Lecture 4

Question 1

What are the characteristics of a normal hip joint?

Answer 1

-at least 50% of femoral head is covered by dorsal acetabular rim
-femoral neck narrower than head
-femoral neck has smooth margin
-parallel margin between acetabulum and femoral head

Question 2

What are the characteristics of hip dysplasia?

Answer 2

-abnormal hip laxity which results in DJD
-mainly in large breed dogs
-bilateral laxity; DJD may be unilateral or bilateral
-inherited condition

Question 3

What are the characteristics of a standard VD view for hip dysplasia assessment?

Answer 3

-pull legs straight back and rotate inward
-open collimation to include entire pelvis and both femurs through to the stifles

Question 4

How does rotation affect the apparent degree of acetabular coverage?

Answer 4

Rotated Right:
-decreased right acetabular coverage and increased left acetabular coverage
-right acetabulum looks small, left acetabulum looks large

Rotated Left:
-decreased left acetabular coverage and increased right acetabular coverage
-left acetabulum looks small, right acetabulum looks large

Question 5

What are the Roentgen signs of hip dysplasia?

Answer 5

-shallow, flattened acetabulum
-inadequate femoral head coverage: wedging, subluxation, luxation
-periarticular osteophyte production along cranial and dorsal acetabular rims and around femoral head and neck
-Morgan’s line

Question 6

What are the characteristics of Morgan’s line?

Answer 6

-aka caudal curvilinear osteophyte
-sign of joint laxity
-osteophyte formation along caudal femoral neck and enthesophytes at attachment of joint capsule

Question 7

What is shown in these radiographs?

Answer 7

hip dysplasia
-minimal coverage of femoral head
-flattened, sclerotic femoral head
-no femoral neck present
-osteophyte formation and sclerosis

Question 8

What is outlined in these radiographs?

Answer 8

Morgan’s line

Question 9

What are the characteristics of OFA hip evaluation?

Answer 9

-based on extended leg VD view only
-dog must be > 24 months for final grading
-does not require chemical restraint

Question 10

What are the grades for OFA hip evaluation?

Answer 10

-excellent
-good
-fair
-borderline
-mild dysplasia
-moderate dysplasia
-severe dysplasia

Question 11

What are the characteristics of PennHIP?

Answer 11

-gives a quantitative evaluation of joint laxity
-compares to breed medians
-does not tell you if there is hip dysplasia unless dog has DJD
-examiners must be certified
-requires extended leg VD, compression VD, and distraction VD with distraction apparatus

Question 12

What is shown in this image?

Answer 12

extended leg VD, compression VD, and distraction VD required for PennHIP evaluation

Question 13

What is the distraction index for hip dysplasia?

Answer 13

-0 indicates tightest hip, 1 indicates completely luxated hip
-measures displacement of femoral head on distraction view
-0.3 is the normal DI
-the higher the DI, the higher the probability of developing DJD
-DI standards will vary by breed

Question 14

What are the characteristics of aseptic necrosis of femoral head (Legg-Calve-Perthes dz)?

Answer 14

-seen in immature toy and small breed dogs
-bilateral less than 15% of the time
-compromised blood supply to proximal femoral epiphysis leads to necrosis of subchondral bone

Question 15

What is the normal blood supply to the femoral head?

Answer 15

-synovial membrane (sole supply in puppies)
-arteries in round ligament of head of femur
-nutrient vessels through metaphysis

Question 16

What are the Roentgen signs of aseptic necrosis of femoral head?

Answer 16

-increased width of joint space; articular cartilage thickens
-irregular opacity of femoral head
-patchy regions of osteolysis in femoral head
-deformity and flattening of femoral head
-DJD due to abnormal articulation and osteophyte formation

Question 17

What is shown in this radiograph?

Answer 17

-normal right hip
-aseptic necrosis of femoral head in left hip

Question 18

What is shown in this radiograph?

Answer 18

deformity and flattening of right femoral head due to aseptic necrosis of femoral head

Question 19

What is shown in this radiograph?

Answer 19

osteophyte formation on acetabular rim due to aseptic necrosis of femoral head

Question 20

What are the characteristics of patellar luxation?

Answer 20

typically young, small breed dogs but also in large breeds
-medial luxation in small breeds
-lateral luxations in large breeds
-typically congenital/developmental but can be traumatic
-associated with malalignment of quadriceps due to rotation and/or deformity of femur and/or tibia

Question 21

What are the Roentgen signs of medial patellar loxation?

Answer 21

-patella medial to trochlear groove
-lateral bowing of distal femur
-medial bowing of proximal tibia
-medially located tibial tuberosity and quadriceps
-shallow trochlear groove
-secondary DJD

Question 22

What is shown in this radiograph?

Answer 22

lateral bowing of distal femur and medial bowing of proximal tibia consistent with MPL

Question 23

What is shown in this radiograph?

Answer 23

MPL; patella overlapping with femur rather than sitting in trochlear groove

Question 24

What are the characteristics of hypertrophic osteopathy?

Answer 24

-middle aged to older dogs
-secondary to concurrent thoracic or abdominal dz; often pulmonary neoplasia
-gradual or occasional acute onset of lameness
-animal reluctant to move
-symmetric, non-edematous, firm swelling of the distal limbs

Question 25

What are the Roentgen signs of hypertrophic osteopathy?

Answer 25

-solid, irregularly marginated periosteal reaction (palisading/columnar) -never confined to a single location; bilateral or generalized -begins on abaxial surface of 2nd and 5th metacarpal/metatarsal bones and progresses proximally -spares small bones of carpus and tarsus -periosteal reaction located at diaphysis of tubular bones

Question 26

What is shown in this radiograph?

Answer 26

hypertrophic osteopathy

Question 27

What is shown in this radiograph?

Answer 27

hypertrophic osteopathy

Question 28

What are the characteristics of fungal osteomyelitis?

Answer 28

-young to middle-aged dogs -any breed; more common in large working or sporting breeds -usually hematogenous in origin -usually systemically ill

Question 29

What are the Roentgen signs of fungal osteomyelitis?

Answer 29

-combination of lysis and production -active and aggressive or semi-aggressive changes -cortical lysis possible -sclerosis in adjacent medullary region -occurs in metaphysis of long bones -joint involvement with extensive bone destruction -often polyostotic but can be monostotic

Question 30

What is shown in these radiographs?

Answer 30

fungal osteomyelities

Question 31

What are the characteristics of bacterial osteomyelitis?

Answer 31

-often secondary to direct inoculation or an extension from soft tissue injury -can be hematogenous in young or immunocompromised animals

Question 32

What are the Roentgen signs of bacterial osteomyelitis?

Answer 32

-severe soft tissue swelling -periosteal reaction extending along shaft of diaphysis; lamellar, columnar, or solid depending on age

Question 33

Where is bacterial osteomyelitis located based on origin?

Answer 33

*Non-Hematogenous: -based on affected area -may affect multiple bones in same limb -lucencies around surgical implants -draining tracts *Hematogenous: -metaphyseal due to extensive capillary network -often polyostotic

Question 34

What are the differential diagnoses for bacterial osteomyelitis?

Answer 34

-healing fracture -primary or metastatic bone tumor -fungal osteomyelitis

Question 35

What is shown in these radiographs?

Answer 35

bacterial osteomyelitis

Question 36

What are the characteristics of primary bone tumors?

Answer 36

-more common in large and giant breeds -mean age of 7 years; bimodal distribution with another peak at young ages -slightly more common in male dogs -causes lung metastases most commonly -can metastasize to other bones

Question 37

What are the Roentgen signs of primary bone tumors?

Answer 37

-can be osteoblastic, osteolytic, or both -aggressive -monostotic -metaphyseal region of long bones -do not usually cross the joint

Question 38

Which bone tumors are most commonly seen?

Answer 38

-osteosarcoma (>85%) -chondrosarcoma -fibrosarcoma -hemangiosarcoma

Question 39

What is shown in these radiographs?

Answer 39

primary bone tumors

Question 40

What are the characteristics of radiographs for fracture evaluation?

Answer 40

-need two orthogonal views (90 deg. to one another) -want to include joint proximal and distal to fracture -consider special views to determine full extent of fracture

Question 41

How can fractures be recognized on radiographs?

Answer 41

-most present as abnormal radiolucent lines -compression fractures may lead to alterations in size or opacity

Question 42

What are the characteristics of non-displaced fracture recognition?

Answer 42

-may only be seen days later when resorption occurs at fracture margins -others are not seen until bony callus starts to form -nuclear medicine/bone scan may pick up what radiographs cannot

Question 43

What are the fracture types?

Answer 43

-open vs closed -incomplete vs complete -simple vs complex/comminuted -transverse, oblique, or spiral -extra-articular, articular, compression, avulsion -displaced vs non-displaced

Question 44

What are the characteristics of primary bone healing?

Answer 44

-occurs with rigid internal fixation -results in bony union through direct growth of haversian system across fracture -minimal to no bony callus -cannot occur across a fracture gap -usually occurs with compression plate reduction

Question 45

What are the radiographic signs of primary bone union?

Answer 45

-lack of callus -gradual loss in opacity of fracture ends -progressive disappearance of fracture line

Question 46

What is shown in these radiographs?

Answer 46

progression of primary bone union

Question 47

What are the characteristics of secondary bone healing?

Answer 47

-lack of rigid internal fixation and excellent anatomic reduction -reaction stage consists of hematoma formation, inflammation, and granulation tissue -repair consists of cartilaginous callus formation and lamellar bone deposition -bone eventually remodels -most common type of fracture healing in small animals

Question 48

What is shown in these radiographs?

Answer 48

progression of secondary bone healing

Question 49

What factors can affect bone healing?

Answer 49

-fracture location -vascular integrity -degree of immobilization -fracture type -degree of anatomic reduction -degree of soft tissue trauma -degree of bone loss -type of bone involved -presence of infection -local malignancy -metabolic factors

Question 50

What should be evaluated on post-op fracture radiographs?

Answer 50

-alignment of fracture fragments -apposition of fracture fragments -apparatus used for reduction and stability -activity/callus formation