Cartilage Development and Joint Dx (Pead)

Question 1

What is a “joint” composed of? (tissue wise)

Answer 1

• bone
• cartilage
• joint capsule
• ynovial membrane
• synovial fluid
• ligaent
• tendon

Question 2

What zones does the end of a juvenile long bone consist of?

Answer 2

• metaphysis
• physis (growth plate)
• epiphysis (covered in cartilage)
  > cancellous bone to spread the load

Question 3

Wht may be seen at the end of an adult longn bone?

Answer 3

” suture line” where growth plate closed (not a physis)

Question 4

Why do limb deviations result?

Answer 4

• damage to the physis, eg.
  > ridge within joint
  > bridging of bone across the physis

Question 5

What are lateral and medial deviations of the limbs referred to as?

Answer 5

• valgus deformity = lateral deviation of the distal limb

- varus deformity = medial

Question 6

Whicch way will the limb deviate if physis is demaged?

Answer 6

Towards the side of damae

Question 7

Is it normal for the epiphysis to expand during growth?

Answer 7

Yes

Question 8

What is “osteochondrosis”? eg?

Answer 8

• term for a group of conditiions affecting the developing cartilage and its supporting bone
• eg.
  > OCD (osteochondrosis dessicans)
  > Subchondral bone cyts (SBC)
  > Peri-aritcular fx/fragmentation
• NB. human medical textbooks this refers to a more specific dz

Question 9

Most common eg. of peri-articular fragmentation/fx?

Answer 9

• detachment of chondral or oseteochondral fragment fromt he peri-aritcular area
• eg. canine elbow (frag/fx of MEDAL CORONOID PROCESS) FCP/FCMP

Question 10

What is osteochondrosis initiated by?

Answer 10

• vascular problem in the epiphysis

- failure of normal cartilage bone succession

Question 11

Outline the pathogenesis of osteochondrosis dessicans

Answer 11

• section of wedge of epiphysis does not turn into bone, emain cartilagenous
• fissures develop
• wedge stuck down by fibrous repair tissue
• OR break off and float into joint capsule, causing abnormal wear elsewhere in the joint

Question 12

How does a subchondral bone cyst form?

Answer 12

• excessive cartilage in one section of the bone
• beins ossifying again
• isolated area of cartilage bubble under the surface (weak spot) changes loading of the joint, might be painful, unstable etc.
  > most common horses

Question 13

Where is osteochondrosis commonly seen?

Answer 13

> dogs
- OCD, FCP fragmented choronoid proces), UAP (ununited anconeal process)
- esp. elbow shoulder, stifle, tarsus + otehrs
Horses
- OCD, SBC
- stifle, tarsus, MCP, PIP, DIP, shoulder, elbow, carpus
pigs
- OCD esp hip
broiler chickens
- OCD stifle
all fast growing, high performance, YOUNG patients

Question 14

Presentation of ocd?

Answer 14

+- joint effusion

• often bilateral
• • varibale lameness
• subclinical dz possible
• large, young, fast growing, purebred
• excericse intolerant
• partially responsive to analgesia
• partially responsive to rest
• Pain on MANIPULATION of affected joint

Question 15

First plan of action for investigating joint dz?

Answer 15

• radiographs

Question 16

Tx of joint OCD? (juvenile,d evelopmental dz)

Answer 16

> symptomatic 
> conservative
> surgical 
- open
- arthroscopy
- fragment removal 
- encourage repair (fibrocartilage, rarely get hyaline cartilage back) 
> generally prognosis variable
- related to formation OA
- shoulder forms little OA (so prognosis is good) cf. elbow (prognosis poor)

Question 17

How does OA differ in animals to humans?

Answer 17

> humans commonly aging process
animals 2* to 1* predisposing disease
- worsened or exacerbate by age

Question 18

How can fragented medial choronoid process by visualised?

Answer 18

• NEeds CT

Question 19

Tx elbow elbow medial choronoid process fragent?

Answer 19

> symptomatic
> conservative 
> surigcal 
- open 
 - arthroscopy 
- fragment removal
- encourage repair
> novel tx that change anatomy
> prognosis complicated
- depends on degree of OA
- may need salvage  (salvage procedure/joint replacement)

Question 20

What must you be careful of when manipulating joints?

Answer 20

• holding bones t oo tightly

- panosteitis can be confused for joint pain

Question 21

How does osteochondrosis lead to OA?

Answer 21

• irritation
• direct cartilage damage
• incongruency, mechanical incompetence
• cycle of reaction
• often temporarily stabilises in young adult

Question 22

Prog for OCD/O in a young animal?

Answer 22

Not likly to excercsie maximally but otherwise life prog good! Dont be too negativve with owners.

Question 23

What is the purpose of hyaline cartilage?

Answer 23

• interface between bones at a synovial joint
• complex matrix of: collage, proeoglycans, water
• resists compressive forces
• resident cells (chondrocytes) responsible for turnover (breakdown and synthesis of matrix)