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Osteomyelitis – causes, symptoms, diagnosis, treatment, pathology

November 6, 2019

Learning medicine is hard work! Osmosis makes it easy. It takes your lectures and notes to create
a personalized study plan with exclusive videos, practice questions and flashcards, and so
much more. Try it free today! The word ‘osteomyelitis’ can be broken
down. Osteo- refers to bones, –myel stands for
myelo and relates to the bone marrow, and lastly, –itis refers to inflammation. So, osteomyelitis is an inflammation of the
bone or bone marrow, and it typically results from an infection. Normally, if we look at a cross-section of
a bone, we can see that it has a hard-external layer known as the cortical bone and a softer
internal layer of spongy bone that looks like honeycombs. There’s also another layer called the periosteum
that covers the cortical bone – like the lamination of a basketball card – and it’s where the
muscles, tendons, and ligaments are attached. If we zoom into a cross-section of cortical
bone, we can see that it has many pipe-like structures called osteons running through
the length of the bone. Each pipe has an empty center called a Haversian
canal which contains the nerves and blood vessels that supply the osteon. At the outer-border of the osteon is a ring
of cells called osteoblasts which synthesize bone. Along with these cells are osteoclasts that
break down bone. In bones, like the long femur, the tips are
called the epiphysis, while the shaft is called the diaphysis. Between them we have the metaphysis, which
contains the growth plate, the part of the bone that grows during childhood. In osteomyelitis, microorganisms, such as
bacteria, reach the bone to cause an infection in a few different ways. Bacteria particularly affect certain high-risk
individuals like those with a weak immune system, and those with poor blood circulation
due to uncontrolled diabetes. In fact, a major way that bacteria reach the
bone is through the bloodstream, and it’s called hematogenous spread. For example, this might happen in a person
who uses contaminated needles to inject drugs or in individuals undergoing hemodialysis
that may be contaminated by a bacteria or even through the dental extraction of an infected
tooth. Through the bloodstream, the microorganisms
may reach specific places in the body, and this mostly depends on the age of the person. In older adults, for example, the microorganisms
may reach the vertebrae and cause vertebral osteomyelitis. This usually affects two adjacent vertebrae
and the intervertebral disk between them. In children, the metaphysis of long bones
like the femur is commonly affected. The second way that bacteria cause osteomyelitis
is through trauma. For example, in an open fracture after an
accident, the bone may get exposed to the outside environment and come into direct contact
with bacteria. A third way is during surgery when there’s
bacteria that’s introduced into the bone. A fourth way is when an infection spreads
from one area, like cellulitis – which is an infection of the dermis layer of the skin
– to an adjacent area like the bone, and this is known as contiguous spread. There can also be combinations of these. For example, when a prosthetic joint becomes
contaminated with bacteria during surgery and then that bacteria contiguously spread
to nearby bone. Another example, is when people with diabetes
mellitus develop a severe vascular compromise. A small trauma to the foot can lead to the
formation of a foot ulcer, which then becomes infected and spreads to the nearby bone. Now, once the bacteria reach the bone by any
of these routes, they start to proliferate. This alerts nearby immune cells – specifically
dendritic cells and macrophages – that try to fight off the infection. This represents the acute phase of the disease
and occurs over a course of weeks. The immune cells release chemicals and enzymes
that break down bone and cause local destruction. Usually acute osteomyelitis comes to a resolution
– meaning that the immune system eventually destroys all of the invading bacteria. If the lesion is not that extensive, and there’s
viable bone the osteoblasts and the osteoclasts begin to repair the damage over a period of
weeks. However, in some cases, the process turns
into a chronic osteomyelitis – lasting months to years. In that situation, the affected bone sometimes
becomes necrotic and separates from the healthy part of the bone – and that’s called a sequestrum. At the same time, the osteoblasts that originate
from the periosteum may form new bone that wraps the sequestrum in place, this is called
an involucrum. Occasionally, in both acute and chronic osteomyelitis
the inflammation may involve the periosteum. The periosteum is loosely attached to the
compact bone, especially in children, so the two layers can separate and allow an abscess
to form between them. That sort of an abscess tracks along the periosteum,
lifting it up – away from the compact bone. The infection can also spread further to involve
a nearby joint – particularly the knee or hip joint in young children, as well as overlying
muscle, skin, and even get into blood vessels – causing a thrombophlebitis. Many microorganisms cause osteomyelitis, but
the most common is Staphylococcus aureus – a grapefruit looking bacteria that live on the
skin. It can invade the skin and spread contiguously
to the bone, or it can reach the bone through the bloodstream. Another one is Salmonella – a rod-shaped bacteria
that particularly affects individuals with sickle cell disease. Unfortunately, individuals with sickle cell
disease are therefore at risk of getting both Staphylococcus aureus as well as Salmonella
infections. Another pathogen is Pasteurella multocida
– a pill-shaped bacteria. It usually spreads from the skin to the bone
from a bite or scratch from a cat or dog. Now, acute osteomyelitis typically causes
pain at the site of infection as well as fevers. Depending on the location, it may affect use
of the bone. In chronic osteomyelitis, there can be prolonged
fevers and weight loss, due to the chronic inflammatory state. Osteomyelitis is usually diagnosed with using
a complete blood count or CBC which shows an increase in white blood cells, as well
as an elevated erythrocyte sedimentation rate or ESR and C-reactive protein or CRP. These are both non-specific markers of inflammation. Now in addition, sometimes an x-ray is done,
and it might show thickening of the cortical bone and periosteum as well as elevation of
the periosteum. Other findings may include, loss of the normal
architecture of the bone, especially of the trabecular architecture. There’s also osteopenia or loss of bone
mass that becomes evident when more than half of the bone matrix is destroyed. Typically a bone scan or MRI is done to help
confirm the presence of osteomyelitis and to identify a possible abscess. When possible, a bone biopsy is also taken
to help culture and identify the pathogen responsible as well as confirm the diagnosis. Now, treatment typically involves weeks of
antibiotics directed at the organism causing the infection. If there’s an abscess, particularly a vertebral
abscess, causing neural compression or spinal instability, then surgery may also be required. In addition to draining abscesses, surgery
is often needed to remove any necrotic bone – particularly in chronic osteomyelitis where
the sequestrum has to be removed. Alright, as a quick recap, osteomyelitis is
a bone infection. In which the symptoms are inflammation, fever,
and weakness. Staphylococcus aureus is the most common pathogen
responsible for osteomyelitis. And the most common form of infection is through the bloodstream.


  • Reply C A January 9, 2019 at 7:43 pm

    Hi from Peru. Thanks for the videos

  • Reply Mamalaivasan K January 9, 2019 at 7:43 pm

    First like ??

  • Reply Adnan A January 9, 2019 at 7:45 pm

    Thankful to sketchy for grilling the microbes into my mind

  • Reply Dhina Karan January 9, 2019 at 8:05 pm

    Pls upload more

  • Reply Man mansoor1213lrg January 9, 2019 at 8:43 pm

    Super explained wellll

  • Reply Myk | IMystikHD January 9, 2019 at 8:52 pm

    Perfect timing ! Have an exam on orthopedics

  • Reply Salah Akram Bougoffa January 10, 2019 at 12:43 am

    thank you osmosis , i'm a medical student from algeria , and i had osteomyletis when i was 16 yo , i looked all of this years for it , your video is the best explanation that i have so far ? . thank u

  • Reply Islamic Pearls January 10, 2019 at 1:06 am

    Great work ?

  • Reply Ameer Adel January 10, 2019 at 1:20 am

    This is a short information about this important subject, it need more information about pathophysiology , diagnostic criteria,treatment options and complications, but thanks ??

  • Reply Raghad Hazim January 10, 2019 at 4:09 pm

    Thank you so much !!!

  • Reply Phalexan January 10, 2019 at 8:16 pm

    I actually had this as a kid

  • Reply Moni Mone January 11, 2019 at 9:52 am

    As usual, The best work :DD

  • Reply Nitin Dhamala January 11, 2019 at 3:04 pm

    Much needed lecture

  • Reply J Riddle January 14, 2019 at 5:00 pm

    Staphylococcus Aureus = Very angry Memberberries.

  • Reply tuni31 January 19, 2019 at 2:58 pm

    Excellent overview, as always! You guys rule! But, please, never use those "oww" sounds again. They contrast so much with the tone of everything else. x)

  • Reply amr samy January 22, 2019 at 1:40 pm

    يارب الباثولوجي يموت ?

  • Reply Patel Ankita January 22, 2019 at 3:04 pm

    thank….you.. for your.. all vidios…to make..easy..,quick..& over view..of..disease..

  • Reply Omar Anwar January 24, 2019 at 6:54 am

    that dude talks like a news broadcaster lol

    but as always, great video!!

  • Reply Scherry January 26, 2019 at 5:31 am

    Good work .. tnks … specially the Sound effect of "accident " … ??? …

  • Reply Karthik -Sun February 3, 2019 at 2:46 pm

    @ 3.09 i really was scared to death because of that sound.
    Otherwise good presentation..

  • Reply Love Medicine February 9, 2019 at 4:14 pm

    Thank you Osmosis .. that was great ?

  • Reply john D Mwelwa February 14, 2019 at 3:10 pm

    Thank u❤

  • Reply suchitra gupta February 22, 2019 at 6:25 pm

    Lovely explanation.. Thanks

  • Reply Thenmozhi Baskaran February 28, 2019 at 5:41 pm

    Superb clips .its really easy to understand

  • Reply Junmark Panlilio March 2, 2019 at 12:44 pm

    Sirdo you have pathophysio of tb arthritis?

  • Reply David perpetual March 11, 2019 at 3:47 pm

    Please osmosis, am a patient of osteomyelitis, i have taken different antibiotic and am still having pain, please what should i done, to come out of this final.

  • Reply Emanuel Villanueva April 4, 2019 at 1:48 am

    hola buen día no seria mucha molestia subtitular al español o traducirlo si no fuera mucha molestia por favor gracias

  • Reply Indrakamal Yadav April 20, 2019 at 7:16 am

    Great job??

  • Reply Learning Medicine April 26, 2019 at 12:38 pm

    Thank you so much osmosis. You are life saviours ❤❤

  • Reply N S April 29, 2019 at 10:31 pm

    Wow, what a thorough explanation, keep it up! ?

  • Reply mayur patil May 16, 2019 at 1:26 pm

    Please make a video on osteoporosis

  • Reply DeadlyAlcohol June 1, 2019 at 10:16 pm

    Great video,but got a bit scared.
    I broke my ulna 40 days ago /not an open fracture/.
    Two weeks after i got fever and some sort of infection due to orthopedic needle sticking out from my elbow.
    Spending 10 days in hospital with IV antibiotics,now i'm fine.Can this be necessarily osteomyelitis?
    Any answer will be greatly appreciated !!!

  • Reply Radka Jančová June 15, 2019 at 12:52 pm

    Preparing for my finals, thanks for videos like this! It has been really helpful. Thank you so much!

  • Reply debra fisher June 25, 2019 at 9:24 am

    I have had chronic osteomyelitis from the age of 2 and half years old I am 58 years old now and even though it has been dormant for a while I am fully aware it could awaken at any time even more so due to my immune system being lower due to chemo and radio a few years ago,what saddens me the most is the fact that I cannot get my hands on any medical records so do not know what my surgeon had put down as the cause this video did go some way to helping with an explanation but would still like to know how I got the infection in the first place guess I will never know,

  • Reply yogayantra Dominique July 12, 2019 at 11:21 pm

    can the mycobacterium tuberculosis cause osteomyeltis too?
    Thanks a lot for your great videos

  • Reply Drkhaalid geesh August 11, 2019 at 5:23 pm


  • Reply Hafizah Hoshni August 16, 2019 at 7:57 am

    Awesomely informative and perfectly explained! Thank you so much! ?? 16/8/2019

  • Reply Isaiah Karnes August 18, 2019 at 5:01 am

    I had ostiomyalitos in the hip and spent 3 months in the hospital and the doctors couldn't explain how it happened because I had not infection sight so I'm watching this to get answers

  • Reply mukta yeasmin August 25, 2019 at 4:37 pm

    pls banglae dan

  • Reply Farrukh August 25, 2019 at 7:16 pm

    Great ?

  • Reply Talphi Winsor August 27, 2019 at 4:23 pm

    Is osmosis for free

  • Reply darkestdragon September 15, 2019 at 4:58 pm

    Forgot the symptom of: ungodly levels of pain.

  • Reply Arjun dev a September 17, 2019 at 12:51 pm


  • Reply Z. Azzawey September 20, 2019 at 10:42 am

    Think please

  • Reply Rick September 28, 2019 at 10:45 pm

    Is that John Mulaney narrating?

  • Reply Dave P October 19, 2019 at 4:26 am

    Got infected by this in my 2 feet 26 years ago ( i'm 31) No infection and no doctor can tell what cause it , they broke both of my legs trying to replace it but it got worst. Cant walk for almost 2 years . they found what i had after 9 months of research i believe and the infection was stopped a little bit before my hips . I now have to wear foot prothesis for life (500$ can a pair , last for about a year) , my 2
    foot arch were slumped and i have a hollow foot and a flat foot . I cant walk barefoot so no waterpark for me , my two knees doesnt align with my foot . i destroy every pair of shoes in 3 weeks or so . i cant wear skate for more than 15 min . never been able to stand on a snowboard or skiing ( living in canada , that sucks)

    I have a office job so everything's fine but if someone have the same problem with this than i do i'd be very interested to know what you did to calm pain and been able to do normal stuff .
    Thanks .

  • Reply for everything October 20, 2019 at 10:46 pm

    3:09 l am dead ?????..

  • Reply Abdelaziz Ahmed October 31, 2019 at 6:30 pm

    good work guys i am greatful for you

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