Hey everyone,

Since we are almost done with senior research projects, I though it would be a good idea to share the importance and the benefits my research and other research projects similar to mine can have on people with TKA infections.

TKA infections, also generalized as periprosthetic joint infection (PJI) continue to affect patients, result in accelerated mortality, and consume approximately $1 billion of annual healthcare resources. A PJI can lead to a more surgeries, longer hospital stays, having to reside in nursing facilities, and more physical therapy. This can all become very costly for a person. While there is no known way to prevent PJI's from occurring, the next best thing is to diagnose an infection as soon as possible. An early diagnosis allows a surgeon to take action fast, and hopefully get rid of the infection before it grows into a more complicated one. Even if an infection is left untreated for a few weeks, the bacteria will adhere to the metal of the implant and form a biofilm. Once this biofilm has formed, the only good treatment option is the removal of the implant, insertion of antibiotic materials into the joint area, and then after many weeks, insert a new implant. This requires at least two additional surgeries from the primary replacement surgery imposing heavy financial and emotional tolls on the patient. Because diagnosing an infected knee replacement can be difficult, finding certain physical symptoms that are often accompanied by an infection or certain diseases that increase the chance of infection, may help physicians diagnose an infection earlier.

Komal

Hey everyone, I hope you all started your weeks off well. I have to admit, I do not have a whole lot to say about this week. I went through more patient charts and collected more information about each patients medical history and their hospital complications after surgery. I was planning on analyzing the data on Friday to share in blog post, but unfortunately, I was not feeling well that day and did not go to my internship.

But, I do want to talk about the direction my project is going. Initially, I mentioned in my proposal that my project would consist of aiding orthopedic researchers in developing an algorithm that would help doctors across the nation diagnose a TKA infection. My role has been collecting data, and inputing it into an excel sheet, so the researchers can use this information when developing an algorithm. I was under the impression this project would take a couple of months of collecting data, and then they would start working on an algorithm, but my on-site mentor informed me that they will be collecting data for a much longer period that a couple months. Since I do not know how to develop an algorithm myself, I will taking a different approach at analyzing this data myself. I will be using the data for two different reasons: first, I will use each patients medical history to see if certain diseases may increase a persons chance of developing an infection. For example, in last weeks blog post, I mentioned that based off the data I collected, patients with diabetes and/or hypertension were more likely to get an infection. Secondly, I will be using the hospital complications of each patient to see how often certain post-operative complications occurred in patients. Hopefully, there are certain complications happen more often and would be a greater indicator of infection. 

Thats all I have for today, but hopefully I will be able to share more trends later this week. See you on the next blog post!

Hey there, 

I hope you all had a lovely week. I had a very busy week that included family gatherings, an eight hour track meet, and, of course, my internship. But I can’t complain, I enjoyed each event, and I got to spend a lot of time with my baby cousin, who is almost 11 months old.

At my internship, I continued to look through patient charts and collect data. I have noticed things like nearly every single patient with a TKA infection has hypertension (high blood pressure). I have done some research on hypertension, and found that 64% of men, aged from 65-74, are hypertensive and 69.3% of women, aged 65-74, are hypertensive. Also, 66.7% of men ,aged 75 and older, are hypertensive and 78.5% of women ,aged 75 and older, are hypertensive (http://www.cdc.gov/bloodpressure/facts.htm). So far, 84% of the patients with a TKA infection are hypertensive. Using this information, doctors can inform patients with hypertension before the surgery, that they have a slightly higher risk of getting an infection. In the future, as I collect more data, I will distinguish which percent of men versus women have hypertension. 

I have also noticed a high amount of patients who have diabetes. According to American Diabetes Association, 25.9% of Americans aged 65 and older have diabetes, while 41% of the patients with a TKA infection have diabetes. This shows that people with diabetes have a higher risk of infection.

One thing I wish I had access to was patients who had a total knee arthroplasty surgery, but never got an infection. This way I could collect data and see what percent of patients did have hypertension and/or diabetes, but never got infected. But, unfortunately, this is not an option for me, and it will remain one of the flaws of my project. 

In the following weeks I will be sharing more data with you guys! See you then!

Komal Majhail

Hello again,

On last weeks post I talked about three laboratory tests: a white blood cell count, a c-reactive protein (CRP) count, and a erythrocyte sedimentation rate (ESR). As I said in the last post, I have found that these three test are usually the first tests to be ordered when their is suspicion of an infection. But if the results are elevated, doctors can not conclude a patient has an infection quite yet, they must proceed with laboratory tests that tend to be a little more invasive, such as a knee aspiration (aka arthrocentesis). You might be wondering, whats the point of the first three tests if you can’t even use them for diagnosing an infection. Well the point is to confirm a doctors suspicion that the knee is not doing well with the prosthesis, and that much more invasive clinical procedures and laboratory tests need to be performed. 

A knee aspiration is the clinical procedure of using a syringe to draw fluid from the knee. As you can imagine this is much more painful than getting your blood drawn (a blood sample is all that is needed for the CRP, ESR, and WBC count tests). I will go more in detail about knee aspirations and how they pertain to TKA infections after mentioning some trends I have noticed. 

I have seen that a knee aspiration is usually the next step after the CRP, ESR, and WBC count tests. But, sometimes the knee aspiration is the first step, and this could be because the infection is a bit more obvious in that patient, or because the laboratory test results were never imported into the patients chart (missing information is one of the flaws of this project). 

Anyways, the fluid from knee aspirations are sent to a laboratory where the fluid sample is placed in a dish and watched to see if bacteria, fungi, or viruses grow. If these germs are detected, than there is a strong chance of an infection. 

In an earlier post, I mentioned a certain set of criteria many doctors follow when diagnosing an infection. I will include it in this post too, so you don’t have to go back. 

1) There is a sinus tract communicating with the prosthesis; or
2) A pathogen is isolated by culture from at least two separate tissue or fluid samples obtained from the affected prosthetic joint; or
3) Four of the following six criteria exist:

a) Elevated serum erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) concentration,

b) Elevated synovial leukocyte count,

c) Elevated synovial neutrophil percentage (PMN%),

d) Presence of purulence in the affected joint,

e) Isolation of a microorganism in one culture of periprosthetic tissue or fluid, or

f) Greater than five neutrophils per high-power field in five high-power fields observed from histologic analysis of periprosthetic tissue at ×400 magnification.

Number 2 and letter e are both talking about knee aspirations. If a pathogen is isolated it means that something grew in the dish and there is a strong chance of infection. Based on this set of criteria, if a pathogen is isolated from two separate fluid samples, than it is safe to say the patient has an infection. But if only a single fluid sample grows a germ, than three other criteria must be met to diagnose a patient with a TKA infection. 

I’m going to stop here, but In next weeks blog I will go over the last few laboratory tests that are used in diagnosing a TKA infection. 

See you then, Komal.

Hey everyone,

This week I went through more patient charts, but I want to hold off sharing the trends that I have noticed until I gather a bit more information.

Since I have only mentioned the names of a few of the laboratory tests that are normally ordered when there is suspicion of infection, this week I decided that I would introduce the first three tests that are usually preformed in more detail.

The first two tests I want to talk about is the Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP) tests. These tests are usually the first ones doctors order when their is suspicion of infection. Both tests are different ways to measure for inflammation. This ESR test measures the rate at which red blood cells sediment in a period of one hour. This test is done by taking a sample of blood from a patient and putting it in a tube. Then the tube will be placed vertically and allowed to sit, untouched, for period of one hour. During this hour the red blood cells will sink to the bottom of the tube, and the plasma will rise. The more the red blood cells sink, the greater the inflammation.

As seen in the picture, there are five samples of blood from five different patients. The red blood cells in the third tube have settled to the bottom of the tube faster than the red blood cells in the other tubes. This indicates that the third tube has the highest level of inflammation.

The CRP test measures for inflammation by determining how much c-reactive protein is in the plasma of a patients blood. The level of c-reactive protein rises when there is inflammation throughout the body. These two tests are helpful indicators of infection, but the problem with these test is that it only indicates that their is inflammation somewhere in the body, it cannot pin-point the exact location of inflammation. So if a patient has a cut, which will cause inflammation, than an ESR and a CRP test could give a false positive result. These test are especially not useful for patients that have rheumatoid arthritis (RA), since RA causes inflammation, it will most likely give a false positive result.

Another blood test that is usually ordered with the ESR and CRP test is a white blood cell count. Since white blood cells fight infections, an abnormally large presence of white blood cells would be a strong indication of infection. But similarly to the ESR and CPR tests, if the patient has other reasons for a high white blood cell count, such as being sick, it could give a false positive result. 

While the ESR, CRP, and WBC tests have their issues, they are still often the first few tests a doctor will order. These laboratory tests are only part of the first step to diagnosing an infection. If these tests all come back elevated, doctors generally still do not diagnose a patient as having an infection, instead they order a few more laboratory tests. Since this post is starting to get a bit long, I will talk about the following steps to diagnosing an infection on the next blog post. 

See you then, Komal

Hi everyone,

So as I said last week, I have been having trouble going through patient charts, and finding all the information I need to gather. The problem was that I was given certain laboratory results, co-morbidities, hospital complications, and medications to find, but sometimes I couldn’t find them. For example, there are about 8 different laboratory tests I was told to look for, and I was told I wouldn't find every single test result for each patient because doctors usually don't have to order that many laboratory tests to make a diagnosis. But, for some patients I will be able to find four or five tests and others I wont be able to find a single one. I thought I wasn’t able to find any laboratory tests because I wasn’t looking in the right places. So I would keep searching, but with no luck. It turns out, there are patients that don’t need any laboratory test done to diagnose an infection. 

This week I had help from an orthopedic physician assistant, Neil, who also does research with the MORE Foundation. He showed me how he goes through the charts and all the different places you can look for certain information. Initially, I was only looking at the documents labeled laboratory test for the results, but sometimes doctors put the test values in hospital consults. He also told me some patients won’t have laboratory tests done and to explain why he shared a link with me. To summarize, the link explained that there is no single set of diagnostic criteria for a periprosthetic joint infection (PJI), but MSIS (Musculoskeletal Infection Society) proposed that a PJI exists when:

1) There is a sinus tract communicating with the prosthesis; or
2) A pathogen is isolated by culture from at least two separate tissue or fluid samples obtained from the affected prosthetic joint; or
3) Four of the following six criteria exist:

a) Elevated serum erythrocyte sedimentation rate (ESR) and serum C-reactive protein (CRP) concentration,

b) Elevated synovial leukocyte count,

c) Elevated synovial neutrophil percentage (PMN%),

d) Presence of purulence in the affected joint,

e) Isolation of a microorganism in one culture of periprosthetic tissue or fluid, or

f) Greater than five neutrophils per high-power field in five high-power fields observed from histologic analysis of periprosthetic tissue at ×400 magnification.

This link was helpful because now I can understand what a doctor is thinking when looking at a possible infected knee. For example, in the case that their is a sinus tract communicating with a prosthesis, then no laboratory tests was needed to be ordered, which means I probably won’t find any. 

Now that Neil helped understand the charts a bit better, I’ll be starting back at patient one to make sure I didn’t leave out any important information form when I initially reviewed the charts. 

Thats all I have for today, thanks for sticking around, and see you next week!

Hello everyone!

This week I was finally able to start working on my project. I was given 300 patients who have been diagnosed with an infection, and my job is to go through all of their charts. First, I am looking for co-morbidities that may have increased their chance of getting an infection, for example research shows that kidney disease increases a patient’s chance of getting an infection. But their is a lot of disagreement among researchers about which co-morbidities truly increase a patients chance of infection. For example, some doctors believe obesity is a co-morbidity while other doctors do not. I will be looking at the 300 patients that I received, and document any information that could be a co-morbidity for infection. Once doctors agree upon a list of co-morbidities, they will be able to inform their patients of their individual risk of getting an infection before getting surgery. This way a patient has a better understanding of their risk. The incidence of infection is between one to two percent, but if a patient has kidney disease, than their chance of infection is obviously going to be slightly higher. 

I will also be looking at complications the patients had after surgery, such as stiffness, pain, or wound drainage. From the patient charts that I have through so far it seems like a sudden increase of pain, wound drainage, and purulence are a few of the key indications of infection. 

The last thing I will be looking for are the lab results for each patient. The three main tests doctors will usually order when there are indications of infection are a white blood cell count, a erythrocyte sedimentation rate (ESR), and a C-reactive protein test (CRP).

Next week, I hope to be able to share some of the co-morbidities, complications, and lab result values that would be found with an infection. 

Until then,

Komal Majhail