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INFECTION, METABOLIC, ENDOCRINE DISEASES
INFECTIOUS CATEGORY
Infectious bone diseases are the most destructive, even RA, Psoriasis and the other arthritides can’t
compare to the destruction that infections cause to bone and surrounding tissues.
The most common organism seen in bone and joint infections is STAPH (90%)!!!
Classic features of infection include…increased ESR/WBC and crossing over into joint spaces causing
bone and cartilage to be roughened up and destroyed.
4 Categories of Infection:
1. SUPPURATIVE
- Posterchild for this category is Staph!
- The organism producing pathogens and toxins characterizes this category. Organisms take up
space in the bone, replicate and stimulate our immune system to send macrophages to the site
and kill off the organisms…leaving behind pus, blood or bone debris.
2.
NON-SUPPURATIVE
- Tuberculosis is the poster child of this category. No pyogenic material is produced w/ this
category. Main problem w/ this type of infection is the granulation tissue that is left behind.
Our body walls off the organisms in granulation tissue so they can’t spread.
3.
FUNGAL
- This category is not very common but there are predominant fungal types to different
geographic locations in the US/Canada and worldwide.
4.
SYPHILIS
- STD’s, increased use of IV drugs (crack cocaine) and trading sex for drug addictions has
created an outbreak of this form of infectious disease. 90% of births from mothers infected w/
syphilis are also infected (congenital syphilis).
SUPPURATIVE INFECTIONS
(90% of these infections involve the STAPH bacteria)
OSTEOMYELITIS
- This is a general term for infection/irritation of bone. When the causative organism is known,
then a more specific label is used, such as “bacterial osteomyelitis” for staph infection.
- Having a suppressed immune system or direct introduction of organism by IV drug use
through bypassing our protective skin brings about this disease. Newborns are also very
susceptible to infections.
- Most common organism causing osteomyelitis is STAPH
- Most common organism affecting newborns and localizing to the humerus is STREP
- Most common organism having a predilection for “S” joints…spine, SC joints, symphasis
pubis, SI joints…is PSEUDOMONAS
- The way that organisms get into the bone is through the vascular tree (hematogenous
infections). The blood supply through bone is swamp-like and slow. This gives organisms
the time to make camp and replicate w/o worrying about being washed away and before our
immune system sends the troops.
- Primary sites of infections are Lung, Skin, Genitourinary
- Contiguous spread is possible w/ infectious organisms such as spreading of infection in a
UTI.
- Direct implantation of organism is also common. Example…step on nail, gunshot wound,
knife wound…
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Post surgical infections are another big cause of spread. Example…infections after
abdominal surgery. 1-3 out of 100 surgeries become infected and exhibit osteomyelitis.
Orthopedic surgeries are also risky for developing infections. Example…a diabetic patient
may not be the best candidate for a new knee b/c they are already immune compromised.
Bone infections do not spread via lymph system. They choose the hematologic route b/c of
the slow flow described earlier.
Kids are the most vulnerable to bone infections b/c their immune strength to body size ratio is
much smaller than an adult and the WBC in a younger person is also much lower.
Signs and Symptoms:
o Onset in an adult is insidious, meaning that they are unsure of the onset and they
usually don’t put much merit towards they signs and symptoms.
o Onset in a child is rapid. You can put a kid to bed and the next morning he/she
wakes up sick.
o Classic signs and symptoms are elevated ESR and WBC, warmth, redness and
swelling over the site, motion of joints produces little or no pain, localized pain over
the site.
The common age range for the suppurative category is 2-12 years. The metaphysis of long
bones are most often affected. Boys are more commonly affected than girls (3:1). In this age
range, wound penetration is most common cause. In adults, IV drug use is most common
cause.
INFECTION SLIDES
1.
LOBAR PNEUMONIA
- AP chest film shows pneumonia in upper, middle and lower lobes. The costophrenic angle on
left side of chest is darker than that on the other side. The grayer CF angle demonstrates
infection. The grayish haze of the 3 lobes also indicates infection.
2.
LATERAL KNEE VIEW
- This view showed 4 different responses to infection:
 Sequestrum – This is old dead bone in the center of osteomyelitis
 Involucrum – This is a periosteal attempt to surround and wall off the infection
 Brodie’s Abscess – This is successfully walled off suppurative infection
 Cloaca – This is a channel or decompressive sinus that tries to reduce the
compression/pressure inside the bone. Sometimes this sinus makes its way to the
skin surface and the patient will see pus draining out on the skin.
3.
MRI VIEWS
- The views we saw were side-by-side lateral sections of an older woman’s spine. The sections
indicated multiple minor posterior disc bulges. The surgeons decided to take out multiple
laminae to relieve the disc bulges…an infection ensued and the MRI showed a bright white
area behind the spine, which was a build up of pyogenic material. The lady had very minor
symptoms before the laminectomies and now she is experiencing major symptoms!
4.
AP KNEE
- This view was of a patient who was suffering knee pain and the doc took knee films. The xray came back negative for anything pathological. A small grayish zone was seen around
medial condyle and later it was found out that this man had osteomyelitis.
REMEMBER: OSTEOMYELITIS IS A VERY DESTRUCTIVE BONE DISEASE AND YET X-RAY IS THE
LEAST SENSITIVE IMAGING DEVICE TO CORRECTLY PICK UP THESE TYPES OF INFECTION. IT
IS POSSIBLE THAT OSTEOMYELITIS WILL BE MISSED ON PLAIN FILM. IF PATIENT COMPLAINTS
DON’T ADD UP, SUGGEST CT, BONE SCAN OR MRI TO RULE BONE INFECTIONS OUT.
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An easier way to differentiate patient complaints and the possibility of osteomyelitis is to ask the patient to
load the joints around the painful area. Loading the joints or bones causes pain while passively moving the
bones or joints will cause no pain.
5.
DISCITIS
- Different x-ray views demonstrated many features of discitis
- Paravertebral Tissue Widening – along the lateral sides of the vertebral column we saw
widening of the soft tissues. This is due to pus (infection), blood (trauma) or cells (tumor).
We also noted that the Battson’s Plexus maybe involved. This plexus is a bunch of valveless
veins that drain this area and is often involved in soft tissue swelling.
- Discitis from Septic Arthritis – lateral view of spine demonstrates concavities of the
endplates adjacent to the discs. This was due to the NP being jammed up and down into
them. Basically the endplates are destroyed and deformed. When both sides of a joint are
involved…think ARTHRITIDE!
- Pubic Symphasis Destruction – The destruction of this disc and surrounding bone was
caused by a UTI that traveled to the pubic bones. Now the symphasis pubis is an unstable
joint and this makes the entire pelvis hypermobile.
6.
AP SHOULDER
- This view demonstrates metaphyseal/diaphyseal infection of the sharpey fibers of the rotator
cuff muscles.
- We see what is called Permeative Destruction Pattern. This is an unorganized trabecular
pattern of internal bone. Has a blotchy look to the head and shaft of humerus. Infections
cause insidious symptoms whereas tumors will manifest pain symptoms over weeks to
months. Though tumors and infections are the most aggressive bone destroyers, infections are
by far the most aggressive.
- Another view of a shoulder demonstrates black specks along the acromion w/in a soft tissue
swelling. These specks are gaseous areas caused by Clostridium infection.
INFECTIONS IN CHILDREN
These infections like to target the metaphysis of long bones and joint capsules such as the hip, knee,
shoulder joints…
The organism replicates in the metaphysis and takes up space. The immune response is to drain and fight
the organism in this area, which further decreases space w/in the bone. Eventually ischemia in this area
will occur b/c blood vessels are squeezed off from pus, blood and cells that are accumulating. This now
leads to an increase in the intramedullary pressure. When child loads the bone or joint, it causes pain. We
saw bone scans of a child w/ a suspected bone infection and the results were one leg appeared darker than
the other. The darker leg is the problem leg…there is increased osteoblastic activity in this leg. A soft
tissue film was taken of the leg below the knee and we saw the increased swelling of surrounding tissue
around both the tibia and fibula.
Next we saw a foot film w/ emphasis on the toes. What we were looking at was Neurotropic Joint Disease
and Infection. This appeared as a candy lick appearance at the distal phalanges and destruction of the 4th
and 5th rays (metatarsals).
7.
BRODIE’S ABSCESS
- This is a successfully walled off suppurative infection as described before.
- We saw this in an AP ankle view and it looked like a grayish spot on medial malleolus.
- Classic manifestation would be…patient stresses the joint w/ activity and pain reduces w/ rest.
This sounds like a stress fracture. Then the patient mentions that the pain is worse at night, it
wakes them up and aspirin reduces the pain. These last 2 bits of info should clue us in that
there is something more than stress fracture going on. When the patient tells us about these
symptoms think Brodie’s Abscess or Osteoid Osteoma.
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Osteoid Osteoma – symptoms are the same as a Brodie’s Abscess but the past history of the
patient will more than likely show history of upper respiratory infections or urinary tract
infections.
Doctors usually will go in and scrape this walled infection off of the bone. Antibiotics will
not work b/c they will not get through the walled off shell around the organism.
Bone scans will show hot spots (darker black areas) at site of abscess.
TARGET SIGN
- Saw an AP knee and noticed lightly shaded concentric rings around a darker gray spot on the
proximal tibia. This is the sign of bone infection on MRI.
NON-SUPPURATIVE INFECTIONS
The poster child for this group of infections is Tuberculosis (TB). This always follows a lung infection. TB
will look like white polka dots all clumped together in the lung tissue…called a cold abscess. There are no
active organisms found in these abscesses (these are a result of dystrophic calcification). This infection
will also look bright white on MR. TB organisms are less dense than bone and soft tissue so they will
appear as a lucency on film.
TB is the least destructive infectious disease. In relation to speed, this is not very aggressive. It is slow
progressing, indolent, quicker than bone tumors but much slower than staph infections.
The TB that we are experiencing now is much stronger than the TB of the past. We now have to give 2nd
and sometimes 3rd tier medications to kill the organism whereas in the past, 1 st tier meds were sufficient.
Now that TB is more resistant, the drugs we use to combat the organism are more harmful to the patient.
There is a strong link b/w TB and the urban environment w/ crack cocaine addictions and IV drug use at
the root of the disease.
1.
TB GRANULOMA
- AP chest view demonstrates a bright white circular shape in center of chest and we all thought
it was the heart shadow. Then around this bright white circle there was a dotted line…this
dotted line was the outer border of the heart shadow and the bright white circle was a large
amount of TB granuloma tissue.
2.
ANGULAR KYPHOSIS
- Lateral thoracic view demonstrated a sharp angle to the normal kyphotic curve and we call
this a Gibbus Deformity. This is strongly linked w/ TB.
- Along the anterior margins of the vertebral bodies we saw a large white mass again and then a
less white heart shadow in front of it. In a Gibbus Deformity the most likely place for
granulation tissue is at the acute angle of the deformity.
3.
LONG VERTEBRA
- Lateral view of the spine demonstrates a long vertebra or blocked vertebra. This occurred due
to increased stress on the bone, which led to increased growth and density.
4.
TB DACTYLITIS
- AP view of 2-3 yr. old child’s hands and wrist. Saw only 2 carpal bones and a swollen middle
finger. TB has interrupted some of the cortex around middle finger and parts of the bone are
destroyed along w/ soft tissue swelling.
5.
AP PELVIS
- This view demonstrated a severely dislocated femur. TB destroyed the acetabulum to the
point where the patient put extra stress on hip joint and it caused the femur head to break
through the acetabulum and dislocate into the gluteal muscles. The femur head appeared to
be inside the pelvic bowl.
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SYPHILITIC INFECTIONS
Syphilitic infections are of 2 types…Acquired and Congenital. Acquired syphilis is seen in adults and is a
consequence of poor behavior. Congenital syphilis is passed from infected mother to child.
Less than 10% of acquired syphilis presents w/ bone change.
25% of kids w/ congenital syphilis die in utero.
25 – 30% “
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40% get sick later after birth.
90% of kids born to moms w/ syphilis will themselves have syphilis.
Syphilis targets the vaso vasorum tissue leading to decreased blood supply to vessel walls. Blood vessels
die w/o blood supply.
Congenital syphilis sets up camp beneath the epiphysis and affects bone growth.
Stages of Syphilitic Infections:
- Metaphysitis Stage – In this stage we see a saw-tooth appearance to the metaphysis. Winberger’s
Sign of Syphilis is seen in this stage and it involves medial erosions of tibial metaphysis.
- Periostitis Stage – This stage is marked be periosteal reaction. We see a B/L, symmetrical
periostitis of the long bones.
- Osteitis Stage – If properly treated, syphilis will never reach this stage. If untreated, we will see
increased bony density, recognizable softening of bone, classic sign called “Saber Shin” in the
tibia (anterior bowing of tibia). Will find multiple swollen joints that are not painful called
“Clutton’s Joints”. Squared off, pegged teeth w/ classic notched incisors (Hutchinson’s Teeth) are
also seen in this stage.
We saw an AP view of the leg and it demonstrated the classic Saber Shin. The tibia was bowed out
anteriorly along w/ a ridge of bone forming on medial shaft of tibia.
FUNGAL INFECTIONS
Fungal infections are quite rare, but certain regions of the world have their predominant fungus…
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Histoplasmosis – Seen in the Ohio River Valley, this is a fungus of soft tissue and does not
migrate to bone.
Coccidioidomycosis – Seen in the Southwestern US. Favorite sites of infection are bony
prominences, acromion, medial and lateral maleoli, and patella. All this fungus needs is a blood
supply to the bone to cause damage.
Blastomycosis – Seen along the US and Canadian border. Told a story of a 52 year old woman
who had headaches, dysphasia, fever, night sweats and increased WBC count. There was a
landslide in her area and her house was destroyed. She began feeling these symptoms after going
to the site and trying to salvage anything she could. What happened was spores of Blastomycosis
went airborne during the landslide and she inhaled them. Her cervical x-ray showed a marked
increase in prevertebral soft tissue spaces. Tests for this fungus will include staining of a culture
w/ methionine blue…will be positive when this fungus is present. This stain is exclusive to
blastomycosis.
Maduramycosis – called Madura Foot for short. This is the most prevalent fungus worldwide.
An infection w/ this fungus comes about from direct contact of bare feet w/ an exposed cut or sore
w/ fecal material on the ground or in the mud. Very common in Africa. Don’t walk through shit
in your bare feet!
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Dr. Kuhn then started talking briefly about Polio. He showed us 2 slides. One was of a dog’s thigh and leg
w/ a bright white bulge along the shaft of thigh, and an AP pelvis w/ one ilia and femur appearing
hypoplastic when compared B/L. Polio is another destructive/deforming bone infection.
NEURO, METABOLIC, ENDOCRINE (NME)
This section will cover osteoporosis and osteopenia. These diseases/disorders are the most common bone
disorders in the US.
OSTEOPENIA – Poverty or lack of bone
This bone disorder is characterized by thin cortex and wide medullary cavities (weakened bone w/ loss of
trabeculae). 80-90% of bone diameter is medullary while 5% is cortical.
OSTEOPOROSIS
3 Categories of Osteoporosis:
- Generalized – this category of OP involves all bones of the body! Examples of OP in this
category would be Postmenopausal OP and Hyperparathyroidism.
- Regionalized – this category of OP involves related groups of bones! (bones of the arm, legs,
wrist/hand…) Examples of OP in this category are caused by post-immobilization (slings, casts,
disuse…) and sympathetic overdrive (reflex sympathetic dystrophy and Sudex dystrophy).
- Localized – this category of OP only affects portions of bone! An example of this would be the
Romanus lesion we saw w/ AS. Infections can cause localized OP too. This category of OP is the
most serious b/c the lesions/abnormalities are sometimes so small that they are overlooked. This
fact gives the OP time to spread and cause more damage. Metastasis is correlated w/ localized
OP.
Generalized Osteoporosis will progress through 5 phases…(Refer to Kuhn’s drawings of vertebrae in class)
1ST – we will first notice some loss of vertical trabeculae and sometimes all of the horizontal trabeculae.
This loss of horizontal trabeculae (due to post menopausal factors for example) accentuates the vertical
trabeculae that are left. This is seen throughout all levels of the spine. A hemangioma, for example, will
also cause this pattern of trabecular loss, but this only happens at one or two levels.
2ND – the next phase is a total loss of horizontal and vertical trabeculae.
3RD – Cod Fish Deformity – no trabeculae, concave endplates, and squashed S to I appearance.
4TH – Wedge Fracture – this is seen more often in the thoracic spine, vertebrae appear w/ anterior wedge w/
a chewed out mouth-like area on the anterior of the body. These come about after a Trivial Trauma like
sneezing or stepping off of a curb wrong.
- If posterior dimension of wedge is at least 80% of the level above and below…Simple Wedge
- If posterior dimension of wedge is less than 80% of level above and below…Vertebra Plana
o Vertebra Plana (pancake or silver $ vertebra) is linked w/ malignant processes like
osteomyelitis. There is no trauma associated w/ this.
5TH – Check Sign – This happens due to an abrupt failure of the bone. Appears as a squashed vertebra w/ a
dug out area on superior endplate where bone was stressed beyond limits. This is linked to pathologic
findings such as Lytic Metastasis.
REMEMBER THAT VERTEBRA PLANA AND CHECK SIGN ARE LINKED W/ PATHOLOGIC
DISORDERS.
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OSTEOPOROSIS SLIDES
1.
LATERAL THORACIC VIEWS
- One view demonstrated both the Cod Fish Deformity and the 1 ST phase of osteoporosis w/ the
accentuated vertical trabeculae.
- This view was of a woman w/ postmenopausal disorder.
- Another view demonstrated a dark black shadow along the posterior margins of all the
thoracic vertebrae and a black density in front of the bones, which was lung tissue and should
have been white.
- In another view we saw visible vertical trabecular lines on 4 of the 5 lumbar vertebrae. We
also saw a decreased disc space b/w L5 and sacrum.
2.
RETROPULSION
- This is a result of a fracture or trivial trauma and a simple wedge of a vertebra. The bone
pushes backwards into the central canal and at certain levels this is more serious than at
others. Seen w/ central canal stenosis.
3.
WARD’S TRIANGLE
- We saw a drawing of a femur head w/ 3 orientations of trabeculae. The crossing of these
patterns makes a triangle and the size of the triangle tells us how strong or weak the bone is.
- (1) This group of trabeculae runs from superior FH to inferior FH and inferior neck of femur.
This group is called the Principle Compressive Group. They take on the most weight
bearing through the hip joint. With osteoporosis, this group is the last one affected.
- (2) This group of trabeculae runs from Greater Trochanter to inferior femur neck. This group
is called the Secondary Compressive Group. This area is for muscle attachment and these
muscles pull the FH into acetabulum.
- (3) This group of trabeculae runs from central FH to lateral shaft of femur below GT. This
group is called the Principle Tensile Group. This group deals w/ suspension types of
weight bearing to the lateral cortex of bone.
- Ward’s Triangle is the shape formed by the intersection of these 3 groups and has less
trabecula than the surrounding groups.
- The smaller the triangle…stronger the bone is.
- The larger the triangle…weaker the bone is.
- Missing groups 1-3…bone is even weaker.
ESTIMATING YOUR CHANCES OF DEVELOPING OSTEOPOROSIS:
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Age – over 35…add 25 points
Sex – female…add 25 points
Race – Caucasian or Oriental…add 25 points
Body Type – Small boned or Slender…add 25 points
Family History – Mother, Grandmother, Sisters w/ OP…add 25 points
Additional risk factors include…never been pregnant, experienced menopause, had ovaries removed,
breast-fed your children, are allergic to milk and dairy products, are inactive, have a stressful lifestyle,
consume large amounts of caffeine and alcohol.
Ratings: <85 = low risk 85-170 = moderate risk 170-250 = high risk 250 and up = highest risk
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DIAGNOSING OSTEOPOROSIS
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Plain film is not sufficient for diagnosing OP
SEXA (Single Emission X-ray Absorbtometry) and DEXA (Dual Emission X-ray
Absorbtomety) are 2 of the best ways to get good enough quality to say “yes” or “no” if the
patient has OP. DEXA is the Gold Standard…CT is also a good method to diagnose OP
When doing densometry studies, you can’t compare extremities to overall bone densities b/c
the spine and extremities are totally different.
Hip fractures create a 30% mortality rate due to immobilization and infections
TREATING PATIENTS W/ OSTEOPOROSIS
Recent studies showed that…
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Patients who took Ca++ alone had no change on lone loss
Patients who took Ca++ and Vit. D had slower bone loss
Patients who exercised had a slower bone loss
Patients who exercised, took Ca++ and D showed a stoppage of bone loss
Estrogen therapy alone slowed bone loss
Estrogen therapy w/ Ca++ and D slowed bone loss
Estrogen therapy, Ca++, D and exercise actually added bone
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