Today we are going to talk about Osteomyelitis Right We'll talk about its pathology as well as its relevant clinical medicine Right So, first of all, what is meant by osteomyelitis Osteo means bone myelos mean bone marrow Right, Itis mean inflammation So, what is osteomyelitis? Inflammation of bone and bone marrow Right, so what is osteomyelitis? Inflammation of bone and yes bone marrow But Its almost always due to infective organisms Right So basically it should be considered a infection of Bone and bone marrow So what is osteomyelitis? osteomyelitis is inflammation of bone and bone marrow which is virtually due to Its almost always due to infective organisms Right Most commonly, these are either pyogenic Or non pyogenic Non pyogenic infection of bone or bone marrow Now Most commonly, either it is pyogenic or non pyogenic Pyogenic mean pus forming.There are bacteria which are involved in microbe which are involved which lead to the formation of pus Is that right? And non pyogenic organisms are those organisms when they damage the tissue But they don't produce the pus Now In those microbes which produce pyogenicc osteomyelitis The most important and most common is staph aureus Staph aureus In 80 to 90 percent of 80 to 90 percent of the culture positive cases are due to Staphylococcus aureus Right And then there are many other pyogenic organism which I will discuss later in detail Right But in the beginning, I just want to put in your mind the most common organism is Say it loudly Staphylococcus aureus Right It is the most common organism, why? It is , you need to remember that because when you start when you suspect a case of osteomyelitis And before the culture and sensitivity reports come You have to start the antibiotic therapy empiric antibiotic therapy In that case, The drug should cover staphylococcus aureus Right, later on, I will tell you There are certain conditions in which we suspect some specific type of organism to be present more commonly For example, later on I will discuss that patient with sickle cell disease They can have osteomyelitis due to staphylococcus aureus And also, they can have osteomyelitis very commonly due to salmonella Is that right? In the same way, If i talk about osteomyelitis in adult in sexually active persons It maybe due to Neisseria gonorrhoeae Right so these special conditions and their associated micro microbe I will discuss later In the beginning, you just remember that most common organism producing pyogenic osteomyelitis is Staphylococcus aureus and most common organism which produces non pyogenic osteomyelitis is mycobacterium tuberculosis myco-bacterium yes tuberculosis even though there are other organisms as well Fungi can also produce osteomyelitis but again most common organism in non pyogenic osteomyelitis is mycobacterium tuberculosis and when mycobacterium tuberculosis involve the vertebrae Spine The condition is called pott's disease when mycobacterium tuberculous, right, involve which bones? Vertebrae Right Spine then condition is called pott's disease Right Now Question is that bones are usually deep They are covered by the skin And some soft tissue and a very important membrane which protect the bone from the infections that is periosteum The bones are protected so well then how the organisms reach there? How the organism produces inflammation there? Right It means that how the next point which we should discuss that is that Root of arrival of organism That how the organism reaches to target bone to produce osteomyelitis Entry Root of entry or arrival that how organism reaches the specific bone to produce osteomyelitis Especially in children, the commonest pathway is haematogenous right The most common is haematogenous pathway Haematogenous root It is common in children and it can also occur in adult Right That organisms which produce bacteremia which produce bacteremia they may get enter into bone Especially in children, the most common part of the bone Let's suppose, this is a long bone And as you know in children this is a growth plate epiphyseal plate Here is also epiphyseal plate Right Now In children,long bones have special area where bone is growing This part is diaphysis here it is epiphysis and this part of the diaphysis which is contributing to the growth of the bone This is called metaphysis Right What is this? Diaphysis Right And that part of the diaphysis which is growing It means the ends of the diaphysis which are growing in children growing children, these are called Metaphysis and upper part is, yes, epiphysis A little detail and here is articular cartilage Here it is articular cartilage and here is a very tough membrane over it What is this membrane? periosteum Right, covering the bone Again what is this membrane periosteum And here in the diaphysis There is a shaft, there is a cavity This is called medullary cavity where usually there is bone marrow, right medullary cavity inside the medullary cavity, it is also lined by a membrane And this membrane is not called periosteum This membrane is called endosteum What is it called? endosteum Right But what I want to especially mention that this part of bone here Right And this part of the bone This is the growing part of the diaphysis which is just under the growth plate or just under the epiphyseal plate This part is, yes, metaphysis Why I am so much stressing on the metaphysis? There is a reason for that In children the most common site in the bone to get involved in osteomyelitis is metaphysis Later on, I will explain why? Actually, metaphysis has very peculiar type of blood flow And it has a very high, high level of blood flow It is highly vascular Right and ,later on, I will tell you vascular arrangement here predisposes this part of the bone that bacteria which are circulating in the blood they love to settle over here especially staphylococcus aureus Is that right? So in children the commonest site, the growing children, the commonest site for osteomyelitis is Say it loudly metaphysis of course of the long bones Right But in the adult, of course when you are adult These growth plates disappear There is no more metaphysis And it is no more so vascular Is that right? But in the adult also, hematogenously from a distant site of infection Bacteria can reach to the bone But in adult most commonly, they involve vertebrae They involve vertebrae Right Am i clear? So what did we discuss? What is the hematogenous spread of infection to the bones? It is more common in the children but it can occur in the adults also Right Where organisms from a distant source sometimes from very minor focus of infection minor skin infections like weil's, freckles or paronychia inflammation related with the nail bed or tonsillitis or some infection in the lungs, genitourinary system Right or from gastrointestinal system Right Bacteria may enter into blood streams Right And if bacteria are moving in the blood But not proliferating We call this condition bacteremia. What we call it ? Bacteremia So from any focus of infection in the body bacteremia can occur And sometimes even from small mucosal breaches like very hard defecation and constipation or sometimes you are chewing very hard food that damages the gum or mucosal buccal mucosa So even some minor mucosal injuries can produce the breaches or cracks through which the bateria can enter into blood stream Bacteremia is a very common phenomena Right Normally what happen when bacteria enter into blood flow reticuloendothelial system phagocytose and eleiminate these bacteria But if due to any reason If bacteria survive in the blood Then they love to settle in certain areas in the body In case of bones of growing children, bactera love to settle in metaphysis And, in adults, they love to settle in vertebral bodies Am i clear? Any question up to this? Then Route of entry
one is haematogenous
other is direct extension Extension from neighboring soft tissues infections From neighboring soft tissues infections For example, If someone has, let me give you an example If I have some soft tissue infection in this area Right Initially maybe that's staphylococcal infection or abscess is limited in the soft tissue But if it is not treated well maybe one day it damages the periosteum which is usually resistant to the bacteria, protect the bond, But if periosteal breachs there due to some neighboring infection then Infective organism can enter into bone Right Classical example of this is ulcer in diabetic foot It is the typical and classical example What is that? Diabetic foot diabetic foot ulcer let me tell you What's wrong with diabetic foot? The patient who have diabetes Right They develop vascular disease as well as they develop damage to the nerves neuropathy Right For example, If a patient who has severe uncontrolled diabetes and he develops atherosclerosis in lower limb vessels Then naturally the vessels will become narrow and blood flow to the foot will be increased or decreased? It will be decreased Right And this decrease blood flow will produce ischemia of the foot And you know when an organ is ischemic Right Can it defend itself against the microbes? No This is one problem and diabetic patients Right There maybe ischemia to the foot Number two Diabetes also damages the nerves Sensory nerves, motor nerves even autonomic nerves And if there is diabetic neuropathy In the lower limb It may result into loss of pain sensations Right And if there is loss of sensation in the foot patient will inadvertently and repeatedly damages foot And patient may not be aware of that kind of damage patient may not be aware that there has been injury to the foot And he will not take care of that and infection will easily settle So if there is ischemia At the top there is neuropathy And both will predispose the foot to more infection At the top in diabetic patient Wbcs or leukocytes white blood cells are not very effective In phagocytosis of orgnisms And intracellular killing of organisms So what is happening? Foot is insensitive Right Getting more injured, more breach of the skin Right more entry of the organisms At the top due to ischemia less blood flow going to the foot Right So less antibodies and less white blood cells are going there That further increasing the chances of infection and then more problem whatever leukocyte reach there whatever leukocyte reach there They are drunk with the high sugar level They are disfunctional leukocyte And they are unable to clear the infection So what really happens and many more problems so in diabetic foot Repeated injury and infection to the foot lead to ulcerations ulceration mean a necrotic part of the skin sloughs off And when there is foot ulcer Right What will happen microbes will go enter into that ulcer And if that ulcer become deep These microbes will reach to the bones of the foot And may produce osteomyelitis So this is a classical example of what kind of osteomyelitis Direct extension from the neighboring soft tissue infection so in ischemic limbs and in diabetic foot Right You can get osteomyelitis Am i clear ? Then third war Bacteria directly pointed into bone microbes are somehow directly planted into bone They are directly inoculated They are inoculating in the bone direct inoculation Direction implantation of or plantation of what we can say of microbes into bone What could be the example? very simple penetrating injury There is blood injury of course skin is compromised soft tissue is compromised And if that has injured the periosteum organisms from the skin may enter in Is that right? So direct plantation it may be penetrating injuries pene-trating-injuries Then there can be surgery During surgery, especially when you are doing When you are doing orthopedic implants Right When you are putting orthopedic implants in the bones maybe unfortunately you plant the bacteria also there Right Then compound or open fractures If someone unfortunately get severe trauma in accident or some other condition and there is fracture of bones and hematoma of the fracture directly communicate with the skin and external world we say these are open fractures of course then bacteria can directly reach there so what did we learn up to now? we learn osteomyelitis is inflammation of bone and bone marrow but it is almost always due to infective organism It may be pyogenic or non pyogenic Most common cause for pyogenic is staph aureus And most common for non pyogenic is mycobacterium tuberculosis And if mycobacterium tuberculosis is damaging the spine then it is called pott's disease then we talk that how these organisms reach to bone and produce osteomyelitis It is very important to know because number one bones are covered by skin and soft tissues number two specifically bones are covered by periosteum and they offer resistance for the osteomyelitis so due to any how the organisms reach there one is organism enter into blood produce bacteremia and blood vessels which are going to the bone, orgnaism reaches through that haematogenous spread second is direct extension from nearby soft tissue infections and third is direct inoculation or plantation of microbes in the bone marrow Here i will again ask if there is haematogenous spread in growing children what is the short bones are involved? Long bones are involved or irregular bones are involved or flat bones are involved? Long bones very good Which part of the long bones? Metaphysis very good And in adult, the most common site is haematogenous spread vertebrae Any question? No Yes Ok he's saying how do the bacteria destroy periosteum? Bacteria destroy the periosteum the way bacteria destroy many other tissues Right very simple that they produce normally bacteria for example staphylococcus aureus They are producing highly damaging enzymes this is one thing secondly when damaging enzyme is there Initially if bacteria is outside the periosteum surrounding soft tissues damage inflammation occur neutrophils come and other macrophages come they also porduce what Destructive enzymes oxygen free radicals All of them not only damage the bacteria or white cells If all this is happening in the vicinity or in the neighborhood of periosteum or for very long time there is every chance they may damage the periosteum Is that right? Periosteum is relatively resistant but not absolutely resistant to bacterial damage Am I clear?
