complicated knee replacement to sort the problem out

So mostly arthritic problems, no matter how severe, can usually be sorted out with surgical intervention. But as the operation gets more complicated it begets more surgical risk and the success of the operation with respect to movement and mobility goes down. So, it's better to catch the arthritic knee sooner rather than later - before we run into bony problems and ligament problems.

Rotating hinge knee replacements – I mentioned briefly - these are for a severely worn knee perhaps with major bone loss or people who've got bone cysts or tumours around the knee, people with severe deformity and people who require a revision knee replacement where the first one was worn away after a number of years.

Very occasionally people can dislocate a knee replacement and then clearly you tear the ligament so, after you've had a knee replacement, you need to be very careful. Do the exercises, build up the muscles - knee replacements are not indestructible, they need to be looked after and you need to take care with activities that you do.

If someone dislocates a knee replacement, then that's a significant problem, and often requires surgical intervention again to correct it.

So, what do we try to achieve with the knee replacement?

Well clearly for the patient, we want to cure the arthritis, cure the pain, increase their daily activities and get them doing the activities they enjoy doing.

From a surgical point of view, I like to correct the deformity. We're trying to get the individual's mechanical axis to be exactly what it was when they were presuming it was normal. This leads to then better longevity of the knee replacement and usually a better outcome with respect to range of movement and stability and function.

If a knee replacement is malaligned then a lot of the time it doesn't cause a significant problem, but if a knee replacement has severe malalignment due to poor surgical planning or poor surgical technique, then catastrophic failure of the knee replacement can occur.

This is an x-ray which shows just that the knee replacement was malaligned and subsequently, after a few years, the knee replacement failed, and this would then need one of those hinge knee replacements that we saw a few slides ago.

So, it's really important with the knee replacement during the operation to plan it correctly and get the alignment as accurate as possible.

Why are surgical techniques changing?

I see patients getting younger. When I was a junior doctor, training, patients having knee replacements usually were in their late 60s, early 70s. Now I operate on patients from a whole range of ages from their 40s to their late 80s and occasionally people in their 90s if they're medically fit but I'm seeing more and more younger people with knee arthritis, requiring major surgery and this puts great demands on the knee replacement that I do.

People (rightly so) have greater expectations of what they want to do when they retire. People want to go skiing, do long walks, do more excessive activities than people did, say, 30 years ago and all of these activities put more pressure, more wear and tear, on the replaced knee, so it's increasingly important to get the alignment as accurate as possible. This is one of the advancements in knee replacement surgery; it's been around for a number of years now but is routinely used here at Benenden. This is the Signature knee replacement.

What is Signature?

Well in normal knee replacement, we use a clinical examination of the patient's knee and then plain x-rays to work out the deformity. The idea of Signature is to make this more accurate.

We use an MRI scan to look at the mechanical axis and we're trying to put the knee replacement as accurately as possible in the limb to replace the individual patient's alignment and mechanical access; hoping that that patient will then have better function and be able to do more extreme activities if required.

So, unlike a normal knee replacement, we get x-rays but also MRI scans of the knee, the ankle and the hip joint and this enables a computer and the surgeon to work out that individual patient's alignment, which varies from knee to knee, patient to patient.

The scan is so sensitive that if you did the scan and didn't have an operation for, say, six to nine months we would probably have to repeat the scan prior to surgery because the alignment would have subtly changed.

A computer then helps the surgeon to analyse the MRI scan and we get a model of what that patient's arthritic knee looks like, how it's affecting the hip and the ankle. We get an idea of the deformity and the amount of bone that needs to be taken during the operation to correct the deformity.

So, the aims of this operation are obviously, to help pain, increase mobility but correct the mechanical alignment of the knee. This will then lead to better functionality of the knee replacement and that will then manifest as a better outcome for the patient, enabling them to achieve their expectations

That said, one part of the knee replacement is the operation - but the second part is the patient's motivation to do their exercises and to get the knee moving afterwards. So if you have the most accurately done knee replacement with Signature, but don't do the exercises required of you, when you go home in the first few weeks and months, the outcome of the operation won't be as good as someone who does the exercises religiously. So that's just as important: the physio, the exercises, the self-motivation as equally important as the operation.

So, Signature, after we've done the computer planning, is slightly less invasive than a standard knee replacement. We use metal jigs that are fixed to the bone during the operation which you do by drilling into the bone and passing metal pins which are removed. Signature simply uses these metal jigs, which are fixed to the bone, and this is less invasive during the operation so there's often less swelling, less bleeding afterwards.

But this is small print and knee replacement is still a painful and significant operation. This sort of can make recovery a little bit quicker. The result of this should be a nice, straight knee you can see on the x-rays. The alignment looks very, very straight, the components are accurately sized for that particular patient and usually we have an excellent range of movement at the end of the operation in theatre and then we would expect this patient to do very well with their exercises and get back doing their normal activities and their normal function.

So, what are the benefits?

Obviously, the benefit of this operation is to get the knee replacement accurate for the individual patient, get the knee replacement sized accurately which helps with reducing the operative time often by ten or so minutes and there's less interoperative trauma due to less instrumentation of the bones during the operation. This often helps with early recovery and gets people out of bed moving quicker, less pain, less swelling.

Times have changed with knee replacements when I was a junior doctor. People often stayed in for a week or two. For the first day or so you rested in bed. This has now all changed so, if I operate on your knee in the morning I'd expect in the afternoon you to be sitting in a chair, to have perhaps stood with the frame with the help of the nurses on the ward and the physios, perhaps walked a few steps tentatively to the loo.

What I'm really trying to say is, after a knee replacement it's not resting in bed and spending days to recover, it's getting out of bed, getting walking, get the knee bending and straightening and get back to normal activity as quickly as possible. So commonly we like people to get up the same day. A common length of stay is two nights in hospital, but patients obviously only go home once they're safe and the nurses and the physios have assessed them and assessed they're safe to go home.

So, the indications for a knee replacement we've talked about, but the special indications for this Signature are often patients with previous deformities. The x-ray here shows previous fractures, and clearly here getting the alignment with standard techniques will be difficult so Signature can be very beneficial with the planning, with the MRI scans, younger patients to get the alignment accurate and patients with a higher demand of their knee replacement. Not everyone has a correct indication for Signature and indeed I do more standard knee replacements in the year than Signature knee replacements.

The actual implant that's used is the same one; it isn't better than the other, but the idea of this Signature is just to get the alignment better for these more complex patients.

So that's my whistle stop tour of knee replacement surgery. I'm sure there are a number of questions and I'd be delighted to answer your questions as you put them to me. Thank you.

Zoe Andrews

Thank you, Mr Goddard. So, we've had a question through and the first question is: How long does the operation take?

Mr Goddard

That's a very good and common question. The actual surgery time takes about an hour to an hour and a half, dependant on the complexity of the operation, obviously the severity of the arthritis, and the patient's body habitus, whether they have a big knee or a nice thin knee. Often about an hour and a quarter is a usual time, but one has to remember that there's an anaesthetic time prior to this which often takes around half an hour.

Commonly for a knee replacement the Anaesthetist, if appropriate, will do a spinal anaesthetic which involves passing a small needle under anaesthetic into the the back and this numbs the nerves from below the waist down. So, with this anaesthetic technique you feel no pain and you have prolonged pain relief after the operation's finished.

So, the whole time in theatre with anaesthetic and recovery is probably in the region of around two hours.

Zoe Andrews

Thank you. So, we have another question here from Sue, and Sue asks: My arthritic knee has become much more painful this year, and I've increased my co-codamol medication. Could you advise me at what stage I may need to consider surgery?

Mr Goddard

So again, everyone is different; everyone's pain tolerance is different. I usually say to patients that you should have tried sort of simple analgesia, the activity modification. Some people may or may not try an injection. They don't last forever; if an injection works well it may last three to six months but it's not going to cure the arthritis in the long term.

Commonly, I'd want a patient to have severe pain every day, often pain at rest, pain at night and pain limiting their activity such that they struggle to walk for ten, fifteen minutes round the shops without having to sit down and rest

If you replace the knee too soon, when patients only have mild or insignificant pain, then the result of the operation is often not as good as when you replace the knee with someone with severe pain, so timing of the surgery is critical. So this is based on the severity of the arthritis on the x-ray, so you come to the hospital and we can get up-to-date x-rays and also when the simple things that normally help your pain (the painkillers) don't work anymore then that's the time to think about a knee replacement if your symptoms are severe.

Zoe Andrews

Thank you, and the next question is: I try to keep as active as possible and I do go for a walk every day on the flat, as the incline causes me more pain and I just wanted to check that this helps and will not cause any more damage to my joint

Mr Goddard

So, pain on incline is often indicating there's significant arthritis of the patellar femoral joint (the kneecap joint). Patients here often have pain at the front of the knee, pain is worse going up and down stairs hills and slopes and pain getting out of low chairs, getting off the loo that type of thing. With a severely arthritic knee, if you remember the x-ray where the cartilage is lost and the bones are touching together, then in the short term no more damage will be done. In fact, it's better to exercise and use the muscles around the knee to keep them strong.

If one just sat and nursed a sore knee, not exercising the muscles, that - in the long term - could make the arthritis worse and the knee more unstable, so doing gentle walking, gentle exercises within reason will help keep the muscles strong and is not, in the long term, doing any more significant damage.

Warning signs would be, however, if you get more instability, mechanical problems like the knee tending to give way without warning and if you feel, or your partner or friends see, that the knee joint is becoming more deformed then this is really saying “Seek medical advice and get new x-rays” because you could be eroding the bone, and this is then where problems could arise with needing more complicated surgery.

But the vast majority of patients don't run into those problems.

Zoe Andrews

The next question is from Ian, and Ian is asking: What is the success rate of the procedure and what reduces this success?

Mr Goddard

This is a very interesting question and depends how you measure success. So, there's a number of markers for success, surgically. We base success on how long the knee replacements lasts, so we have a joint register which is attached to your NHS number - not your data, not your name or your address. So, if you move around the country, the joint register will sort of follow you and find you. And a knee replacement, commonly in someone age nearly 70 say, will last around 15 years and this is a successful result.

What alters success is patient's activity, so people who do more demanding things with a knee replacement. Certainly, people who run, and people who do higher level sports. Certainly contact sports, squash, long distance running and things like skiing put more and more wear on the knee replacement then this would cause early wear of the artificial joint, wear of the plastic and then could cause the knee replacement to wear out and fail sooner than we would like.

Other factors are weight. If you're overweight, that could put more force and stress through the knee replacement. An analogy to use would be if you think of buying a new car. If you think if you drive that car more, use it for example like a taxi, always driving to the airport every day and that would wear out sooner than if it was your pride and joy car that you just used on a sunny afternoon every Sunday. Clearly that car would last longer.

The idea of a knee replacement is to get you doing your daily activities, get you walking, so you shouldn't sort of protect the knee but the more activity you do, the less likely it is to last in the long term. Other factors are the severity of the arthritis, the deformity of the knee, how well the knee replacement is done with respect to alignment and these are all in the surgeon's control, not the patient. That's what is success for a surgeon.

Now clearly, for a patient the success is different. A patient would want - after say three to six months – to be pain-free, a knee that works nicely and a knee that helps them to do all of their activities. Now some of that is in the surgeon's control with how well the operation is done, how nice the alignment is, and some of that is directly under the patient's control on how well they've done their exercises, have they got their knee moving, then all the muscle strengthening and are all the things required of them. So it's a bit of a two-way process with respect to early success.

So, if I had someone who didn't do their exercises, then the success of the knee replacement would be significantly lower. Generally speaking, major complications of a knee replacement are fortunately very rare but do on occasion happen, and if you're unlucky to have a significant complication - such as nerve damage, arterial damage or a fracture - these are all very, very rare but will happen somewhere. You know, at one hospital every month in the south of England one of these complications will happen and to that individual the outcome will be quite poor. So, we all have to think carefully before undertaking major surgical intervention of an arthritic knee.

Zoe Andrews

Thank you. The next question along similar lines around the recovery period so: Approximately how long would you say that that recovery period was after a knee replacement?

Mr Goddard

Again, that's a very good question. It's dependent on many things; very patient-specific as well. As a general rule, for the first two to three days the knee is very sore. Often people have significant pain while they're in hospital, but it's controlled with the medication that they're given. For the first two weeks, while the metal clips and staples are still in the skin from wound closure, the knee is often bashed and bruised, sore. But you must do the exercises. You'll still need significant pain killers.

By six weeks most people have turned the corner; the pain is better but still present. They're on more simple or less strong painkillers. At six weeks I’d be expecting someone to be able to walk around their home, most people are driving a car a short distance. You should be able to walk short distances outside, you know to the local paper shop, that type of thing - but you must be doing your exercises.

At six weeks, a lot of people are still unsure whether the knee replacements help their severe pain or not. However, by three months most people come back to clinic, glad they've had the operation done. But if truth be told all the little niggles of a knee replacement do take another six months to fully settle down, and around nine to nine months to a year is the amount of time before people commonly forget that they've had a knee replacement.

So, it does take a long time to fully recover but, before you were ready to, say, go on holiday and enjoy, you know, two weeks in Spain that's usually around three months after the operation.

Zoe Andrews

Alan's asking around stem cell therapy and his question is: is stem cell therapy under the kneecap to replace the cartilage feasible?

Mr Goddard

On my slide of cartilage transplantation, this is all encompassing stem cell treatment, so it's fair to say this is new treatment not routinely available and commonly is done in specialist centres who are doing research into stem cell treatment.

Stem cell treatment is, at the moment, ideally suited to treat individual cartilage defects so if I use an analogy like a road; if you have a completely worn out road, the council come along and resurface the entire road and with the knee joint with global arthritis that's a knee replacement. If you had a nice smooth road, but there was one pothole in it, the council would come along and fill in the pothole and that, in the knee, is where stem cell treatment and cartilage transplant could be considered.

So, if you're unfortunate enough to have an injury and you've lost a bit of cartilage in a discrete area, like having a pothole in the knee, then stem cell treatment could be considered to try and plug and grow cartilage filling that pothole

The problem here is that the patellofemoral joint (the kneecap joint) takes a lot of force and growing cartilage on the kneecap is probably the hardest place to do so as the forces going through the kneecap with daily activities are very high. So, success rate of cartilage transplants stem cell treatment on the kneecap joint at the moment is very questionable. It can be successful but it's not routine practice at the moment.

Zoe Andrews

Thank you. The next question is from John and John is asking: if you suffer from arthritis in both your knees, would you operate on both at the same time?

Mr Goddard

Personally, I choose not to operate on both knees at the same time. One knee replacement is a major operation; it's a significant anaesthetic, there's significant stress to the body. Often people having a knee replacement are in their late 60s early 70s, sometimes older, and it's not unusual for patients to have other underlying medical problems

So, for patients with severe arthritis of both knees, it's usually more sensible to do staged operations - either the worst one first that the patient feels is the worst knee, or the one that's worst on the x-ray. And then once you've had a good recovery, patients come back at six weeks saying “Look I'm really pleased” with it then we can get the ball rolling and then three months later do the other knee.

But if people are still struggling, then we wait till they're happy with the first knee replacement and then go ahead and replace the other knee once they're happy the first one's done well. Doing both together is not routine practice, commonly, and can lead to medical problems of the anaesthetic, breathing problems, heart problems, blood clots and generally it's a higher risk undertaking. So, it's safer to do one knee first and then the other one three to six months later

Zoe Andrews

And the next question is from Linda and Linda's had a knee replacement and she would like to know whether she can use the vibration plate that you get in a gym?

Mr Goddard

I've been asked this a number of times and personally I feel that, if you don't have any pain from the knee replacement, then the vibration plate is probably - once the knee replacement has fully settled down - absolutely fine.

The vast majority of knee replacements are fixed to the bone with cement. Some are uncemented, which rely on the body to grow bone into the knee replacement but, essentially after around nine months to a year, the knee replacement strongly fixed to the bone if it's uncemented. With a cemented one, by the time the operation is finished it's as strong as it's going to be and simply is unlikely to cause any problems

Obviously if you do have pain, because you can be aggravating some of the muscles around the knees, some people have pain using the vibration plate, then if that's the case it's better avoided. The best exercises to do at the gym following a knee replacement, to build up the thigh muscles, the quadriceps and the hamstrings, which then help keep the knee replacement stable in the long term

Zoe Andrews

Thank you. If a patient has arthritis in the hip and the knee joint of the same leg, would it be necessary to operate on one joint at a time or could both joints be replaced at the same time?

Mr Goddard

This is very similar to the question on having both knees done, except that it's usually usual - if both knee if both the hip and the knee are severely arthritic - commonly we would recommend to have the hip joint replaced first, followed by the knee. If, however the knee joint is more arthritic, and causing more pain, then you can have the knee replaced first and then followed by the hip. But it's very, very unwise and I would say I know a very few surgeons who would contemplate doing a hip hand knee replacement at the same time.

So, the answer is usually do the worst joint first, followed by the hip or the knee afterwards.

Zoe Andrews

Now the next question is from John and he's asking if he comes for a consultation, and it's considered necessary to have an x-ray or an MRI scan, can this both be done at the same time?

Mr Goddard

At most hospitals you would get an x-ray the same day, so we usually get weight-bearing x-rays - looking at the knee from three angles. Prior to the COVID pandemic it wasn't unusual for someone to be able to get an MRI if it was pre-planned on the same day. But now, with COVID, sadly the MRI scan has got a bit of a backlog. So, at the moment MRI is not usually possible on the same day.

However, I would have thought in the future, with planning, it's possible to pre-book these tests and, if you live a distance away, to perhaps come in the morning have the MRI and the x-ray and then see me in the afternoon

Zoe Andrews

Thank you. And our last question is: is mobile bearing knee replacement an option?

Mr Goddard

Patients often (and rightly so) look on the internet, and you could search knee replacements and there's many many different types.

There's fixed bearing, mobile bearing, and what this means is how the plastic cartilage is moving in the knee. So commonly, a fixed bearing knee replacement is more common, and this is where the plastic artificial cartilage is fixed to the tibial base plate. It's either prefixed in the factory or, more commonly, it's fixed at the end of the operation with a locking pin

Mobile bearing was invented to try and reduce wear of the plastic, and some studies show that this has been the case and other studies show with mobile bearing there's wear on both sides the bottom of the plastic and the top.

So even though mobile bearing knee replacements can be considered, the studies probably show that there's no significant difference between the two. And it's really then down to surgeon preference. And it's better to have the knee replacement that the surgeon is happy and confident doing rather than try and persuade a surgeon to use a different type of knee replacement that has theoretical advantages over other ones

The one we use here at Benenden is the Vanguard knee replacement. This is in the top three commonly most used knee replacements in the country and it has good long-term results, good functionality. Most Vanguard knee replacements are fixed bearing in nature, but some surgeons would opt to use a mobile bearing knee replacement. One isn't better than the other, it's really surgical preference and what that individual doctor believes in, the philosophy they've been taught.

Zoe Andrews

Thank you, Mr Goddard, and thank you all for contributing with your questions. You'll receive a short survey by email and I'd be really grateful if you could spare a few minutes to let me have your feedback on today's webinar

If you've got any further questions from the presentation or if you'd like to book an appointment to see Mr Goddard, please call our Private Patient Team here at Benenden Hospital by the number on the screen. The calls will be answered during office hours, or you can leave your details and we will return your call.

Our next webinar is on Thursday the 12th of November at 2 p.m and the topic for this session will be endoscopy with Dr Lawrence Maiden, one of our Consultant Gastroenterologists

So, on behalf of Mr Goddard, myself and all the team here at Benenden Hospital, I'd like to say thank you very much for joining us today and we look forward to you joining us again for another webinar very soon. Thank you for joining and stay safe.

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