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BSAVA MSK > Ch 9 Long Bones - Mature > Flashcards

Ch 9 Long Bones - Mature Flashcards

1
Q

Grids during limb radiography are not necessary in…

A

Small dogs <10kg and cats

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2
Q

At what age do the growth plates in the long bones of adult dogs typically close?

A

18 months

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2
Q

Is the diaphysis here overexposed, underexposed, or just right?

A

It is underexposed, owing to the thigh muscles attenuating the beam. These (image) are the correct settings for bone, where both ST and bone detail are good throughout, and the fabellae are clearly visible.

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3
Q

At what age do the growth plates in the long bones of adult dogs typically close?

A

By 18 months

In neutered cats, physes may close later - up to 2-3 years of age

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3
Q

What are Mach lines?

A

Unusual lines / artefacts caused by the OVERLAP of boney structures. They can be radiopaque or radiolucent.

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4
Q

In cats neutered at a young age, how long may the growth plates remain open?
a) Up to 12 months
b) Up to 18 months
c) Up to 2–3 years
d) Throughout their lifetime

A

c) Up to 2–3 years

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4
Q

What is the typical orientation of nutrient foramina and vascular channels in the diaphyses of long bones in dogs?

A

caudoproximal to craniodistal

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5
Q
A

physeal scar of distal radius in 14mo lab

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6
Q
A

black arrow: supratrochlear foramen
white arrowheads: lateral supracondylar crest
white arrow: medial epicondyle
black arrowhead: lateral epicondyle

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7
Q
A

arrow deltoid tuberosity
arrowhead teres major attachment

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8
Q
A

black arrow, white arrow nutrient foramen
white arrowhead Mach line

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8
Q

what is this line?

A

tricipital line - origin of the **lateral head of the triceps **muscle (also greater tubercle)…inserts on the olecranon.

NB The long head of triceps originates at the distolateral scapula and infraglenoid tubercle

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8
Q

Where is the deltoid tuberosity located on the humerus?

A

On the lateral aspect of the proximal third of the diaphysis

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8
Q

What structure is sometimes profiled medially on the proximal humerus?

A

Attachment of the teres major muscle

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8
Q

The humeral condyle is composed of the medial _______ and lateral___________.

A

(medial) trochlea
(lateral) capitulum

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9
Q

By what age does the ossification of the medial trochlea and lateral capitulum of the numerus typically close?

A

by 3 months

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9
Q
A

The arrows indicate the prominent supracondylar foramen in cats.

On the CrCd view the anconeal process engages the supratrochlear fossa. There is no supratrochlear foramen in cats.

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9
Q
A

radius and ulna of a dog
with the normal lateral styloid process of the distal ulna identified (arrowed).
The distomedial aspect of the radius has an oblique distal eminence, forming the medial styloid process.

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9
Q

cat or dog

A

cat; normal feline radius and ulna.
The lateral styloid process is indicated by the arrows. The square-shaped olecranon is indicated by an arrowhead.

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10
Q

which has (greater and lesser) tubercles - humerus or femur?

A

Humerus (the femur has trochanters)

between the humeral tubercles = bicipital groove

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10
Q

Which bone has a single condyle?

A

Humerus - the condyle is made of the medial trochlea and the lateral capitulum.
The femur has 2 condyles, inbetween which is the intercondylar fossa

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10
Q

Which of these do not exist in the cat humerus?
A) supracondylar foramen
B) supratrochlear fossa

A

B) supratrochlear fossa

The supracondylar foramen is actually large/prominent in cats.

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10
Q
A

trochanteric fossa between lateral greater trochanter and medial lesser trochanter

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11
Q
A

black arrow - gastrocnemius attachment (usually seen in older animals)
white arrow - lines caused by intercondylar fossa (proximally)
arrowhead - extensor fossa

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11
Q

The extensor fossa is on the lateral or medial condyle of the femur?

A

lateral condyle

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12
Q

How many sesamoid bones are at the distal femur?

A

3
1 patella
2 fabellae

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12
Q

Which variation of fabellae are sometimes observed in dogs? in cats?

A

Variations are usually bilaterally symmetrical.
Fabellae can be multipartite/bipartite. In Westies, they can be displaced.
In both cats and dogs, they can have 2 fabella of different sizes.

Some cats only have one fabella.

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12
Q
A

single fabella in a cat (normal variation)

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12
Q

How many sesamoids are associated with the tibia? Where is it?

A

1 - popliteal sesamoid, in the slightly lateral aspect of the caudoproximal tibia

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12
Q

what is this and what is the significance?

A

Normal variant, possibly retained hyaline cartilage. In small-breed dogs, may be associated with MPL.

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12
Q
A

arrow - fabellae
arrowhead - popliteal sesamoid

normal locations in a dog

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12
Q
A

The medial fabella is displaced distally. This sometimes occurs in Westies as a bilateral and incidental finding.

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12
Q
A

Fabellae of different sizes. Usually bilateral, incidental.

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12
Q
A

Multipartite lateral fabella, bilateral incidental.
There is also a MPL.

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13
Q
A

2y Greyhound with stress fracture indicated by scintigraphy as the focal area of increased uptake of 99mTc in the distal tibial diaphysis .

13
Q

What are the most common sites of osteomyelitis?

A

long bones and vertebrae (discospondylitis)

13
Q

Where in the long bone does osteomyelitis typically occur in a immature dog vs. mature dog?

A

immature - metaphysis

mature - diaphysis

13
Q

Why would a diaphyseal fracture occur secondary to osteomyelitis?

A

Because in adult dogs, osteomyelitis of the long bones spreads via the nutrient foramen.

13
Q

Chronologically, what are the radiographic findings of hematogenous osteomyelitis?

A

Initially there is a soft tissue swelling.
2-3 weeks later, there is new bone formation.
Pathological fractures can occur.

13
Q

Which 3 fungals are common causes of hematogenous osteomyelitis, and where is their geographical distribution?

A

Coccidiomycosis - SW USA, Mexico, Central/South America

Blastomycosis - SE USA

Histoplasmosis - Central USA

Also, Aspergillosis can also affect long bones.
Additionally, saprophytic fungals have been reported secondary to chemotherapy.

13
Q

Which protozoal disease causes peroisteal reactions?
Which protozoal disease cause a mix of osteoproliferative and osteolytic changes?

A

Hepatozoonosis causes polyostotic aggressive bone lesions affecting the perisoteum.

Leishmania causes of a pattern of periosteal and intramedullary osseous proliferation, involving the diaphysis at the nutrient foramen.

14
Q

How is hepatozoonosis trasnsmitted?

A

brown dog tick, Rhipicephalus sanguineus

14
Q

What part of the bone does hepatozoonosis affect and what is its radiographic appearance?

A

Periosteum - ranges from irregular periosteal proliferation to smooth laminar thickening.

15
Q

Which protozoal disease is this likely to be?

A

Leishmania, there is a mixed lytic/proliferative pattern…whereas histoplasmosis usually involves just the periosteum.

15
Q

JRT with history of a dog bite.

A

Moderately aggressive periosteal reaction and soft tissue swelling = osteomyelitis.

16
Q

Cat with a discharging sinus after a cat bite. What is the arrow pointing to?

A

bone sequestrum (radiopaque line surrounded by radiolucency)

16
Q

A dog with a huge (excessive) callous after fracture repair with IM pin. What is the arrow pointing to?

A

bone sequestrum (radiopaque line surrounded by radiolucency)

17
Q

Distribution and clinical signs of a secondary osteomyelitis

A

Usually monostotic, or at least one limb (if polyostotic)
Typical signs: fever, swelling, draining tracts

18
Q

How many days until there are radiographic signs following development of secondary osteomyelitis?

A

7-10 days, then bone lysis or proliferation are apparent

19
Q

In osteomyelitis, what kind of periosteal reaction is present?

A

Often aggressive, extensive; palisading.

20
Q

What does a sequestrum look like?

A

A sequestrum is a bone fragment within a radiolucent cavity (called a cloaca), which is surrounded by a sclerotic or proliferative rim (called the involucrum).
The sequestrum itself is more radiopaque then the surrounding bone.

21
Q

Sequestrum, cloaca, involucrum - what are they?

A

Sequestrum is the bone fragment.
Cloaca is the cavity holding the sequestrum.
Involucrum is the envelope of proliferative bone encasing the cloaca.

22
Q

Radiolucent areas surrounding metal implants can be confusing on a radiograph. They are usually due to either implant motion or infection. Those due to implant motion usually have _____________________.

The radiolucent areas caused by infection ______________

A

(Implant motion radiolucency is usually) uniform width and margins, and may be surrounded by a band of sclerosis

(Infectious radiolucency around the implant) can have an uneven appearance with indistinct bone margins.

23
Q

On digital radiographs, there is an artifact that causes radiolucency around metal implants. What is it called and what causes it? How do you distinguish this from osteomyelitis?

A

Uberschwinger (or rebound) artifact, is created by incorrect processing of the data due to large differences in density between the metal and surrounding bone. It can be differentiated from these because it conforms to the shape of the object, is uniform in width and should be present around other similar compounds.

24
Q

What is metallosis?

A

A build-up and shedding of metal (from permanently-placed implants, e.g. hip replacement) into the soft tissue.

25
Q

What are osteoclastomas?
- what are they also called/categorised as?
- rare or common?
- benign or malignant neoplasia?
- where do they appear?

A

Giant cell tumours are (very) rare, and appear in the epiphyses/metaphyses of long bones, especially the distal ulna.

26
Q

What does an osteoclastoma (giant cell tumour) look like?

A

Multilobulated, septated, expansile lytic mass.
Osteoclasts break down bone, hence osteoclastoma - bone is resorbed rather than produced.

27
Q

Difference between bone cyst and osteoclastoma?

A

Osteoclastoma occurs in old patients, and in the epi/metaphysis.

28
Q

What is an osteochondroma? Which age group ?

A

Solitary, benign lesion. —- OR —- can come in multiples as ‘Multiple Cartilaginous Exostoses’ which is hereditary, so in young animals will be present at the site of endoCHONDRAL ossification, while in adults, persists as bony prominences.
Usually clinically insignificant, but can undergo MALIGNANT TRANSFORMATION into osteoSARCOMA or chondroSARCOMA.

29
Q

2yr boxer with swelling on medial distal radius

A

osteochondroma (image ML view)

30
Q

Name the 3 primary bone neoplasms.

A

Osteosarcoma
Chondrosarcoma
Fibrosarcoma
Hemangiosarcoma

31
Q

Where do osteosarcomas arise from?

A

75% occur in long bones, most arising from the medullary cavity, but some originate from the cortex, the periosteum, or even extraskeletal structures.

32
Q

Where do osteosarcomas readily metastasis?

A

Lungs

33
Q

What are the most common locations for osteosarcomas?

A

Distal radius
Proximal humerus
Distal (or prox.) femur
Proximal (or dist.) tibia

34
Q

What is the age distribution of osteosarcomas?

A

Biphasic, 2 years and 8 years

35
Q

What are the 3 types of surface osteosarcoma, from least malignant to most?

A

parosteal / juxtacortical - arises from the periosteal connective tissue. They are irregular mineralised masses with smooth borders. The cortex is usually intact (at first).

periosteal - extensive ST component with mineralisation, invades the cortex.

high-grade surface osteosarcoma - indistinguishable from a central (the classic) osteosarcoma, except that it’s more peripheral.

36
Q

Which periosteal reaction is classic for osteosarcoma?

A

Sunburst

37
Q

Can osteosarcoma invade adjacent bones or cross a joint?

A

Yes, rarely.

38
Q

The presumptive diag- nosis for an aggressive monostotic metaphyseal lesion should be_____________, although __________________must be considered in _________________.

A

osteosarcoma
fungal osteomyelitis, endemic countries

39
Q

Which breed is at a higher risk for developing chondrosarcomas than other breeds?

A

Golden Retriever

40
Q

Where do chondrosarcomas usually occur?

A

Flat bones: pelvis, scapula, skulla, ribs

14% of chondrosarcomas are reported in long bones.

41
Q

Where and how often (%) do chondrosarcomas metastasise?

A

lymph nodes, then lungs in 20% of cases

42
Q

How do chondrosarcomas compare (radiographically) to osteosarcomas?

A

slower growing
more lytic and expansile, centrally destructive
minimal periosteal reaction

43
Q

What is a predilection site for chondrosarcoma?

A

Proximal tibia

Appendicular chondrosarcoma has been reported to cross a joint.

44
Q
A

osteosarcoma

45
Q
A

unusual location for an osteosarcoma

46
Q

What is the most common polyostotic bone neoplasm?

A

multiple myeloma

47
Q

Multiple myeloma results from a neoplastic proliferation of ______________. This leads to __________________.

A

plasma cells in the bone marrow
osteoclastic activity (bone resorption)

48
Q

What are less common causes (than multiple myeloma) of multifocal bone lysis?

A

lymphoma/sarcoma
polyostotic osteosarcoma (rare)

49
Q

Which breeds are at higher risk for histiocytic sarcoma?

A

Golden Retriever (also chondrosarcoma)
Bernese Mountain Dog
Rottweiler

50
Q

What is a predilection site for histiocytic sarcoma (regarding long bones)?

A

proximal humerus and periarticular sites

In disseminated HS, also the vertebrae and ribs.

51
Q
A

intermuscular lipoma, between semimembranosus and semitendinosus (classic location)

52
Q
A

hemangiosarcoma of distal ulna:
- smooth periosteal reaction (tiny proximal arrow)
- thinned cortex (arrowhead) with disruption (arrow)

primary bone hemangiosarcoma is rare, and may be indistinguishable from other sarcomas.

53
Q

To which long bones and where on them do malignant neoplasms metastasise?

A

humerus and femur, diaphysis at the nutrient foramen

54
Q
A

polyostotic (distal femur, proximal tibia) aggressive bone lesions, metastases from a prostatic adenocarcinoma

55
Q
A

fibrosarcoma, example of malignant transformation

56
Q
A

BSAVA MSK (9 decks)

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