Bone Necrosis Flashcards

1
Q

What is Osteochondritis

A

localised necrosis of bone due to underlying ischaemia from a reduction in blood supply - caused by increased repetitive stress (compression or traction).

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2
Q

Age group most commonly affected by osteochondritis

A

children and young adults

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3
Q

Pathophysiology of osteochondritis

A

recurrent impact or traction injuries causes bleeding and oedema in bone, resulting in capillary compression. This leads to necrosis and separation of bone.

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4
Q

Freiburg’s disease

A

Osteochondritis of the 2nd metatarsal head

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5
Q

Kohler’s disease

A

Osteochondritis of the navicular bone

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6
Q

Keinbock’s disease

A

Osteochondritis of the lunate bone

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7
Q

Panner’s disease

A

Osteochondritis of the capitellum of the elbow

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8
Q

Scheuermann’s disease

A

Osteochondritis in the spine causing vertebral compression

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9
Q

Osgood-Schlatter disease

A

Traction osteochondritis at the tibial tubercle where the tendon attaches

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10
Q

Sever’s disease

A

Traction osteochondritis at the calcaneus where the tendon attaches

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11
Q

Osteochondritis dissecans

A

Fragmentation with separation of bone and cartilage within a joint

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12
Q

Sites predisposed to osteochondritis dissecans

A

Lateral part of medial femoral condyle
Anteromedial talar dome
Superomedial femoral head
Humeral capitellum

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13
Q

Presentation of osteochondritis dissecans

A

Pain
Effusions
Locking
Giving way of the weight bearing joint

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14
Q

Tx of compression types of osteochondritis

A

Restriction of activities is usually enough

splintage in the wrist or foot

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15
Q

Tx of traction types of osteochondritis

A

self limiting & settles with rest

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16
Q

Tx of osteochondritis dissecans

A

surgical pinning of fragments

removal of detached fragments

17
Q

Sites most prone to AVN

A
femoral head 
femoral condyles 
head of humerus 
capitellum 
proximal pole of scaphoid 
proximal part of talus
18
Q

Age group most commonly affected by AVN

19
Q

Causes of AVN

A
Alcohol 
Steroid abuse 
Idiopathic 
Secondary to fractures 
Thrombophilia 
Sickle cell disease
Antiphospholipid syndrome 
Caisson's disease
20
Q

Why do alcohol and steroid abuse cause AVN

A

They alter metabolisation of fat - gets into circulatory capillaries and sludges them up and promotes coagulation. Increased fat content in the marrow compresses venous outflow causing stasis.

21
Q

Why does Caisson’s disease cause AVN

A

This is decompression sickness.

Nitrogen gas bubbles form in the circulation after to fast decompression from deep sea diving.

22
Q

AVN appearance on xray

A

patchy sclerosis
subchondral collapse
irregular articular surfaces
secondary OA changes

23
Q

Tx of AVN

A

Depends on stage of disease

Early -
if articular surface has not collapsed,
drilling under fluoroscopy to decompress the bone

Late -
if articular surface has collapsed,
joint replacement

24
Q

What is osteomyelitis

A

infection of the bone including compact and spongy bone, and bone marrow

25
How do the organisms causing osteomyelitis infect bone
Directly - penetrating trauma, surgery Indirectly - haematogenous spread from an infection or bacteraemia at distant site
26
Patients most susceptible to osteomyelitis
Immunocompromised patients with chronic disease elderly young
27
Pathogenesis of osteomyelitis
Once infection is present in the bone, enzymes from leukocytes cause local osteolysis and pus forms which impairs local blood flow
28
What is a sequestrum
A dead fragment of bone which forms in osteomyelitis that usually breaks off
29
What is the consequence of a sequestrum being present in osteomyelitis
It means that antibiotics alone will not cure infection
30
What is an involucrum
New bone formation around the area of necrosis in osteomyelitis
31
What is a Brodie's abcess
A subacute steomyelitis found in children, which presents insidiously and where the bone reacts by walling off the abscess with a thin rim of sclerotic bone
32
Why are children at risk of osteomyelitis
The emtaphyses of lone bones contain abundant tortuous vessels with sluggish flwo that can result in the acucmulation of bacteria, and infection spreads towards the epiphysis
33
Most common bones in adults affected by osteomyelitis
Axial skeleton (spine and pelvis)
34
Most common sources of infection for osteomyelitis in adults
Pulmonary infections (incl TB) Urinary infections Discitis Previous open fracture or internal fixation
35
Most common causative organism for osteomyelitis
Staph. aureus
36
Tx acute osteomyelitis
"best guess" IV Abx (usually high dose fluclox)
37
Tx chronic osteomyelitis
Surgery to access deep bone tissue, remove any sequestrum and excise infected bone
38
Predisposing conditions to osteomyelitis
``` Diabetes mellitus Sickle cell anaemia IVDU Immunosuppression Alcohol ```
39
Ix for osteomyelitis
MRI