Compact substance and spongy substance
The bone itself is composed of two different substances. In fact, they are not that different, because what really differentiates them is the spaces between the cells:
In the compact substance , as the name says, the cells are very close to each other, so that there is not much space between them. This type of substance is found on the ends of long bones (epiphyses), as well as on the external parts of short / small bones, as it provides greater protection against impacts.
However, if the bone were entirely compact, it would be very heavy and hinder locomotion. Besides, it takes space for the blood to circulate, isn’t it? Therefore, there is the spongy substance , found in the innermost portion of the epiphyses, surrounding the medullary canal. It is also found within small bones, even those that have no spinal canal.
Inside the bone, there is a channel that surrounds the so-called bone marrow , a gelatinous tissue in which the production of white blood cells (leukocytes), red blood cells (red blood cells) and platelets occurs. Ironically, leukocytes are the body’s main defense against infections, but they may not be of much help when osteomyelitis meets the spinal canal.
As a curiosity, erythrocytes are responsible for transporting oxygen in the blood, while platelets assist in blood clotting in case of wounds.
Now that you understand what bones are made of and what their main functions are, it’s easier to understand how osteomyelitis can happen. Just keep reading!
Causes of osteomyelitis
The biggest villain when it comes to osteomyelitis is a bacterium called Staphylococcus aureus , which is found naturally in the most favorable place possible: our skin. There are not many reasons to try to get rid of this bacteria, since it is quite harmless most of the time. The problem is when it enters the bloodstream, which can infect various tissues where it can cause harmful effects.
Other microorganisms can also cause osteomyelitis, such as Mycobacterium tuberculosis , which causes tuberculosis , in addition to fungi. Yes, fungi! It is strange to think that our bones can be infected by fungi, but there is a very simple reason for this: the infection starts elsewhere.
How does the infection occur in the bones?
There are three ways in which bacteria and fungi can get to the bones, and none of them are pleasant. At first, it is logical to think that this can only occur when a bone is exposed and, yes, this is one of the means, but not the only one.
The main ways in which microorganisms reach bones are:
Remember that bones are living tissue and need to be irrigated with blood to function properly? Well then, the bacteria and fungi that have entered the body (in some way) can walk free through the circulation and take shelter in the bones. There, they begin the process of proliferation, initiating a bone infection.
Infection in structures close to the bones
Just as microorganisms can be taken directly to bones through the bloodstream, they can also lodge in nearby structures, such as muscles and connective tissue. As these organisms proliferate, they can easily reach the periosteum and reach the bone.
It is worth remembering that this type of infection can originate in the teeth and gums. Therefore, it is an invitation to reflect better on your oral health and take better care of it!
When the bone is exposed due to a fracture, surgery or perforation, it can come into contact with bacteria and / or fungi and start an infectious process. Unfortunately, one of the easiest ways to be infected is during orthopedic surgeries, performed precisely to correct a problem that the bone was already presenting.
How does osteomyelitis evolve?
As we saw above, the infection can happen in many different ways. Regardless of how it happened, the bacteria are not content to reach the surface of the bone and continue to proliferate to reach deeper and deeper.
In this way, the microorganisms move from the periosteum to the compact substance, then to the spongy substance and, finally, reach the bone marrow. In response to this invasion, the bone marrow swells and swells, putting pressure inside the bone and compressing the arteries and veins present there.
Behold, the death of bone tissue occurs. Because of the compression, the blood is no longer able to oxygenate certain parts of bone and they start a process of necrosis. As stated earlier, this is quite complicated as it is in the bone that important parts of the blood are produced.
Another possible situation is the entry of bacteria into the bloodstream through the release of minerals and / or new blood cells that the bone produces. This can lead to a generalized infection, when proliferation occurs in several organs at the same time, and the chances of survival in these cases are not very high.
It is worth remembering that bacteria do not stop proliferating unless something interferes in this process, as is the case with drugs and the immune system itself, when it is able to fight against infection. This means that unless something is done, the bacteria will continue to multiply and take other parts of the bone that are still healthy.
Is osteomyelitis transmissible?
Osteomyelitis is not transmissible from person to person. However, the bacteria that cause the disease can be transmitted , but this is very difficult to happen without a blood transfusion, or the person uses drugs or medication intravenously. Finally, whether this transmission will result in osteomyelitis depends on several factors.
There are many risk factors that can contribute to a person having osteomyelitis. Most of them are related, as expected, to poor hygiene habits and untreated conditions. The main risk factors are:
Recent injuries and fractures
Bone exposure alone is a risk factor for bacteria to contract. However, people who do not take care of these injuries can increase the chances of developing osteomyelitis.
Medical procedures with catheters
As much as, in the hospital, everything is done to keep the environment free of microorganisms harmful to our health, medical procedures that use catheters, such as the urinary catheter, are a major risk factor for the entry of bacteria and other organisms in the bloodstream.
Another procedure that is very “guilty” for the proliferation of bacteria in the patient’s bloodstream is hemodialysis, a procedure in which people with kidney failure have their blood filtered by machines.
Not infrequently, drug addicts use drugs intravenously, that is, they use syringes with unsterile needles to inject the drug themselves. Often, these needles are even shared. The use of illegal drugs is therefore a major risk factor for contracting any type of infection.
Weakened immune system
Patients with a weakened immune system are more likely to get infections, either from fungi or bacteria. It is not just HIV- infected patients who suffer from a weakened immune system: patients who are undergoing chemotherapy or who have been on corticosteroids for a long time are also at risk.
Diabetes , ischemia (lack of blood supply to the tissues) and other circulatory problems are a risk factor for osteomyelitis, since the lack of oxygen causes necrosis and deep wounds in the skin that can be easily infected.
Surgeries and orthopedic prostheses
In orthopedic surgeries, in addition to leaving the bone exposed for some time, materials can be used to pierce the bones in order to perform a repair or place a prosthesis. Any and all surgery is a risk factor for infections, but orthopedic surgeries are the main ones for directly touching the bones.
People who have had prostheses for some time are also at increased risk, as infections can settle and remain quiet for a long time, revealing themselves only weeks or months later. In such cases, the treatment is more complicated, but it can still give good results.
Types of osteomyelitis
Osteomyelitis can be classified according to the time or the source of the infection:
Classification according to time
When the infection has less than a month (4 weeks) of development, it is called acute osteomyelitis. It is ideal that treatment is started at this stage, as there is a better prognosis (greater chances of total recovery).
Sub-acute osteomyelitis is called when the infection develops for 1 or 2 months.
If, due to some bad luck or simple lack of attention to signs and treatment, the patient allows the disease to progress for more than 2 months, osteomyelitis becomes chronic. In such cases, treatment may not be as effective and may only be able to maintain control so that the infection does not spread.
Classification according to origin
It refers to osteomyelitis caused by infections in the bloodstream, that is, which comes through the blood itself. It is more common in children than in adults.
It occurs after any type of trauma, such as fractures and deep open wounds on the skin. It can also develop after surgical procedures, especially when they involve metallic prostheses.
Vertebral osteomyelitis is one that affects the spine. It is usually the product of a blood infection, although it can also be contracted during surgical procedures. It usually occurs as a consequence of infections in the urinary or respiratory tract, in the mouth or injection site, in addition to endocarditis (infection inside the heart wall).
Osteomyelitis in children
In general, when children have osteomyelitis, it is of hematogenous origin, that is, it occurs through the presence of bacteria in the bloodstream. For this reason, the main bones affected at this age are the femur (thigh bone), tibia (leg bone) and humerus (arm bone). The first symptoms are fever and, some time later, bone pain.
If your child is complaining of bone pain, it is important to take him to the doctor as soon as possible in order to establish a diagnosis and start treatment early, with a greater chance of a good prognosis.
Sudden fever, bone pain and swelling are just a few signs, not always present, that there may be a bone infection. The symptoms depend a lot on the time of infection, as well as the form in which it was acquired.
In acute infection, the first symptom is usually a sudden fever . However, it is not always present and, therefore, the disease is only noticed when there are other symptoms. In the tissues surrounding the bone, there may be:
- Swelling (edema);
- Local heat.
If the infection occurred shortly after surgery, it is possible that the stitches will open and the wound will start to expel an abnormal discharge.
When the disease passes to the chronic stage, the signs are milder, but it is not possible to ignore them. This is because there is persistent local pain , which does not relieve with rest or compresses. Painkillers are hardly effective.
Another sign that is impossible to ignore is a fistula, a wound that opens from an abscess , leaving a purulent secretion, often smelly.
It is worth remembering that these symptoms appear at the site of the infected bone. Therefore, when the infected bone is the humerus, pain, swelling and redness will appear in the individual’s arm. In addition, the disease may simply be asymptomatic , that is, it may not show any sign of its existence for a long time.
How is osteomyelitis diagnosed?
If recognizing the symptoms of osteomyelitis can already be a challenge, the process for reaching the diagnosis is not very encouraging. This is because several tests may not show any changes for a long time, as well as others can result in false negatives. In addition, there is no specific test that can diagnose the disease, and tests are often done just to cross it off the list of possibilities.
The good news is that being aware of some risk factors can make the process a lot easier, as it is difficult to think that it is something else when the individual has just undergone orthopedic surgery, isn’t it?
Either way, several tests are done to identify the disease and its cause. Are they:
Two important tests for a correct diagnosis are ESR and C-reactive protein . These two tests are done using blood samples from the patient, and are mainly used to identify an inflammatory process.
ESR measures the time it takes for red blood cells to settle to the bottom of the test tube, whereas C-reactive protein is more abundant in the blood when inflammation occurs. High scores on both exams mean that something is wrong.
The doctor, usually a general practitioner or infectious disease specialist, may also order a white blood cell count . Remember that leukocytes are the body’s main defense in case of infections? When their levels are high, it is a sign that, most likely, there is some microorganism proliferating somewhere.
None of these tests is able to diagnose osteomyelitis by itself, but they are very useful to rule out this possibility when the results are normal.
Other tests that the doctor may order are radiographs to check for bone changes. Each modality has its advantages and disadvantages:
Computed tomography and magnetic resonance imaging
These two exams provide clear images of the inside of the body, especially in the form of “slices”, as if someone had cut the body in half and we were looking directly at this cut. In this way, it is easier to find anomalies than on a regular X-ray .
The problem is that none of these tests is able to detect bone changes in the first 2 to 4 weeks of infection, being unreliable for the diagnosis of acute osteomyelitis. In cases of chronic osteomyelitis, they can help to identify an infection in the bones.
It is the main choice of doctors to diagnose osteomyelitis. The procedure consists in the application of a radioactive substance that serves as a contrast and sticks to the bones, which helps in the production of clear images of any anomaly.
However, scintigraphy is not able to differentiate an infection from other bone changes. Therefore, an alternative is leukocyte scintigraphy , in which the patient receives an injection that highlights the leukocytes in the image, in order to help distinguish between infections and other conditions.
The best way to diagnose osteomyelitis is biopsy . This examination consists of taking a sample of the tissue that is sent to the laboratory, where it is analyzed and it is possible to determine whether or not there is an infection. It is also through it that cultures can be made, to find out which microorganism is responsible for the infection.
The biopsy can be done with blood, pus, joint fluid and bone tissue. For diagnostic purposes, the best option is the removal of bone tissue, since it is it that is of interest to be investigated. Taking a graft from any other tissue can give false results, as other bacteria may be circulating in other parts of the body.
In order to find out which infectious agent is present in the patient’s body, the biopsy is sent to a laboratory in which biomedical practitioners create an environment conducive to the proliferation of the organism. All of this is done in a controlled manner, so stay calm, as the chances of starting a zombie apocalypse in such spaces is really very small.
When the culture (the proliferation) arrives at a good size so that the biomedical doctor can find out what the microorganism is, he ends it by using antibiotics . In the report, the species found is mentioned and the infectious disease physician can, in short, prescribe a treatment for the patient.
As mentioned earlier, some tests are done precisely to rule out the possibility of being osteomyelitis, not to diagnose it. This is because some symptoms may be related to the following conditions:
- Prosthesis loosening due to non-infectious cause;
- Shortening of the limb;
- Joint wear;
- Muscle atrophy;
Each of these alternatives should be studied and treated as soon as they are diagnosed, as they can bring complications and a lot of suffering to the patient.
I have a prosthesis and I was diagnosed with osteomyelitis, now what?
First, don’t despair. Even if, most likely, you have to remove the prosthesis, this does not mean that everything is lost. There is a possibility to eradicate the infection just as in the case of people without prostheses, the process is just a little more complicated.
As is known, having orthopedic prostheses is one of the risk factors for osteomyelitis, even if the operation has been performed for months. That is why treatment can be difficult: the proliferation of bacteria occurred in a silent manner and, when the infection manifests, there is a risk that conventional treatment is not enough.
Often, the removal of the prosthesis is necessary, and it is common that it is simply replaced by another. Therefore, there is no reason to worry, especially if the infection is in its early stages.
Is osteomyelitis curable? What is the treatment?
At first, it can be said that osteomyelitis is curable . This is because the treatments available, when done correctly, are able to kill the bacteria and end the infection.
However, if the patient takes too long to go to the doctor or does not use the medication correctly, the bacteria may become resistant and, in such cases, a complete cure may not be possible.
It is worth remembering that total cure is more likely in cases of acute osteomyelitis than when the disease is chronic.
The main drugs recommended for osteomyelitis are antibiotics, drugs developed especially to kill bacteria. There may be some difficulty in this process, since bacteria are living organisms that adapt and create resistance to treatment.
It is worth remembering that each antibiotic is capable of acting on certain species of bacteria and there is no one that is effective against all of them. For this reason, the culture exam is so important: knowing the organism you are dealing with is the key to finding the means to destroy it.
Some examples of antibiotics that the doctor may prescribe are:
- Oxacillin ;
- Cefazolin ;
- Vancomycin ;
- Ciprofloxacin ;
- Levofloxacin ;
- Ceftazidime .
In the rare cases where the infection is caused by a fungus, antifungals are administered for several months.
How does drug treatment work?
If you have been diagnosed with osteomyelitis and doctors want to hospitalize you, don’t be afraid. This is because the beginning of the treatment is often done by the intravenous route, that is, you receive the medication directly in the veins. Doctors often choose this route because it is the fastest and takes effect in a few seconds. When it comes to bacterial infections, every second counts.
Due to the possibility of allergies and difficulties in application, this type of administration is only done in hospitals and health centers.
After some time receiving the intravenous medication, doctors can prescribe antibiotics in pills. This oral treatment lasts for a longer time, totaling a treatment time between 4 and 8 weeks. That if everything goes well.
There are cases, as in chronic osteomyelitis, in which the culture of bacteria inside the body is in a very large size and only 8 weeks of treatment is not enough to eradicate the infection. In these situations, more aggressive approaches may be necessary, as the duration of drug treatment goes from weeks to months.
Depending on the extent and time of infection, the most recommended alternative is surgical cleaning . In it, all the foci of infection are removed, such as prostheses, abscesses and dead parts of the bone (where the blood no longer reaches). This is important because, where there is no blood supply, antibiotics do not arrive either.
Some surgical procedures to be performed are:
One of the simplest procedures is to drain any fluids and pus that may have accumulated due to the infection. Abscess drainage is also done at this stage.
In debridement, the surgeon removes as much damaged bone as possible. Pieces of bone that have suffered injuries and / or necrosis are removed, along with a healthy border to ensure that bacteria possibly present in that region do not pass on to other parts of the bone.
Restoration of blood flow
Due to debridement, an empty space can be left in the bone. This space needs to be filled in order for blood flow to circulate normally. Therefore, the surgeon can use other pieces of bone or other tissues, such as muscle and skin, in order to restore this flow.
In some situations, a temporary filler may be used until the patient is healthy enough for the bone graft.
Removing foreign objects
Anything that the body does not recognize as its own is a foreign object. Prostheses, plates and orthopedic screws must be removed. This is because the presence of such objects can hinder the body’s recovery.
Ultimately, an amputation can be performed to prevent the infection from spreading further.
Do I really need to remove my prosthesis to fight infection?
Unfortunately, in most cases, the answer is yes, you need to remove the prosthesis.
When the bacteria reach the bone and / or the prosthesis, they form an invisible layer (called biofilm), resistant to antibiotics, where they continue to multiply. This is not bad for the prosthesis itself, but continuing with it can be dangerous for the patient.
If abscesses and dead parts of the bone are cleaned and the prosthesis is still not removed, the infection may return, since one of the foci of infection (the prosthesis biofilm) has not been removed. In addition, removing only the biofilm borders on the impossible – due to resistance to antibiotics – and, therefore, the most common is to replace the infected prosthesis with a new one.
The prosthesis can rarely be maintained. These cases happen when the treatment starts very quickly and there is no time for the bacteria to form the biofilm.
Amputation can be an option when the infection is in any of the limbs (lower or upper) and is not resolved with the use of antibiotics and surgical cleaning.
Adapting to life without a limb can be a very complicated task, but this alternative is the best one to prevent the infection from spreading through the body.
When treatment is difficult …
And when are there technical difficulties in the treatment? There are patients who cannot undergo surgery because they are malnourished and / or anemic, among other complications that prevent the surgical procedure. What to do then?
Unfortunately, in these cases, the use of antibiotics is prolonged and there is a very high risk of bacteria becoming resistant to the drugs used. We can say that, in certain situations, there is no prospect of a cure .
Why treat then? It’s simple: to avoid complications.
Although, in many cases, the infection cannot be eradicated, it can be contained. In addition, a medication regimen can be used to keep the infection under control while preparing the patient for surgical cleaning. This preparation seeks to improve the patient’s conditions to survive the operation and can be done with medications and diets that treat impeding conditions, for example.
Treatment in incurable cases seeks, mainly, to prevent sepsis (generalized infection) and to relieve symptoms of the infection that may be causing the patient to suffer. Among the main concerns regarding this treatment is, as is already known, resistance, in addition to the side effects of antibiotics that are usually quite unpleasant.
Ultimately, treatment without a prospect of cure can lead to the same outcome as being left untreated: when the bacteria creates resistance, it starts to proliferate normally, and all the work done to avoid complications goes back to square one.
What are the main complications of osteomyelitis?
Despite being easily prevented with the right treatment, complications from osteomyelitis can be extremely serious:
Septic arthritis (joint infection)
Because osteomyelitis is very close to the joints, it can take the bacteria to the synovial fluid, present within the synovial joints. This type of joint is found in joints that provide greater movement, such as the knee, elbow, shoulder and even the fingers.
When the bone marrow is reached and inflamed, there is a compression of the blood vessels, which leads to the death of bone tissue.
In the case of children, osteomyelitis can hinder bone growth. That’s because one of the tissues that most suffer from the disease is the epiphyseal plaque, also known as growth plaque, found on the ends of long bones.
Epiphyseal plaques are responsible for bone growth, being calcified over time. With infection, these areas can lose their function.
When osteomyelitis opens wounds on the skin to drain pus, the areas around the lesions are more likely to develop uncontrolled growth of squamous cells, resulting in skin cancer .
When the infection reaches the bloodstream, the microorganisms spread to various tissues, resulting in infection and generalized inflammation. It is worth remembering that sepsis is highly fatal and difficult to treat.
Due to the resistance of bacteria and the possibility of sepsis, vital organs can be infected. When things get to that point, osteomyelitis can easily lead to death.
How to prevent osteomyelitis?
If you already take care to avoid any kind of infection, you don’t need to do much more than that in order to prevent osteomyelitis. However, if you want tips for staying safe, the following steps should be taken:
- Carefully wash and clean cuts and open wounds on the skin;
- Always consult a doctor when you encounter wounds that do not heal;
- Clean and dry amputees, especially before placing prostheses;
- Move frequently when bedridden and / or seated and maintain skin hydration to avoid pressure ulcers;
- Diabetics should keep their feet clean and hydrated, in addition to preferring socks and appropriate shoes, in order to avoid diabetic feet;
- Wear suitable protective clothing and equipment when playing sports and other physical activities.
Did you like to know more about osteomyelitis? Great! Now do your part and be forewarned! Don’t forget to see a doctor whenever you suspect something, okay?
Share this text with your friends and family so that more people know about the disease, how to treat it and the importance of having a correct diagnosis. Any questions, you can contact us and we will respond.