Developmental Orthopedic Disease

Question 1

What is the most common signalment for panosteitis? What is the pathophysiology?

Answer 1

male young, large breed dogs of 5-14 months (and Basset Hounds)

inflammation and increased osteoblastic/fibroblastic activity results in fibrosis and mineralization in the medullary cavity

Question 2

What is the most common imaging finding associated with panosteitis?

Answer 2

medullary cavity will have increased opacity usually by the nutrient foramen —> usually more lucent due to the presence of fat and trabeculae

Question 3

What 3 species of dogs typically develop osteochondrosis (osteochondritis dissecans)?

Answer 3

1. Labrador Retrievers
2. GSD
3. Rottweilers

(rapidly growing, medium/large breeds)

Question 4

What is the pathophysiology of osteochondrosis (osteochondritis dissecans)?

Answer 4

failure of endochondral ossification causes the epiphyseal cartilage to become too thick, leading to decreased synovial fluid diffusion, avascular cartilage, and cartilage necrosis

• typically results in the development of clefts or fissures from subchondral bone to articular cartilage surface

Question 5

How do patients with osteochondrosis (osteochondritis dissecans) present?

Answer 5

lamenss —> typically bilateral, so both limbs should be evaluated

Question 6

What are the 3 imaging features of osteochondrosis (osteochondritis dissecans)? What 4 joints are most commonly affected?

Answer 6

1. flattening of subchondral bone
2. regional sclerosis
3. mineralized osteochondral fragment (dissecans) dissected away from the articular surface

• humeral head
• humeral trochlea
• femoral condyles
• medial trochlear ridge of talus

Question 7

What imaging features of osteochondrosis (osteochondritis dissecans) are present in this radiograph?

Answer 7

• flattened subchondral bone
• increased opacity of subchondral bone
• regional sclerosis
• flapping + thin mineral fragments

Question 8

What patients most commonly present with hypertrophic osteodystrophy? What bones are most affected?

Answer 8

rapidly growing, large and giant breeds from 3-7 months of age

distal radius/ulna

Question 9

What is thought to be the etiology of hypertrophic osteodystrophy? How do patients present?

Answer 9

viral etiology —> distemper (vaccine)

systemic disease - fever, lethargy, diarrhea, nasal discharge, lameness, swelling

Question 10

How does hypertrophic osteodystrophy initially look on radiographs? How does it develop?

Answer 10

pseudophyseal lines = “double physis” (bilaterally symmetrical)

• collar of extra-cortical bone with surround the metaphysis toward the diaphysis, separated by a radiolucent line and superimposing over the distal metaphysis
• collar will eventually fuse with the cortex and remodel, becoming sclerotic

Question 11

What is hypertrophic osteopathy? What is the most common radiographic sign?

Answer 11

osseous change that occurs secondary to a thoracic or abdominal mass

pallisading periosteal reactions starting distally and moving proximally, typically starting on the abaxial surfaces of metacarpal/metatarsal 2/5 (bilateral, spares joints)

Question 12

What are the main differences between hypertrophic osteodystrophy and osteopathy?

Answer 12

OSTEODYSTROPHY - young, growth disruption/endochondral ossification, early lucencu in metaphysis with double physis, later periosteal bone, angular limb deformity

OSTEOPATHY - older, pulmonary or urinary bladder masses, always periosteal new bone with increased opacity

Question 13

What dog breed most commonly develops retained cartilage cores? What is the pathophysiology?

Answer 13

giant breeds —> Irish Wolfhounds 4 months and older

temporary inadequate blood supply to metaphysis causes a central core of cartilage to not transform into bone, commonly resulting in angular limb deformity

Question 14

What are the 2 most common imaging findings in patients with retained cartilage cored?

Answer 14

1. triangular, “flame-like”, radiolucent wedge in distal metaphysis of ulna
2. cranial bowing of the radius due to premature closing of the ulnar physis

Question 15

What is the most common cause of angular limb deformities?

Answer 15

asynchronous growth of long bones or aberrant forced

• early physeal closure of one bone and not the other

(distal ulnar physis is responsible for 80% of lengthening)

Question 16

What are the 3 most common causes of angular limb deformities?

Answer 16

1. genetic in chondrodystrophic breeds, like Dachshunds and Lhasa Apsos
2. traumatic injury to physes
3. medial patellar luxation

Question 17

What is the pathophysiology of angular limb deformities? What 2 deformations result?

Answer 17

injury or interruption of the physis results in the premature closure or asynchronous growth of long bones

1. VALGUS = lateral deviation of digits and carpus/tarsus relative to the distal antebrachium/crus
2. VARUS = medial deviation of the digits and carpus/tarsus relative to the distal antebrachium/crus

Question 18

What are 2 imaging findings seen in this radiograph of an angular limb deformity?

Answer 18

1. retained cartilage core (likely cause of premature physis closure)
2. lateral deviation of carpus

Question 19

What are 2 imaging findings seen in this radiograph of an angular limb deformity?

Answer 19

1. premature closure of distal ulnar physis
2. cranial bowing of radius

Question 20

What is the congenital malformation, agenesis? What bones are most affected?

Answer 20

hypoplasia of bone, resulting in complete or partial absence of the bone or abnormal bones

radius, ulna, tibia

Question 21

Classify the developmental orthopedic diseases seen in these radiographs:

Answer 21

1. osteochondrosis
2. panosteitis
3. hypertrophic osteodystrophy
4. angular limb deformity