Comorbidities, obesity, diabetes and age why they matter for hip and knee joints Dr Bernard Zicat

This podcast centers on the complex interplay between obesity and diabetes as comorbidities in the field of orthopedics, specifically focusing on their impact on surgical outcomes in hip and knee arthroplasty. Dr Bernard Zicat, with extensive experience in implant design since 1994, reflects on the evolving perceptions of these conditions in the surgical realm.

The discussion begins with an overview of diabetes, acknowledged as a significant concern due to its historical links to wound healing and infection risks in surgical patients. It is noted that while the incidence of diabetes has shifted over the years—especially with advancements in management of insulin-dependent patients—its correlation with surgical complications appears less pronounced today compared to the cardiovascular risks associated with surgery. Citing a German study, Dr Zicat points out that diabetic patients often present higher body mass indexes (BMIs) but that their overall surgical outcomes, including pain management, do not differ significantly when BMI is adjusted.

The bulk of the lecture focuses on obesity, drawing on robust data from the National Joint Replacement Registry to illustrate the high incidence of joint replacements among obese patients. It is emphasized that those in higher obesity categories show a disproportionate need for knee and hip replacements, with factors such as joint instability and increased translational forces contributing to the wear and tear of these joints. There is a notable rise in younger patients requiring such procedures, predominantly linked to obesity, raising concerns about the long-term implications on joint health.

Dr Zicat discusses the surgical challenges presented by obese patients, including prolonged operative times and complications related to wound healing, particularly in hip replacements where surgical incisions are affected by surrounding fat deposits. Historical context is provided on past recommendations, which discouraged surgery in overweight patients, highlighting the difficulty in encouraging weight loss among individuals with joint pain who struggle to exercise.

The management of weight loss is explored, including surgical options and the emergence of pharmacological treatments like semiglutides, which have shown promising results in significantly reducing weight. However, the speaker clearly states that weight loss alone does not necessarily prevent the development of osteoarthritis nor eliminate the need for joint replacement once osteoarthritis has already progressed. Instead, it may temporarily alleviate symptoms and postpone surgery, but eventually, many patients still require intervention.

Obstructive sleep apnea emerges as a common concern among obese surgical patients, yet the evolving management practices in post-operative care reflect a growing comfort in treating these patients without extensive ICU stays. The focus shifts to the increased risks associated with surgery in this demographic, particularly regarding infection rates, emphasizing the importance of advanced wound management techniques which have revolutionized care, such as negative pressure wound dressings.

The lecture concludes with a summary advocating for a reconsideration of strict BMI policies that govern surgical eligibility. The evidence presented indicates that obese patients experience comparable satisfaction and functional improvement post-surgery relative to their non-obese counterparts, despite a higher risk of complications. Hence, the speaker recommends that patients be informed and encouraged to pursue surgery when necessary, as the benefits significantly enhance their quality of life. Overall, this discourse sheds light on the necessity of a balanced approach to managing obesity in orthopedic surgery, reinforcing the idea that with proper care and techniques, surgical outcomes can remain satisfactory across diverse patient populations.

-------------------------------------------------------------------------------

Access thousands of additional conference podcasts and 'full video' podcasts including synchronised PowerPoint slides at https://www.armchairmedical.tv/podcasts

Disclaimer: Content is for health professionals and general educational purposes only. It is not medical advice or a substitute for independent clinical judgement. Always consult current guidelines, product information and local protocols. Views expressed are those of the presenters and not necessarily ArmchairMedical. ArmchairMedical accepts no responsibility or liability for any loss or harm resulting from reliance on the information provided.

Visit https://www.armchairmedical.tv/podcasts for more information.

I have been asked to talk about two specific comorbidities.

I won't spend much time talking about diabetes, but talk a bit about obesity.

Some of that's been talked about already.

These are sort of topics that we're going to touch on.

I have been involved in implant design since I started in orthopedics in 1994. four.

So these two comorbidities in orthopedics have been much discussed.

I was looking up the data on the incidence of obesity and diabetes,

and I always thought that they were very closely linked.

But it does look like the rates of obesity in the Australian population peaked,

many years ago and are decreasing, whereas the levels of obesity are going up.

And I'm not sure why that's true, whether it's an education or treatment algorithm,

but the obesity rates certainly are continuing to increase.

This is the only thing I will say about diabetes.

When I started in orthopedics,

we flagged diabetics as being potentially at significant risk of primarily wound

healing problems and infection,

and because of the effect that it had on their general immune metabolism,

if you like, or physiology. Yeah.

And I think that in those days, the incidence of insulin-dependent diabetes

was much higher than non-insulin-dependent diabetes.

And as the treatment of insulin-dependent diabetes is improved,

and it tends to be a different profile of diabetics, we just don't see any particular

complications in those patients.

So I've spoken to my anesthetist about it.

He patients come in that have

poor glycemic control it doesn't affect

his management of the patient and I've

never seen Nargis who looks after all our patients very well say this patient

is diabetic out of control it can't have the surgery done they do manage it

they treat it but it doesn't have the same effect on their risk of surgery say

than cardiovascular issues.

There's a study that was done in Germany that looked at specifically the incidence

of diabetes and also the incidence of poor glycemic control measured by hemoglobin A1c.

And they found that diabetics were more likely to have a higher BMI and other

comorbidities, which is to be expected.

There was a slightly longer length of stay in diabetic patients.

But when adjusted for body mass index, it was no greater.

And they had more difficulty with pain control.

But again, after adjusting for BMI, there was no difference.

Otherwise, the clinical results were similar, regardless of their diabetic status.

And there was no other evidence of difference in outcomes longer term.

So for us, diabetic patients obviously need to be well managed,

but it doesn't affect our treatment of the patients when they come in for surgery.

Obesity is a different matter. A lot of the data that I will show you is data

from the National Joint Replacement Registry.

And this is the problem with obesity and osteoarthritis.

So if we look at the incidence of joint replacement or the occurrence of joint

replacement patients in various classes of obesity,

and these are obviously over a very large number of cases that have been collected

on the joint replacement registry, we can see that for hip replacements.

There's an increased incidence of joint replacements in more obese patients

compared to what you'd expect, the normal sort of curve around normal weight.

And there's even more of an effect if we look at knee replacement patients where

there is a predominance of patients that are in the overweight or obese categories.

So what this tells us is that if you are overweight, you're at increased risk

of getting hip arthritis and even at more increased risk of getting knee arthritis.

And I think the reason for this predominantly is because the knee joint doesn't

have the stability that the hip joint does, the forces in the knee,

which include translational forces under the effect of obesity,

are more likely to cause chondral damage and lead to arthrosis.

And we can see the number of joint replacements that we've been doing have been

going up basically every year in all of the categories,

and certainly a large representation for younger patients.

So, this is a study that, I can't remember where it was done,

but indicative of the issue, looking at the incidence of osteoarthritis in younger patients.

And younger patients will have a variety of causes of their arthritis,

which may be post-traumatic or it may be idiopathic in patients who have been

particularly more active.

But they looked at the patients who had hip or knee replacements done within

their group over a period of time in the early part of the century,

and they found that obesity was associated with the need for knee replacement

or hip replacement compared to other adults of similar age in the general population.

So again, they're overrepresented.

72% of the study group was obese, and there were only 26% in the general population.

And that matches with the demographic numbers that I've shown before.

Knee replacement patients were significantly more likely to be obese than hip

replacement patients. So it's a problem with knees, more so than with hips.

So what does that mean for surgery in these patients?

Well, So, certainly, obese patients are harder to do.

The operative times are increased. They do have wound healing problems,

and that's a result predominantly of the development of fat necrosis,

leading to wound healing complications.

It's particularly bad for hip replacement patients. Most fat patients.

Pattern deposition is concentrated around the hips rather than the anterior

aspect of the knees, the lateral aspect of the hips.

And that's where we're doing our surgical incision.

So the number of fat cells, as you know, is not different in obese patients.

The tissue is just essentially very thin layers of fat cell membrane with large globules of fat.

And trying to close those spaces with sutures is difficult.

The tissue, the fat tissue, the cells that are damaged often break down.

You get fat necrosis. You get drainage through the wound, superficial infections,

and then the infections propagate and become deep.

And about 15 or 20 years ago, there was a huge initiative in the orthopedic

community to refuse to operate on patients who were overweight or obese.

We were all taught to tell patients to lose weight or they wouldn't be a candidate for surgery.

And discussions with patients who have weight problems, as I'm sure you all

know, is not that easy and the effectiveness of the conversation is not that great.

Patients come in, they say, well, I can't exercise to lose weight because my

joints hurt and then when you tell them, statistically speaking,

they're more likely to gain weight after their knee replacement or their hip

replacement and sometimes they get a little bit angry.

And there was this period of time many years ago that,

And there was a surgeon from Tasmania in Australia who was particularly vociferous.

He would be paid by or invited by orthopedic companies to go to meetings and

tell everyone that we shouldn't be operating on any patients who are overweight or obese.

We should take them off the waiting list, tell them to come back when they'd lost weight.

And it was probably the result of personal experiences that they'd had with

complications in overweight patients.

I thought there was a bit of a fat-shaming exercise at the time,

but it was commonly discussed.

And the NHS in England also started introducing limits on weights that patients

could have before they could have a joint replacement done. and requiring them to lose weight.

And getting them to lose weight is not that easy.

As I'm sure you all know, we talk about diet, obviously, which is I'm sure a major part of it.

Doing exercise, which joint replacement patients.

Arthritic patients find difficult to do. Most of the...

Thank you. I've never had much success in getting patients to lose weight,

but I don't spend as much time with them in a longitudinal fashion than GPs do.

But patients who have effectively lost a lot of weight, patients who lose in

the 20, 30, 40 kilos, historically, it's been basically bariatric surgery.

Has been the most common.

And now, obviously, the semiglutides, and I've started to see patients now who

have lost 40 kilos using Ozempic or Wagova.

So that's also very effective.

And what happens if they lose weight before their joint replacement surgery?

Well, if they lose weight when they're 20 or 30, the evidence is there that

they probably won't develop osteoarthritis, so they'd be less likely to develop osteoarthritis.

Once they already have the osteoarthritis, losing weight doesn't really improve the arthritic signs.

It can improve the arthritic symptoms. If they lose weight, they can have decreased

pain, and they may go for some time before having to have knee replacement surgery.

But patients who I've seen who have had massive weight loss in the past have

ended up having their knee replacements or their hip replacements not long after.

So I'm not sure that it's that effective as a long-term measure once the arthritis has kicked in.

As far as the perioperative management, obstructive sleep apnea is probably

the most common, difficult problem that we deal with.

And that's not something that I have to deal with particularly,

but definitely we're becoming more comfortable with sleep apnea.

It used to be, even just a few years ago, that anyone who had significant sleep

apnea went to the intensive care unit postoperatively, and that's not happening anymore.

So people are being more comfortable managing sometimes with their own devices on the ward.

Drug control can be complicated because of the distribution patterns,

and doing blocks are more difficult because of the depth of penetration that's needed.

Some of these patients do have cardiac risks, and there's no doubt that they

have increased cardiac strain.

But as long as those are managed, which Nargis does for us very effectively.

From that point of view, it's not a restrictive aspect of their morbidity.

The surgery is definitely technically more demanding.

And at the time that this all came up, people were saying, oh,

we should get paid more for it, that sort of thing.

So, then if we looked at the evidence that this whole movement was based on,

you know, lose weight or don't have a hip replacement, well,

or knee replacement, if we look at how implants fail, basically the most common

are loosening, wear, and infection.

Infection is the one that has been particularly highlighted in patients who are overweight.

And there have been studies from the states particularly, and there's no doubt

that if you get someone who's got a wound infection, becomes a deep infection,

and they're extremely overweight, it's a difficult problem to manage.

I mean, the surgery's big, there's a lot of tissue involved that needs deprivement.

It's not a fun sort of procedure.

We looked at, at the time that this all came out, I wasn't that impressed that

patients with a high BMI didn't do well.

So we looked at our series of patients. We had a big database at the time with Bill Walter.

And we looked at our comparison between our obese and non-obese patients and

looked at their functional levels. And this we've published in the Journal of Bone and Joint.

And what we found was that there was no difference in survival rate when we

looked at the obese patients compared to our controls at over 10 years follow-up.

The obese group had lower pre-operative and post-operative hip and knee scores

and a lot of this was based on a decreased range of motion so when you've got

very large thighs and calves you can't bend your knee that well you don't move your hip that well.

But their satisfaction scores and functional scores were comparable.

And I can tell you that patients who carry a lot of weight on an arthritic joint,

that generates a lot of pain.

They hurt. And when it's replaced, they are very appreciative.

Um, there was no difference in

the radiographic analysis. There were no increase in the loosening rates.

Um, and we were also at the time using, uh, not the modern crosslink polyethylenes

that have very low wear rates.

We were using, uh, standard ultra high molecular weight polyethylene and that

polyethylene did wear and it was measurable wear.

And we had a computer program that measured head penetration on hip replacements.

And we expected to find that obese patients had a higher wear rate than non-obese patients.

What we found was that the relationship was inverse.

Obese patients don't take many steps. And thin patients who are very active take a lot of steps.

They get more abrasion of the joint surface. and that led to higher penetration

rates and higher rate of wear of polyethylene.

There was no difference in the midterm survival. This study was done after 10

years with the presence of obesity.

So we felt it was unreasonable and that was the comment in our study to withhold

arthroplasty surgery on that basis.

Other studies have shown the same. Here's a study.

Another German study that looked at the results of joint replacement surgery in heavy patients.

And what they found was that the hospital, sorry, the hair sip scores and hospital

special surgery scores were significantly lower at the time of treatment in the obese population.

There are complications were similar in form and quantity to the normal population

and the joint replacement patients with a higher BMI were treated at a younger age.

They also found that there was no particular increased risk.

Some techniques were used to be able to accommodate heavy patients,

but the results were all satisfactory.

Another patient, this one was done at my old orthopedic training center in London, Ontario.

They looked at the same sorts of issues in obese patients. they found that the

pre- and postoperative scores were lower for the morbidly obese.

Their outcome scores were equal or greater than the non-morbidly obese,

the improvement in the scores.

Survivorship and rate of complications were similar.

A slightly higher rate of revision for sepsis in the morbidly obese group,

but it didn't affect the outcome otherwise. and they also felt that withholding

surgery on the basis of their BMI was not appropriate.

We look at the results from the joint replacement registry, very large numbers of patients again,

and these are the preoperative and postoperative visual analog scale for quality of life, for hips,

and the Harris, sorry, the Oxford scores for hips, same thing for knees on the bottom.

You can see that the more obese the patients are, the lower their scores are preoperatively,

but they do make significant improvement postoperatively in all their scores,

and they get very close to the functional levels and quality of life levels that the non-obese do,

and they also have a more significant improvement compared to the non-obese,

and I think that relates primarily to the poor functional level of the obese

patient who has an arthritic joint.

Um, the NHS went back and did a formal review of the impact of policies that

they had for BMI access to elective surgery.

And they did this in about 2018.

Not all of the NHS services, there's a word for their,

I don't think there are areas, but the different sort of National Health Service

administrative areas introduced these policies.

And when they looked at the results, they're again looking at a large number of patients.

When they looked at the localities, which introduced these policies,

They found that they had higher surgery rates before they introduced the policies to those which didn't,

and their rates of surgery fell after their policy introduction,

whereas the rates in localities with no policies rose.

So basically, the obese were going to a different area to get operated on.

The strict policies mandating BMI threshold were associated with the sharpest

fallen rates. So they definitely stopped operating on them.

And some of those localities had higher proportions of privately funded surgery.

So if they had money, they went and had the operation done anyway.

And their findings of this study was that it was increasing health inequalities,

that policies that enforced extra waiting time before surgery resulted in worse

pre-op scores before surgery and rising obesity.

And their conclusion was that the effects of BMI policies on patient outcomes

and inequalities were counterproductive, and they recommended that the policies

involving extra waiting time or thresholds be abandoned.

Now, what is the risk? Well, here's the infection risk with hips.

And as I said, hips are more of a problem than knees because of the thickness of the fat layer.

And there's no doubt that there is a higher rate of infection in very large

patients who have hip replacement surgery.

The effect in knee replacement is not quite so large.

So the rates are very similar to those in lower levels. And I think that's because

primarily it's not an issue of the amount of fat on the front of the knee.

Now, how do we deal with this? Well, basically, the improvements that we've

had has been around wound management.

And this has been the number one sort of technique that we've been using,

and that is negative pressure wound dressings and Pravena vac dressings, Pico dressings.

It decreases the fluid within the fat layer. It expresses it to the surface.

It prevents introduction of bacteria. And it has been an absolute game changer.

And we found that it works through a macro deformation and micro deformation

model of the wound blade, removes the fluid, stabilizes the environment and

improves wound deposition.

In addition to this, we've also been starting to use these just examples of

how this and it really is. We've started using this for trauma wounds.

We've used it for elective wounds. And it's been a real game changer.

We're also using dressings that now seal the wound, a glue with a mesh over

top of it, and that also has been very effective.

And it has reduced the difficulties that we've seen with infections around large

wounds, and we've been able to use it very effectively.

So in summary, diabetic patients have no increased risk with hip and knee arthroplasty

surgery regardless of the level of glycemic control.

Obese patients are at higher risk of developing hip and knee arthritis.

That they should be encouraged to lose weight.

And there are a number of techniques now that are becoming easier for them to

do that. If it exists, the weight loss may help to improve pain.

It may delay the need for arthroplasty, but that's usually inevitable.

And they should be offered surgery because it has a significant effect on their

quality of life and their results are essentially similar to those without obesity. Okay?

Thank you. Thank you.