Infected fractures

In this Biocomposites Education series, Dr Tracy Watson answers some of the common questions surrounding the causes, impact and treatment of infected fractures. You can also watch him answer some of the questions in our video series.

Videos
1Who is Dr. Tracy Watson?
1
Who is Dr. Tracy Watson?
2
What is an infected fracture?
3
What is an infected non-union?
4
What causes an infection?
5
What are the symptoms of infected fractures?
6
What is the difference between an acute infection and a chronic infection?
7
What are the treatment options for infected fractures?
8
What role do antibiotics play?
9
What are the complications associated with infected fractures?
10
What can patients do to help heal infected fractures?
11
How important is it to know the particular pathogen that’s causing the infection?
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Does the risk of infection differ between open and closed fractures?
13
How do you grade fractures?
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How quickly will an infected fracture heal?
15
How can reoccurrence of infection be prevented?
J. Tracy Watson, MD

Professor of Orthopaedic Surgery

‘Infections in open fractures are commonly caused by contamination from outside the body that gets implanted or injected into the wound. A non-union or infected non-union is usually the result of previous intervention such as surgery or an open fracture.’

Q & A
Who is Dr. Tracy Watson?

I’m Tracy Watson, I’m a Professor of Orthopaedic Surgery at the University of Arizona, College of Medicine in Phoenix and I work with the CORE Institute in Phoenix. My specialty is Orthopaedic Traumatology and I take care of a lot of traumatic injuries, fractures and open fractures. I have a sub-specialty in the area of bone infection, non-unions, limb length discrepancy and limb deformity as well.

What is an infected fracture?

Infected fracture is a broad definition, but essentially an infected fracture is usually an open injury, or sometimes a closed injury, that has undergone surgery. The wound becomes contaminated, and becomes red, swollen, hot, with some drainage, and is colonized with some type of bacteria. Usually it occurs 7 to 10 days after surgery, once the wound is closed and it starts to drain.

An open fracture or a compound fracture can be contaminated or infected right from the get-go, because it is contaminated from outside the body with road debris, gravel or what have you. An infected fracture is usually an acute type of an insult that occurs shortly after surgery or shortly after the injury that has occurred.

What is an infected non-union?

An infected non-union is long standing, in other words, the bone has had a previous fracture, the bone has not healed, maybe one of the reasons it didn’t heal is because there’s a low grade infection, a low grade colonization into the bone or around the wound that’s preventing that bone from healing.

It’s different from an infected fracture, which occurs acutely. An infected non-union smolders along, may not be manifest, but you may just note that the fracture hasn’t healed and then once you start to treat it you discover that not only has it not healed, but it’s also infected.

What causes an infection?

In the case of an open fracture it may be from contamination outside the body that gets implanted or injected into the wound. That’s the most common cause of an open fracture that becomes infected. A non-union or infected non-union is more chronic and that’s almost always as a result of previous intervention, whether it was surgery or an open fracture. It gets colonized at the time of surgery, sometimes by local skin bacteria or by the surgery itself where there’s a contaminant in the operating room and it lodges in the wound and then just smolders along. There are many potential etiologies. A lot has to do with the condition of the soft tissue. An infected fracture can happen just because you have very traumatized soft tissues and the body therefore doesn’t have its normal defenses to fight off a low-grade contamination. It can happen just from a routine injury where its contaminated or it can happen as a result of poor soft tissues that are not able to provide the body normal defenses.

What are the symptoms of infected fractures?

Most of the time it’s obvious. You have redness, swelling, pain, and drainage. Although those are the most overt signs, occasionally it can be very subtle, and you may not even know it occurs. Most commonly with an infected non-union, all you really know is it’s painful and the bone hasn’t healed. And you don’t know until you provide surgical intervention that it’s contaminated and there’s an infection – which is probably the reason it didn’t heal, or one of the reasons it didn’t heal. So, you may not know at all that you have a chronic infection, just that the bone didn’t heal.

What is the difference between an acute and a chronic infection?

An acute infection is going to happen soon after the injury or the surgery. Let’s say you break your leg, you have a rod put in your leg, and within two weeks the incision starts to drain a little bit. That’s usually what we would call an acute infection. It’s a lot different than an infection that doesn’t really manifest itself for 9, 10 months or even a couple of years. Again, it’s a question of timing. An acute infection is often easier to get rid of because you catch it early on, it hasn’t had a chance to establish itself. The soft tissues may be part of the issue, but the bone really hasn’t been thoroughly colonized where you must remove infected, dead bone. Whereas an infected non-union, the infection has been there longstanding, it’s into the bone usually, and you have to then get rid of that bone in order to cure the infection. It’s a question of chronicity, how long has it been going on prior to you noticing it or it becomes clinically manifest.

What are the treatment options for infected fractures?

An infected fracture, most of the time, is a result of surgical intervention. If you have done a repair to fix the fracture, the first thing you must think about is, when was the initial surgery and when did the infection present? If it’s acute, meaning within the first 3 to 4 weeks, that’s a good sign because there’s a good chance you can eradicate that. The second thing you look at is; how stable is the fixation? Is that plate providing very rigid fixation?, because if it is, then oftentimes you can leave the plate, clean out the infection – and even though the plate is probably colonized – the body defenses are still able to fight it off long enough until the fracture heals. We do know even in the case of a contaminated fracture, that if you have very stable fixation, the bone will go ahead and heal despite a low-grade contamination.

Assessing the degree of stability of the fracture is very, very important. If, for instance the plate is loose, or the rod is not providing any stability, it’s fighting against you. That instability prevents the body’s normal defenses from helping you. So that plate and the instability must be removed. Most of the time in an acute fracture, where the fracture fixation is rigid, you can treat it and leave the fixation in place. The bone will go ahead and heal. You may later have drainage coming from the colonized hardware, but then you can take that out and everything is fine. That’s opposed to a situation long term where let’s say you had a plate in. The plate is broken. It’s two years down the road, and you’ve had drainage off and on. At this point because there’s no stable implant, that hardware is hindering you and acting as another nidus for infection. Not only do you have to take the hardware out that’s not providing any stability, you also must take that dead bone, the infected bone, out as well, to essentially establish a healthy biologic envelope – and then start the whole process over. Re-bone graft it, re-plate it, etc. etc. But the first thing you must do is put the biology back to a healthy, stable wound before you can proceed.

What role do antibiotics play?

Antibiotics require a pipeline. And a lot of times, in chronic infections, you have dense scar tissue that’s been there for a long time and you have dead bone. There is really no pipeline to deliver the antibiotic to the site. And so, in order to get the antibiotics going, you must take away the dead infected tissue, the dead infected bone back to healthy bleeding bone, so that you can deliver antibiotics.

Some people would argue that maybe you don’t even need antibiotics because it’s a surgical disease. Where you have bad scar tissue that’s not viable, you should take that out, get healthy biology back and then everything should heal. But I think most people would argue that peripheral antibiotics, adjuvant antibiotics, are very helpful to take care of the areas that are marginally viable that may survive if you give them antibiotics or die if you don’t. I think antibiotics are part of the treatment of an infected non-union.

In the case of an infected fracture, I think they’re vital because if the tissues are still in reasonable condition, they are going to deliver the antibiotic. They haven’t had a chance to scar over and be atrophic and not biologically active. That gets into a host of local antibiotic adjuvants where you deliver antibiotics right to the wound. In addition to your surgical debridement, where you take out all the bad humors, a local depot of antibiotics is often helpful to deliver a local high-dose to really sterilize the area – which I.V. antibiotics take some time to do. You speed up the process by delivering a high-dose antibiotic right to the site of involvement.

What are the complications associated with infected fractures?

Most commonly it’s a soft tissue problem. The reason that a lot of acute fractures become infected is the soft tissues have been severely traumatized. They’re battered and they’re bruised. They don’t have good blood supply because the blood supply has been damaged, and then the surgeon comes in, puts a big incision in it, and now compromises that soft tissue even more. It’s analogous to throwing gas on a fire. And that’s why for a lot of very severe articular injuries, we tend to put the patient in external fixators, let the soft tissues recover for ten days to two weeks before we go ahead and insult them again with an incision.

In addition, if you go back and you debride, sometimes that marginal soft tissue doesn’t survive, and then you end up with a soft tissue defect. That’s a problem because blood supply to help heal the fracture comes from the soft tissues and the muscles; the surrounding soft tissue envelope. Oftentimes you must do procedures that bring in healthy muscle, i.e. a new blood supply, to help fight the infection, to help heal the fracture.

What can patients do to help heal infected fractures?

The number one thing for infection, a total buzzkill if you will, for infection, is smoking. If you’re a smoker, the best thing you can do to help fight an infection or to heal your fracture – even if it’s not infected – is to stop smoking. Because smoking is a double whammy. You have the effect of carbon monoxide which decreases your oxygen carrying capacity, so your oxygen delivery to the tissue and thus the bone, is decreased dramatically. Nicotine in cigarettes is a direct poison to osteoblasts. By smoking a cigarette, you suffocate the cells and then you poison them. It’s a one-two punch.

The other thing that smoking does is it inhibits the formation of collagen. And collagen is the building blocks of bone, it’s like the rebar for cement. The cells come along, line up on the collagen bundles and then form bone. But the rebar must be there otherwise you don’t form bone. When a patient smokes, they don’t form any collagen. If a patient smokes a pack a day, the only time they aren’t smoking is at night when they’re sleeping. Most heavy smokers don’t sleep that well, because of the effect of carbon monoxide – they’re always awake. So, if you figure there’s 24 hours in a day and you’re only sleeping 4 to 6 hours, the only time you’re forming good bone is at night time. That’s why the data is very specific that it takes 3 to 4 times longer for a smoker to heal a fracture than a non-smoker and that’s because of the carbon monoxide, the nicotine, and the collagen inhibitory effect that smoking has. If you’re not delivering oxygen to the tissue, you’re not fighting the infection. It also has a vasoconstrictive effect that clamps down on the blood vessels and you’re not delivering antibiotic. So, number one thing, don’t smoke.

Number two, watch your diet. A lot of fast food, high carbs, low protein is also a buzzkill to fighting infection and healing your fracture.

Number three, taking your antibiotics when you’re supposed to and being compliant in your treatment.

But really the main thing would be avoiding noxious activity. If you’re taking steroids, we try to have to cut you back on steroid medication. Diabetics you can’t really do much about. You are dealt a difficult hand if you’re a diabetic; very difficult to fight infection because of the small vessel disease that diabetics have.

How important is it to know the pathogen that’s causing the infection?

There’s the acute infection where the wound is draining, and you take the patient back to surgery, you wash it all out, and you take deep tissue cultures. Swabbing the skin doesn’t really help you, it often leads you down the primrose path and gives you false information because everybody’s skin is highly contaminated with normal skin flora. Just swabbing the skin gives you false readings and may lead you to put someone on incorrect antibiotics. So, you do your debridement, you take deep tissue cultures, and then use your post-debridement cultures as a guide to the antibiotic that you use. Oftentimes, you don’t know, you have a suspicion. Most commonly it’s going to be a Staph because that’s the most common organism out there, but if the patient was in an unusual environment, say in water or in grass or a barnyard type situation, it may be a more virulent organism, such as a gram-negative-something that’s a little more vicious to treat.

In the case of a chronic infected non-union, you go in, you debride, you take out all the dead tissue, all the dead bone; and send that tissue off for cultures. By the time you’re going to do the definitive reconstruction, you know what bug you had and what bug you’re treating. So, it’s a little bit different, again depending on the chronicity of the pathology that you’re treating.

Does the risk of infection differ between open and closed fractures?

Yes, no question about it. We grade fractures based on the severity of the open wound. A little poke-hole is much less likely to be infected than a motorcycle accident where your leg is wide open. So, it goes on the degree of how open the wound is and how much soft tissue is missing or stripped off. You can have a very large skin incision but the muscle and the deep tissue, the periosteum, is intact with a small type of a fracture. Even though the wound is very big, the muscle and the soft tissues that provide the blood supply are still viable and won’t turn a hair.

On the other hand, you can have small laceration with a deep, impalement type wound that destroys muscle and deep soft tissue. There’s no healthy tissue around the fracture. Those are very prone to infection because of the lack of a healthy blood supply. It all comes down to how much blood supply, or the tissue that provides the blood supply, is available to help you. With closed fractures, usually the soft tissue is contused, it’s bruised, but it’s not missing, or it’s not shredded apart. A reasonable infection rate for a closed fracture, let’s say an ankle fracture that you fix, is probably less than one percent infection rate in a clean surgical environment. It should be less than one percent for a closed, clean surgery.

For a grade three, a bad open tibia where there’s a lot of muscle devitalization and in some instances where you’ve maybe torn the artery, infection rates can be as high as 25-26 percent. The amount of soft tissue damage is really what determines how badly they become infected or if they will become infected. It’s not necessarily how bad the bone is broken, it’s the surrounding soft tissue envelope that’s really the key as to the genesis of infection and how you treat it.

How do you grade fractures?

Fractures are usually graded on the size of the soft tissue injury. For instance, a classic grade one injury is less than a centimeter, which is very small; it can be just a poke hole, a small laceration, but it’s very small and there’s no deep tissue disruption. In other words, the bone just popped through the skin, and that’s it.

A grade two is more than a centimeter. It is bigger than a breadbox but smaller than a Mercedes Benz type thing.

A grade three is much larger. Grade three really means that there’s a lot of soft tissue stripping. It is usually more than two centimeters, but it really comes down to what’s underneath the skin incision. How much soft tissue stripping is there? The bad ones are graded as a grade three. Now if you can close that, in other words, you wash it out, you treat it and then you can close it, that’s called a three A. A three B means you wash it out, you’re missing so much soft tissue it can’t be closed, you must do a skin graft or a muscle flap – a secondary procedure to get the skin closed. So, it’s really based on soft tissue and how big the wound is.

How quickly will an infected fracture heal?

It’s a million-dollar question and if I had the answer I probably wouldn’t be sitting here. They usually take longer just because of the insult – they got an infection for a reason – maybe the blood supply wasn’t very good, maybe they’re a diabetic, so just by its very nature it’s going to take longer. Assuming you’ve sterilized the wound, you’ve cleaned up the infection, then normal healing time is not going to be routine; it’s going to take longer – and that varies from location to location.

For instance, an ankle fracture should be healed in about 2.5 to 3 months. An infected ankle fracture is probably going to be closer to 3 to 3.5 months, assuming you clear up the soft tissue.

A tibia fracture, especially a distal tibia – the average time for healing is about 4 months, that’s the average time; some of these go to 6, 7, 8, 9 months, to a year, depending on what’s transpired. I don’t have a magic number, I just know that if it’s not treated, they’re never going to heal.

Patients will know a difference right away, I mean, once you start to treat it and you get rid of the infection, a lot of the symptoms that they have will dissipate very rapidly. Their leg or their arm will feel much better, they’ll know that something has changed dramatically just by eradicating the infection.

How can reoccurrence of infection be prevented?

You must think about infection before you start to treat it. In other words, it starts with the evaluation of the injury and how bad is the soft tissues. If the soft tissues are very contused and bruised, you may not want to put an incision through it right off the bat because you have a pretty good idea that that wound may break down and be a nidus for infection. I think the best cure is to try to do as much preventative maintenance as you can prior to going to the operating room. A judicious evaluation of the injury and the soft tissues, and the timing of surgery is crucial.

Sometimes you don’t have an option, the wound is open, and you must go for it. Planning of the incision and the fixation appropriately so that you don’t devitalize a lot of soft tissue is important. The exposure is crucial, being judicious, operating right where you need to be and not doing a ‘grenade-o-plasty’ approach where you rip everything wide open – that’s usually bad.

Appropriate prepping of the patient in terms of the skin, prophylactic antibiotics given ahead of time, appropriate surgical technique, not using a lot of crushing instruments or tearing of the soft tissues is important. And then, of course, closure is also very important – making sure you have a watertight closure. If there is a lot of edema in the wound, using a negative pressure dressing to help pull out the excess fluid because edematous tissue doesn’t heal very well. Compressive dressings, post-operative I.V. antibiotics for the usual amount of time, and then nutrition and careful wound management and follow-up. Once an infection has occurred, then you’re on a whole different pathway of treating it rather than preventing it, so we try to do a lot of things ahead of the O.R. to really try to avoid dreaded complications.

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