Osteochondrosis

Question 1

Mechanism of increased length of long bones

Answer 1

Endochondral Ossification at the level of the physis

Question 2

Endochondral ossification

Answer 2

1. Osteoblasts migrate from perichondrium into cartilage, cause calcification of cartilage matrix.
2. Osteoclasts migrate into calcified cartilage via capillaries to resorb tissue, leaving trabecular bone

Question 3

OC lesions thought to be result of

Answer 3

Failure of endochondral ossification resulting in excessively thick epiphyseal cartilage

Question 4

Radigraphs

Answer 4

Areas of lucency or flattening of joint surface

Question 5

Area of retained cartilage is weaker and subject to

Answer 5

injury by normal or abnormal biomechanical forces

Question 6

OCD

Answer 6

Cartilage flap, fragmentation, or abnormal cartilage breaking off and loose in the joint

Question 7

OC etiology

Answer 7

1. Exercise
2. Nutrition
3. Genetics
4. Trauma

Question 8

Exercise

Answer 8

• Important for maturation of musculoskeletal tissues

- Some vague association between restricted exercise and OC

Question 9

Nutrition

Answer 9

1. Rapid growth often a culprit
2. Low Copper, High zinc-effect on repair?
3. High phosphorus-sign inc OC lesions
4. High digestible energy

Question 10

Genetics

Answer 10

• Complex and Polygenic

- Thoroughbreds, Standardbreds, Warmbloods

Question 11

Trauma

Answer 11

Not been proven, considered an additive factor

Question 12

Most common joints

Answer 12

1. Femoropatellar
2. Tarsocrural
3. Metacarpo/metatarsophalangeal

Question 13

DDX acute severe lameness

Answer 13

1. OC/OCD
2. Septic joint
3. Articular fracture

Question 14

Common silent lesion

Answer 14

Medial malleolus of tibia

-may require arthroscopy

Question 15

Lesions that won’t resolve spontaneously

Answer 15

1. Tarsocrural joint lesions after 5 months old

2. Femoropatellar lesions after 8 months old

Question 16

Treatment considerations surgery vs conservative tx

Answer 16

1. Lameness
2. Free fragments-indicates surgery
3. Effusion
4. Sale pressure

Question 17

Conservative treatment

Answer 17

1. Rest/controlled exercise
2. NSAIDS
3. Intra-articular therapies
4. Systemic joint therapies

Question 18

Intra-articular therapies

Answer 18

1. Hyaluronic acid
2. Corticosteroids
3. IRAP
4. PRP
5. Stem cells

Question 19

Systemic joint therapies

Answer 19

1. PSGAGs
2. Hyaluronic acid
3. Neutraceuticals

Question 20

Surgery

Answer 20

1. Arthroscopic debridement
2. PDS pins
3. Grafts (stem cells, PRP, BMAC, etc)

Question 21

Be cautious in young animals

Answer 21

Normal bone is soft in young animals and debridement may result in excess trauma

Question 22

Subchondral bone cysts

Answer 22

1. form beneath articular cartilage at sites of major weight bearing, occasionally in active physis
2. Osteolysis surrounded by sclerotic rim, lined by myxomatous and fibrous tissue w/variable amount fluid

Question 23

Cause of bone cysts

Answer 23

1. Hydraulic theory-slit in articular cartilage

2. Inflammation theory-fluid within cyst excretes inflammatory stuff

Question 24

Most common location

Answer 24

Medial femoral condyle of distal femur

OFTEN BILATERAL

Question 25

Common Breeds

Answer 25

1. Thoroughbreds and quarterhorses | 2. Warmbloods have a greater distribution of lesions within phalanges (including navicular bone)

Question 26

Diagnosis

Answer 26

1. Lameness - Effusion-single/multiple joints - Positive flexion - Variable response to joint injections 2. Radiographs

Question 27

Conservative tx OC

Answer 27

1. Rest 2. NSAIDs 3. Intra-articular medication - corticosteroids, HA, IRAP, PRP, stem cells - Intra-lesional injection steroids (triamcinolone)

Question 28

Surgical tx OC

Answer 28

1. Arthroscopic debridement 2. Transosseous drilling and debridement 3. Intralesional corticosteroid injection 4. Grafting - Autologous cancellous bone graft - Tricalcium phosphate

Question 29

Femoropatellar joint signs

Answer 29

1. joint distension 2. variable lameness-bunny hop 3. often bilateral

Question 30

Femoropatellar joint dx

Answer 30

1. Lateral and caudolateral-craniomedial oblique | 2. Lateral trochlear ridge most common

Question 31

Femoropatellar joint tx

Answer 31

1. > 8 months old Surgical arthroscopic debridement if athletic career expected - 60-70% return to use - if large lesion and on patella OA likely 2. Small lesion maybe rest and HA injection - fair to poor prog

Question 32

Tarsocrural joint signs

Answer 32

1. Bog spavin most common 2. lameness mild 3. CS with trochlear ridge lesions 4. CS rare w/ distal tibia lesions until training 5. Often bilateral

Question 33

Tarsocrural joint dx

Answer 33

1. rads, or arthroscopy for unresolved cases

Question 34

Tarsocrural joint tx

Answer 34

1. Distal intermediate ridge lesions removed for racing, otherwise NBD 2. Medial malleolus-debridement or effusion persists 3. Trochlear ridge lesions need arthroscopic debridement to prevent OA

Question 35

Tarsocrural joint prognosis

Answer 35

1. Arthroscopy-75-80% return to intended use 2. Trochlear ridges of talus fair to good for racing soundness after sx 3. Distal intermediate ridge or malleoli of tibia-EXCELLENT

Question 36

Fetlock joint signs

Answer 36

1. Young horses 6-24 months 2. Fetlock joint capsule distension 3. Mild-mod lameness if dorsal MCIII or MTIII 4. Ush very lame ifsubchondral cyst of MCIII 5. Intra-articular anesth often unecessary

Question 37

Fetlock joint dx

Answer 37

1. Lameness exam 2. Rads 3. Sagittal ridge lesions usually bilateral - often quadrilateral

Question 38

Fetlock joint tx

Answer 38

1. Sagittal ridge OCD flaps: conservative tx, rest and HA injections 2. Persistent lameness/swelling: surgical tx via arthroscopy 3. Subchondral cysts: conservative therapy/arthroscopic debridement

Question 39

Fetlock joint prognosis

Answer 39

1. Arthroscopy-50-60% return to intended use (if distal sagittal ridge) 2. Guarded to poor w/ conservative tx subchondral cyst MCIII MTIII

Question 40

Shoulder joint signs

Answer 40

1. Stiff stilted gait-shortened cranial phase of stride 2. Shoulder pain on flexion/manipulation 3. Cant use detect effusion 4. Mod-severe lameness 5. Young horses 4-12 months old, often fast growing horses 6. Hx of acute onset

Question 41

Shoulder joint dx

Answer 41

1. Confirmed by rads 2. mid humeral head + glenoid cavity cysts 3. Intra articular anesthesia used, but variable response

Question 42

Shoulder joint tx

Answer 42

1. Time/HA, sx debridement 2. may progress to OA 3. Arthroscopic debridement of OCD slows progression OA, but poor race performance

Question 43

Shoulder joint prognosis

Answer 43

1. Guarded to poor without sx, possible euthanasia | 2. 20-45% success with surgery

Question 44

Femorotibial joint signs

Answer 44

1. Medial femorotibial AND femoropatellar joint pouch distension w/subchondral bone cysts 2. Variable lameness mild-severe 3. Often bilateral on rads even if unilaterally lame 4. Horses 6 months to 8 years old

Question 45

Femorotibial joint dx

Answer 45

1. Cranial-caudal rads 2. Intra-articular anesth inconsistent 3. Usually medial condyle of femur

Question 46

Femorotibial jont tx

Answer 46

1. Treat cases w/ severe lameness > 2 months 2. Initially rest and/or joint injection, can continue light work with bute 3. If lameness persists > 6 months surgery 4. Arthroscopic curettage of cyst contents, trim articular margins of cyst 5. Bone graft or osteogenic material 6. Screw across cyst? 7. Stem cells?

Question 47

Femorotibial joint prognosis

Answer 47

1. 60% return to soundness with surgery | 2. secondary OA or meniscal damage later is common

Question 48

Hip joint

Answer 48

1. Femoral head and acetabular cysts rare sites, difficult to dx 2. Not ush detected until racing

Question 49

Phalangeal cysts

Answer 49

1. Results in OA of coffin or pastern if cyst enters joint 2. Arthrodesis of pastern 3. often bilateral

Question 50

Cervial spine

Answer 50

1. OCD may be inciting cause of cervical vertebral instability 2. OCD of articular facets is common 3. Causes spinal cord compression with neuro dz, hindlimbs more severe 4. tx is cervical fusion.