Musculoskeletal pathology - Joint

Question 1

Types of Joints

Answer 1

◼ Diarthroses > Synovial joints
◼ Amphiarthroses > Vertebral discs
◼ Synarthroses > Sutures of skull
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(Di – two; amphi – both; Syn - together)

Question 2

Composition of diarthrodial joints

Answer 2

◼ Articular cartilage
◼ Synovial fluid
◼ Synovial membrane

Question 3

Constituents of Articular cartilage, and what the parts do?

Answer 3

Water
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Gel
◼ Chondrocytes
> Maintain cartilage, but no remodel
> Limited proliferation (chondrones)
◼ Collagen type 2
> loops
◼ Proteoglycans
> Protein core
> Glycosaminoglycans (glucosamine + others)

Question 4

Synovial Fluid
- composition, how it is made?

Answer 4

◼ Pressure on cartilage forces out fluid, provides flushing action.
◼ Hyaluronic acid, nutrients, lubricin!
◼ Production by secretory synovial cells (fibroblastic synoviocytes)

Question 5

Synovial cells (synoviocytes)
- types and what they do?

Answer 5

Phagocytic synovial cell
◼ Aka phagocytic synoviocyte
◼ histiocytic dendritic cell
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Secretory synovial cell
◼ fibroblast like synoviocyte
◼ produces synovial fluid

Question 6

Response of Joint to Injury:
Cartilage Injury and Degeneration

Answer 6

Injury
> Trauma
> Joint instability
◼ Failure of synovial fluid
◼ Enzyme activation
◼ Chondrocyte necrosis
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◼ Degeneration
◼ Fibrillation
◼ Ulceration
◼ Eburnation

Question 7

Response of Joint to Injury: Joint Disease:
Degenerative joint disease
> of cartilage and joint capsule

Answer 7

Cartilage
◼ Erosion
◼ Eburnation > (polished)
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Joint capsule
◼ Synovial hyperplasia
◼ Capsular fibrosis

Question 8

Response of Joint to Injury: Joint capsule

Answer 8

◼ Synovial membrane
> Synovial cell hyperplasia
> Villous hyperplasia
◼ Synovial membrane inflammation and altered synovial fluid
◼ Pannus
> granulation tissue
◼ Periarticular fibrosis
◼ Osteophytes
> Bone and fibrocartilage protrusions

Question 9

Diseases of Joints

Answer 9

Degenerative joint disease
Arthritis
Osteochondrosis
Neoplasia

Question 10

Degenerative joint disease - predisposing factors / causes

Answer 10

◼ Age
> Wear and tear
> Microtrauma
◼ Injury to
> Synovium
> Cartilage
> Subchondral bone
◼ Performance animals
◼ Osteochondrosis

Question 11

Arthritis - types, who they are found in

Answer 11

Bacterial
◼ Rare in dogs and cats
◼ Common in piglets, foals and calves
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Immune mediated
◼ Dogs and cats

Question 12

Osteochrondrosis (OC)
- what is it? what is affected?
- 3 types

Answer 12

◼ Definition: Local failure of endochondral ossification
◼ Articular and physeal cartilage types
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Articular OC
◼ OC latens (OCL)
> latens – hidden, secret, unknown
◼ OC manifesta (OCM)
> manifesta - clear or conspicuous
◼ OC dissecans (OCD)
> dissec - to separate

Question 13

Osteochrondrosis - why does it happen?

Answer 13

Vascular failure of growth cartilage
◼ Thrombosis of vessels
> acquired infectious
> endotoxemia
◼ Developmental
◼ Biomechanical
◼ Dietary imbalance

Question 14

Articular osteochrondrosis (OC) pathogenesis

Answer 14

◼ Death of epiphyseal growth cartilage at critical age
> 7 weeks in pigs
> Infarct = OC latens
◼ Failure of ossification, retention of cartilage > OC manifesta
◼ Split of articular cartilage
> OC dessicans

Question 15

Physeal Osteochondrosis
- what is it? causes?

Answer 15

◼ Separation of epiphysis from metaphysis
◼ Trauma associated
> Pigs – separation of ischial tuberosity
> Dogs – ununited anconeal process
> Horses – articular facets of vertebral column

Question 16

Elbow dysplasia in dogs - reasons

Answer 16

◼ Ununited coronoid process
◼ Ununited anconeal process
◼ Degenerative joint disease

Question 17

Neoplasia of the joint
- how are they named? what types are there?

Answer 17

◼ Naming based on phenotype of synovial cells
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Phagocytic synovial cells
◼ Periarticular histiocytic sarcoma
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Secretory synovial cells
◼ Synovial myxoma/myxosarcoma
◼ Synovial fibroma/fibrosarcoma