Osteonecrosis & Infection Flashcards
(110 cards)
1
Q
How does heterotrophic calcification appear?
A
Irregular, splotchy, and amorphous
2
Q
What are the two types of heterotrophic calcification?
A
- Metastatic
- Dystrophic
3
Q
heterotrophic calcification
What are some examples of metastatic calcification?
A
- Hypercalcemia
- Hyperphosphatemia
4
Q
heterotrophic calcification
What are some examples of dystrophic calcification?
A
Occurs locally in diseased/damaged tissues ie. trauma, degenerative diseases, tumors
5
Q
What is reactive bone formation?
A
Intramembranous bone formed in response to stress on bone or soft tissue
6
Q
How does reactive bone formation work?
A
Stimulus lifts the periosteum resulting in intramembranous bone formation
7
Q
What types of bone exhibit reactive bone formation?
A
Woven or lamellar (cortical, trabecular)
8
Q
What are the types of periosteal reactions?
A
- Solid
- Laminated
- Spiculated
- Codman’s triangle
9
Q
Besides periosteum, reactive bone formation can involve ___
A
endosteum
10
Q
What is a solid periosteal reaction?
A
The periosteum is lifted slowly and fills in completely
Slow growing, typically non-aggressive
11
Q
What are some causes of solid periosteal reaction?
A
- Bone hemorrhage ie. fatigue fractures
- Benign bone tumors ie. osteoid osteoma
12
Q
What is a laminated periosteal reaction?
A
Aggressive process where periosteum is lifted, stops, lifts again, and so on; bone is laid down during the rest phase
13
Q
What is a spiculated periosteal reaction?
A
Aggressive process where periosteum is lifted rapidly and bone grows along the Sharpey fibers
14
Q
How does spiculated periosteal reaction appear in radiographs?
A
“Hair on end” or “sunburst” appearance
15
Q
What is Codman’s triangle?
A
Aggressive process extending beyond bone rapidly; periosteum is stripped from adjacent uninvolved bone
16
Q
What is osteonecrosis?
A
Death of bone and bone marrow in the absence of infection
17
Q
What is the general cause of osteonecrosis?
What are some specific examples?
A
Loss of blood supply:
- Arterial rupture (trauma)
- Arterial compression (myoproliferative disorders)
- Arterial blockage (thromboembolic events)
18
Q
How does osteonecrosis change name based on location?
A
- Epiphyseal: avascular necrosis
- Metaphyseal/diaphyseal: bone infarct
19
Q
How is osteonecrosis histologically characterized?
A
Lack of cells: empty lacunae, dystrophic calcifications
20
Q
How does osteonecrosis present radiographically?
A
- Necrotic zone may appear radio-opaque
- Radiolucent area surrounds necrotic bone
21
Q
What is the acronym for osteonecrosis etiology?
A
PLASTIC RAGS:
Pancreatitis, pregnancy
Lupus
Alcoholism
Steroids (corticosteroids)
Trauma
Idiopathic, infection
Caison disease, collagen vascular diseases, Cushing disease
Rheumatoid arthritis, radiation therapy
Amyloidosis
Gaucher disease
Sickle cell disease / thalassemia
22
Q
What is osteomyelitis?
A
Inflammation of bone due to bacterial infection
23
Q
60-80% of osteomyelitis is caused by which bacteria?
A
Staphylococcus aureus
24
Q
What are two types of osteomyelitis?
A
- Acute pyogenic osteomyelitis
- Chronic osteomyelitis
25
What are the routes of spread of osteomyelitis?
1. Hematogenous (blood)
2. Direct inoculation (after open fracture)
3. Direct spread from nearby infection
26
In the case of hematogenous osteomyelitis, bacteria spread from inside the bone to the subperiosteal space using the ___ and ___ canal systems
Haversian and Volkmann canal systems
27
The level and rate of tissue destruction or aggressiveness of osteomyelitis depends upon:
* **Virulence of the bacteria**
* Age of the patient
* Overall health of the patient
28
Who are high risk patients for osteomyelitis?
* Children
* Elderly
* Diabetics
* Immunocompromised
* IV drug abusers
* Homeless
* Post-surgical patients
29
What are some sources of hematogenous dissemination of osteomyelitis?
* Skin
* Dental sources
* Contaminated needles
* Other sites of infection
30
Which regions of bone are frequently affected by osteomyelitis?
Metaphyseal regions especially of lower extremity
31
What age group of patients most commonly presents with osteomyelitis?
Children 5-15 years of age
32
What is the nature of inflammation for acute pyogenic osteomyelitis?
Aggressive, virulent bacteria lift the periosteum and go through it to invade neighboring tissue relatively quickly
33
What is the nature of inflammation for chronic osteomyelitis?
Less virulent, will often lift periosteum, causing reactive bone formation
Can continue for years; may also progress through the periosteum after a long period of infection
34
#osteomyelitis
What happens when bacteria escape the vasculature and proliferate to bone?
* Bacteria lyse osteocytes
* Localized tissue necrosis
* Localized bone marrow edema
35
#osteomyelitis
What is the result of bone marrow edema?
Increased medullary pressure due to mechanical compression of capillaries
36
How do osteoclasts act in response to osteomyelitis?
Activity increases in the area of the infection:
* Local osteolysis
* Regional osteopenia
37
#osteomyelitis
What happens if bacteria break through the cortex into subperiosteal space and do not go through the periosteum?
* Necrotic debris creates localized pressure
* Lifts the periosteum, initiating reactive bone formation
38
#osteomyelitis
What is periostitis?
Inflammation of the periosteum
39
#osteomyelitis
Periostitis and increased pressure cause ___ contributing to ___
loss of blood supply to cortical bone contributing to necrosis
40
#osteomyelitis
If the bacterial infection penetrates the periosteum, what may eventually be affected?
May penetrate joints, soft tissues, and skin
41
#osteomyelitis
What is a sequestrum?
A piece of devascularized bone becomes separated from the remainder of the bone due to chronic osteomyelitis
42
#osteomyelitis
What is an involucrum?
A layer of new bone growth outside existing sequestrum
43
#osteomyelitis
What is a cloaca?
A gap in the cortex of a bone that allows the drainage of pus or other material from the bone into the adjacent tissues (due to chronic osteomyelitis)
44
#osteomyelitis
What is a sinus?
Forms from the infected bone to the skin surface, draining pus through its tract
45
What are some ways reactive bone formation, due to chronic osteomyelitis, may change the architecture of the bone over time?
* Enlargement
* Sequestrum
* Involucrum
46
What are some physical characteristics of chronic osteomyelitis?
* Reactive bone formation changing architecture
* Cloaca and possibly sinus
* Multiple lytic lesions in bone, may result in porous appearance
* Can destroy multiple bones and multiple tissues over time
47
If multiple bones and multiple tissues are involved, ___ must be on your differential diagnosis until proven otherwise
infection
48
Osteomyelitis (acute pyogenic) presents with which cardinal signs?
* Rubor (redness)
* Dolor (throbbing pain worsening rapidly)
* Calor (rapid onset/increasing high fever)
* Tumor (swelling)
49
___% of bone infections become chronic
10%
50
What is a Marjolin ulcer?
Squamous cell carcinoma (rare) of the bone (infection)
51
When are changes in bone due to infection radiographically visible in the extremities?
What about in the spine?
Extremities: 7-10 days
Spine: 21 days
52
What are some radiographic findings in osteomyelitis?
* Loss of cortical definition
* Loss of trabecular patterning
* Aggressive periosteal reaction
53
What is spondylodiscitis?
Vertebral osteomyelitis
54
What are some risk factors for spondylodiscitis?
* Hematogenous spread from other sites
* Intravenous drug use
* Upper urinary tract infections
* Urological procedures
* Discitis
55
What are three possible consequences of spondylodiscitis?
1. Vertebral collapse and paravertebral abscess
2. Spinal epidural abscesses with cord compression by abscess or displaced fragments of infected bone
3. Compression fractures of vertebral body
56
Spondylodiscitis can lead to compression fractures of vertebral bodies
What would be a consequence of this?
Neurological deficits
57
Where does spondylodiscitis tend to occur?
Thoraco-lumbar region, but can be anywhere
58
What are the radiographic characteristics of spondylodiscitis?
* Decreased/obliterated disc space
* Loss of vertebral endplates
59
What are some possible laboratory findings in spondylodiscitis?
* Leukocytosis
* Elevated ESR
* Increased C-reactive protein
* Blood culture
60
How might acute infections of spondylodiscitis be treated?
* IV antibiotics, usually for at least 6 weeks
* Possible surgery to drain and decompress infected area/abscesses
61
How might chronic or more severe infections of spondylodiscitis be treated?
* More surgical intervention for debridement of necrotic bone and drainage of abscesses
* Amputation
* Life long or symptomatic antibiotic regimens
(very difficult to treat)
62
What is a Brodie abscess?
Where are they generally seen/often found?
Subacute metaphyseal infection of bone
Generally seen in children, often found in tibia, femur, fibula, radius
63
How does bone react to a Brodie abscess?
* Osteolytic lesion gets walled off
* Reactive bone from periosteum and endosteum forms around lesion
* May result in sterilization of the lesion
64
What is the etiology of tuberculosis?
Mycobacterium tuberculosis
65
Where does tuberculosis of bone originate from?
Infection in other areas:
* Lungs or lymph nodes
* Bovid strain infection may originate in the guts or tonsils
66
How does tuberculosis spread from other areas of the body to bone?
Hematogenous spread; rarely, direct seeding or implantation
67
Which age group is usually affected by tuberculosis?
Individuals 1-30 years of age
68
Which bones are most affected by tuberculosis?
The spine: tuberculosis spondylitis / Pott disease (lungs to spine)
69
What is the pattern and morphology of inflammation associated with tuberculosis infection?
Chronic granulomatous inflammation
70
What pattern of necrosis is associated with tuberculosis infection?
Caseous necrosis
71
In tuberculosis, what happens with the mycobacterium that allows it to spread?
Mycobacterium exit the vasculature
72
Which feature of tuberculosis produces caseous necrosis?
Granulomas
73
In tuberculosis, caseous necrosis leads to gradual resorption of ___
bony trabeculae
74
With tuberculosis, what reactive bone formation occurs?
Little to no reactive bone formation
75
What happens if tuberculosis infection ruptures into soft tissues?
Cold abscesses (abscesses lacking acute inflammation) occur in spinal ligaments
76
How does resorption of bony trabeculae involved in tuberculosis affect the spine?
* Bone is destroyed
* Weakened vertebral bone collapses under continued mechanical stress (pronounced collapse)
* Rupture and extrusion of the intervertebral disc
77
Can mycobacterium of tuberculosis invade intervertebral discs directly?
No
78
Describe the clinical onset of tuberculosis
Insidious onset: initial pain is usually mild, comes with stiffness
79
How does tuberculosis present upon static and motion palpation?
Focal tenderness, decreased ROM
80
Does spinal pain due to tuberculosis have neurological involvement?
May or may not
81
What is an example of a cold abscess found in patients with tuberculosis?
Psoas abscess
82
What is Gibbus deformity?
Sharply angled kyphosis in thoracic spine due to vertebral collapse as a result of tuberculosis
83
How might tuberculosis lead to paraplegia?
Results from vascular insufficiency of spinal nerves
84
What is the trend of reported syphilis infections?
All syphilis types increasing over time, a reemerging public health concern
85
What is the etiology of syphilis?
Treponema pallidum
86
What are the two types of syphilis?
* Acquired
* Congenital
87
How is acquired syphilis transmitted?
STD/venereal
88
How is congenital syphilis transmitted?
Transplacental contraction
89
When does bone involvement occur in syphilis?
2-5 years after exposure
90
What portion of syphilis patients will develop bone lesions?
<10%
91
Which bones are most commonly impacted by syphilis?
Tibia, nose, palate, skull
92
What are saber shins?
Anterior bowing of the shins due to congenital syphilis or rickets
93
Why do syphilis patients present with saber shins?
Periostitis leads to reactive bone formation
94
What sort of osseous necrosis can occur in patients with syphilis?
* Lysis and collapse of nasal and palatal bones
* Saddle nose: destruction and eventually collapse of nasal septum
95
Where are gummas most common?
Skin, bones, and joints
96
What are gummas?
Granulomatous lesions with central area of coagulative necrosis, epithelioid macrophages, and giant cells surrounded by fibrous tissue
97
Bone adjacent gummas is gradually replaced by ___
fibrous marrow
98
How is the cortex of the bone affected by gummas?
Cortex is perforated
99
How does bone with gummas eventually appear?
Surface shows thickened periosteal response and perforated, ulcerations with wavy margins
100
Congenital syphilis involves the same lesions as adult infection
What are they?
* Saddle nose
* Saber shin
* Gummas
* Bone erosion and destruction
* Neurological symptoms
101
What are Hutchinson teeth?
Altered dental development associated with congenital syphilis; teeth have grooves along their edges
102
How does bone respond to congenital syphilis spirochetes lodging into growth plates?
* Vascularized tissues under the growth plate are destroyed and replaced by granulation tissue
* Bone formation and remodeling are decreased or absent
103
How do growth plate infections due to congenital syphilis appear on radiographs?
A widened growth plate or broad radiolucent metaphyseal bands
104
What is pseudoparalysis of Parrot?
Dislocated epiphysis, functionless limb associated with congenital syphilis
105
With congenital syphilis, the medullary cavity is filled with ___ replacing normal marrow
lymphocytes, plasma cells, and spirochetes
106
With congenital syphilis, as bones grow, they become ___
shortened and deformed
107
With congenital syphilis, a periosteal reaction stimulates ___
thickening cortex
108
New bone formation that forms a sheath around an area of necrotic bone is called ___
involucrum
109
A hyperkyphosis in the thoracolumbar spine due to tuberculosis infection may also be called ___
Gibbus deformity
110
What clinical presentation is specific to congenital syphilis?
Hutchinson teeth
