Saturday, July 23, 2011

A Common Complication of Diabetes

A 40ish year old male patient came into the urgent care clinic to be seen.  I had seen him before on two other occasions, and we had quickly formed a friendly relationship with each other.  He was with his two daughters, as usual.  I had seen him once previously for cellulitis around his insulin pump injection site, and the second time he had come in with both of his daughters for ear infections.
“Well, hello again, Ed, which daughter is it this time who’s sick, Kate or Melanie?”
“Neither, it’s me.  My right ankle is sore and I’ve got this drainage coming from my previous surgical site.  I don’t know what it is.  Yesterday I noticed that I had a small blister at the site which I popped and yellow to tan fluid came out of it.  It quickly stopped and I put a band-aid on it.  Then again this morning some more tannish fluid came out of it.  I put a clean band-aid on it, but I don’t know what’s going on.  The drainage site is right over where a screw is, it was inserted when I had a car accident two years ago, and broke this leg in 3 places.  I have a rod in my leg as well as several other screws.”
Ed removed the band-aid and I could tell that there was a small amount of fluid that had drained from his leg.  I felt his right ankle and it was somewhat warmer than I expected.

Trauma to a extremity which leads to implantation of surgical hardware is one of the major risk factors for a bone infection, i.e. osteomyelitis.  Another risk factor is diabetes. 
Osteomyelitis can be divided into acute vs. chronic.  This is typically decided on the amount of time the patient has had the infection.  Acute is considered to be less than 6 weeks, chronic is considered to be longer than six weeks.  Another way of determining chronic osteomyelitis is based on the presence of a sinus tract.  If the patient has one, they invaribly have chronic osteomyelitis. 
Bones can becomes infected via the blood stream,or  contiguously (i.e. local spread from the surrounding muscle).

“Ed, I used to work in infectious diseases for two years.  I took care of all sorts of patients who had osteomyelitis.  One of the major risk factors for bone infections is hardware.  They are very conducive for bacteria to grow on. And small sinus tracts like the one you have on your ankle is a tell-tale sign that you have chronic osteomyelitis going on in the bone.  The tannish drainage tells me that the infection is due to one of the skin bugs called staphylococcal aureus.  It’s a common bacteria found in patients who have bone infections.  I need you to call your wife, advise her to meet you over at the hospital in the medical center.  I’m going to write down on a piece of paper, exactly what the nurse who will assess you, needs to know so that you get the attention you need from the emergency room physicians.  Okay?”
“Okay, how far up do you think my bone is infected?”
“The orthopedic surgeons will have to take out all of the hardware, you probably have an infection all the way up the rod as well as all of the screws are infected.  I don’t know what they will be able to leave you with so that you can walk, but they’ll have to decide on that.  Right now, you need to be in the hospital and quickly.  Let me know what happens, okay?”
“Sure thing.”
 I sent him to the closest academic medical center hospital that I knew had a very good infectious disease teaching service as well as a solid teaching residency program for orthopedics.
On the piece of paper I handed to Ed I had written:  This patient has chronic osteomyelitis of his lower right tibia, most likely caused by staphylococcal aureaus.  He has a draining sinus tract on the medial aspect of his ankle where a screw can be felt.   He has type 1 diabetes and is on an insulin pump.  He needs to be seen by orthopedics and infectious diseases services right away.  I then signed my name.  With that, I knew the nurse would not be able to discount what I had written down, whereas she would probably discount the patient telling her this same info, seeing that the sinus tract didn’t look that remarkable having only a mere band-aid over it. 
Ed was on his cell phone with his wife, as I handed him the note to give to the ER nurse.  He quickly left the clinic with his two daughters in tow.

Treatment of bone infections usually last for at least six weeks.  Patients are generally started on intravenous antibiotics and then if possible they are switched over to oral antibiotics, based on their bacterial cultures. 
Cultures of their sinus tracts is a poor corrollary to what is actually in the bone causing the infection.  The gold standard for osteomyelitis is to do a bone biopsy.  Plain films of the involved area are also usually done and are quite helpful.  They can show evidence of the bone infection via the separation of the outer bone lining (called the periosteum) from the bone itself.  Other forms of xraying that helps is to do a MRI or a CT Scan.  If the patient has hardware then you are unable to do a MRI or a CT scan, in this case you can do a bone scan, which is a nuclear imaging study. 
Initial antibiotics for this infection are used based on the usual bacteria that infects bones, i.e. skin bacteria (staphylococcal aureus, staphylococcal epidermis).  Additional antibiotics are then added in based on the results of the patient’s cultures.  They can also have gram negative bacilli or anaerboic (bacteria that live in the absence of oxygen) infections. 

I didn’t hear back from him for a while.  Two weeks later Ed, using crutches came into the clinic to talk to me.  
 “Well, if it isn’t Ed, you’re a happy sight for sore eyes.  Tell me what happened, I’m all ears.”
“First off, thanks for writing that short note for the ER nurse.  She read it, and immediately walked out of the exam room and came back in with one of the emergency room docs.  He took one look at my leg, felt it with his hand, and went over to the phone and paged the infectious disease service.  The infectious disease service resident or fellow, I don’t know which, was there within 30 minutes assessing my leg.  The next thing I knew they were working on my admission papers.  Within 24 hours of my admission, I had been started on IV antibiotics for the bacteria you mentioned, and the cultures came back positive for them, by the way.  They did several cultures of the sinus tract and a bone scan which came back all lit up from my ankle up to my knee where the rod ends.”
“Orthopedics saw me in the emergency room and they told me what you said, all of the hardware would have to come out.  I was on the IV antibiotics for almost a week at which time the orthopedic service finally decided it was safe for them to remove everything.  They told me that they wanted the infection under control before they went in.  The surgeon told me after the surgery, that when they removed the rod, that it was just oozing with fluid dripping off of it, which he said would come back positive for the staph bug, which it did.” 
“They also removed all of the screws.  Then they put this plastic inflatable tube inside my bone from which the antibiotics are slowly seeping out from.  I was told that the tube will continue to treat the inside of my bone with the needed antibiotics for six weeks.  After that the orthopedic service is going to go back in, and remove the plastic tube.  I have to stay on these crutches until after the plastic tube is removed.  I’m also on oral antibiotics, . . . Cipro I think is what it’s called, I take it twice a day.  Then I have to go back and see the infectious disease and orthopedic services every two weeks, until all of this clears up.”
“The infectious disease service told me that I was lucky to have come into the emergency room when I did.  The infection was already beginning to spread into my blood stream seeing that the first night in the hospital I spiked a fever and a blood culture they did became positive for the staph bug. “
“Look at where the orthopedic guys cut me open, see here at my knee and then also on my ankle.  I’m going to have all kinds of scars.  Oh well, I wanted that rod out of my leg anyway,  I just didn’t think it would end up being this way.”
“Oh, I also wanted to say thank you.  Had you not talked me into going to the emergency room that night, and had you not known which hospital I needed to go to, I know I would not have received the care I needed, for this nasty infection I ended up with.  I don’t think too many physicians would have known that a simple little blister, which was draining such a small amount of fluid would be a harbinger of something much worse.  So I just wanted to make sure that you know how grateful I am.” 
“Well I’m just glad that it all worked out and you’re doing much better.  Thanks for coming in and letting me know what happened.”
“By the way, how did you know that I would be infected with that skin bug, staph you call it?”
“The color of the drainage from your sinus tract gave it away.  Tan is always a sign of staph infections.”
Over the next few weeks, Ed fully recovered, got his ‘plastic tube’ removed and returned to work full-time.

This patient will have to be alert to any signs that his osteomyelitis has returned.  Any patient who an episode of chronic osteomyelitis (bone infection) is at a higher risk of having it return.  Pediatric (kids) generally do better overall with this type of an infection because their bone infections are generally spread from the blood and they are easier to clear up.  Pediatric patients also have a better blood supply to the bones and therefore are able to clear out their bone infections easier. 
Diabetic patients are the ones who end up with osteomyelitis of the foot bones, this is partially due to their having other medical conditions such as a lack of blood supply to the area, lack of sensation in their feet which then allows the infection to continue to spread because the patient doesn’t feel anything is wrong.  So if you are a diabetic, please keep an eye on your feet, and make sure to inspect them every night before you go to bed. 

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