CH 11 Joints

Question 1

Why are sesamoids sometimes not seen on radiographs?

Answer 1

They may not be mineralised.

They start out as cartilage and then (most of the time) ossify, becoming radiographically visible.

Question 2

Absence of mineralization of the medial fabella and popliteal sesamoid is more prevalent in _________ cats than in ________ cats (Arnbjerg and Heje, 1993).

fill in the blanks with either: domestic or pedigree

Answer 2

Absence of mineralization of the medial fabella and popliteal sesamoid is more prevalent in domestic cats than in pedigree cats (Arnbjerg and Heje, 1993).

Question 3

Mineralization of the supinator sesamoid is reportedly present in ___% of cats (Wood et al., 1995) and ___% of dogs (Wood et al., 1985).

Answer 3

40 (cats)
30 (dogs)

Question 4

Which sesamoid does the elbow have?

Answer 4

Sesamoid in the tendon of origin of the supinator muscle

Question 5

Which sesamoid does the carpus have?

Answer 5

Sesamoid in the tendon of origin of the abductor pollicis longus muscle

Question 6

Which sesamoids does the stifle have?

Answer 6

Patella - tendon of insertion of quadriceps muscle
Fabellae - lateral and medial origin of gastrocnemius muscle
Popliteal - tendon of popliteus muscle

Question 7

Which sesamoids does the stifle have?

Answer 7

Lateral plantar tarsometatarsal
Intra-articular tarsometatarsal

Question 8

Which sesamoids do the metacarpo-/ metatarsophalangeal joints have?

Answer 8

Paired palmar/plantar sesamoid bones (tendons of insertion of the interosseous muscles)
Single dorsal sesamoid
(in the extensor tendons)

Question 9

In which stage of arthroses is scintigraphy particularly useful - early or late?

Answer 9

early, when only soft tissue inflammation is present.

Question 10

Answer 10

a) normal
b) reduced joint space (between femoral head and cranial acetabular margin)
c) increased joint space (it’s V-shaped); incongruent joint

Question 11

3 causes of reduced joint width

Answer 11

artifact (beam not centred properly)
cartilage attrition
muscle contracture

Question 12

What is the theory behind vacuum phenomenon?

Answer 12

Nitrogen diffuses from extracellular fluid into the joint space, when there is negative pressure (either naturally e.g. IVDD, shoulder OCD, or induced e.g. traction during stress radiography)

Question 13

What is the initiating factor for osteochondrosis?

Answer 13

Local ischaemia > failure of the the cartilage to mineralise

Question 14

Which joint(s) is(are) more commonly affected by congenital luxation?

Answer 14

Shoulder and elbow

Question 15

manually compressed and distracted coxofemoral joint - is this a normal amount?

Answer 15

No, this is excessive, and indicates joint laxity and poor joint congruity.

Question 16

Cartilage cells have reduced proliferation and differentiation with which vitamin imbalance?

Answer 16

Hypervitaminosis A

Question 17

What is the radiographic lag time of hypervitaminosis A following the start of the inciting cause?

Answer 17

10 weeks

Usually (historically?) seen in older cats, caused by eating a liver-based diet

Question 18

Which is true of Hypervitaminosis A:

A. It causes osteopenia
B. The changes are most apparent in the lumbar vertebrae.
C. The shoulder and elbow joints have the most pronounced changes.
D. It causes widened physes.

Answer 18

A. It causes osteopenia.
C. The shoulder and elbow joints have the most pronounced changes.

Most pronounced in cervical spine, and shoulder and elbow (cranial part of the cat)
There is marked ankylosing spondylopathy and periarticular enthesopathy.

Question 19

Physeal thickening is a feature of:

A. Hypervitaminosis A
B. Nutritional secondary hyperparathyroidism
C. Renal secondary hyperparathyroidism
D. Rickets

Answer 19

Rickets - it is one of the defining features. Consequently, there is also metaphyseal flaring and cortical thinning.

Question 20

Put these in the correct chronological order of occurrence during development of osteoarthrosis:

• Formation of osteophytes and enthesophytes
• Increased subchondral opacity
• Calcification in and around the joints.
• Bony remodelling of normal joint contours

Answer 20

1. Increased subchondral opacity
2. Bony remodelling of normal joint contours
3. Formation of osteophytes and enthesophytes
4. Calcification in and around the joints.

Question 20

What is the most common primary joint neoplasm? what are some others?

Answer 20

Most common: synovial cell sarcoma

Others:
- Histiocytic sarcoma (shorter survival when comapred to SCS - Craig et al., 2002)
- Synovial myxoma
- Malignant fibrous histiocytoma
- Fibrosarcoma
- Chondrosarcoma

Question 20

What are synovial cysts? (where do they arise from, are they benign or malignant)

Answer 20

They are benign (but can become very large), and arise from the synovium or tendon sheath or bursa

Question 21

What is typical of joint neoplasms that is rare with other neoplasms?

Answer 21

Invasion of bone on either side of a joint (polyostotic)

Question 21

In which species is villonodular synovitis more reported?

Answer 21

Horses

Question 21

7yr Oriental cat

Answer 21

There is a arge continuous zone of proliferative new bone and several smaller osseous bodies at the medial aspect of the stifle in the region of the medial collateral ligament and medial joint capsule. Surgical exploration and histopathological diagnosis were consistent with synovial osteochondromatosis.

Question 21

Which of these is autosomal dominant?
A. Mucopolysaccharidosis
B. Osteochondrodystrophy of Scottish Fold cats
C. Alaskan Malamute chondrodysplasia
D. Avascular necrosis of the femoral head
E. Incomplete ossification of the humeral condyle

Answer 21

B. Osteochondrodystrophy of Scottish Fold cats

Question 22

Why would villonodular synovitis be confused with a neoplasm?

Answer 22

Because the fibrous mass that develops with this condition, can secondarily result in adjacent bone destruction

Question 23

How might rodenticide toxicity or von Willebrand’s disease affect a joint?

Answer 23

It can cause haemarthrosis (bleeding into the joint space). This can (chronically) damage the cartilage and subsequently the subchondral bone.

Question 24

Which signalment is overrepresented by calcinosis circumscripta?

Answer 24

young large-breed dogs, esp. GSD

Question 25

old cat

Answer 25

Hypervitaminosis A; extensive ankylosing spondylopathy of the cervical vertebrae and arthrosis of the shoulder joint (both typical locations)

Question 26

Dog

Answer 26

fragmented MCP