MSK Lecture 5

Question 1

For panoesteitis:

1. Describe how the condition typically appears radiographically
2. The signalment of dog that is usually affected by the condition

Answer 1

Radiographic appearance:

• Starts as circumscribed nodular opacities in the diaphysis of long bones
• Progresses to diffuse homogenous opacity in medulla + smooth solid periosteal new bone in diaphysis

Signalment of dog affected:

• Young dogs

Question 2

For hypertrophic osteodystrophy:

1. Describe the radiographic appearance of it
2. The sites it typically occurs at
3. The signalment of animal that is affected

Answer 2

Radiographic appearance of it:

• Transversly orientated radiolucent zones within the metaphysis
• Parallel and adjacent to physis
• Appears as a “double physis sign” - area of radiolucency

Site:

• Distal radius, ulnar and tibia

Signalment:

• Young dogs

Question 3

Describe the appearance of premature closure of the distal ulnar physis and the four secondary abnormalities that can develop as a result:

Answer 3

Radiographic appearance:

• Distal ulnar physis - lack normal radiolucent line
• Distal radial physis - lucent line remains

Secondary findings:

• Radius appears curved
• Valgus if partial physeal closure
• Elbow joint incongruity + subluxation
• Degenerative joint disease

Question 4

For retained cartiladge cores and growth defects:

1. Describe the signalment of dog that is usually affected and location
2. What is the cause of this defect
3. Describe the appearance of it

Answer 4

Signalment of dog:

• Distal ulnar of large breed dogs

Cause:

• Caused by a disruption of endochondral ossification

Appearance:

• Cone shaped radiolucent zone in the distal ulnar metaphysis

Question 5

For osteochondrosis and osteochondritis dissecans:

1. Differentiate between these two conditions
2. What are the four specific predilection sites that are seen in dogs

Answer 5

• Osteochondrosis (general disease syndrome) whereas osteochondritis dissecans involves the formation of an actual flap

Locations seen in the dog:

1. Caudal proximal humerus
2. Medial condyle of distal humerus
3. Medial and lateral trochlear ridges of the talus
4. Medial and lateral condyles of the distal femur

Question 6

For an united anconeal process:

1. State when this condition can be diagnosed
2. The radiographic appearance of it
3. What types of breeds are particularly predisposed to this condition

Answer 6

1. Fusion occurs at 4-6 months - seen in large breed dogs (GSD)
2. Radiographic appearance of it: Radiolucent line seperating anconeal process from the olecranon
3. Large breed German Shepard dogs

Question 7

Describe how a fragmented medial coronoid process (FCP) of the ulnar appears:

Answer 7

• Abnormal contour poor definition cranial margin coronoid
• Rounded blunt shape

Question 8

Describe the pathogenesis of hip dysplasia:

Answer 8

1. Subluxation of femoral head
2. Malformation of the joint
3. Secondary DJD

Question 9

For hypertrophic osteopathy:

1. Described the usual signalment of dog affected
2. Describe the appearance of it on a radiograph
3. Normally associated with….

Answer 9

Signalment:

Older dogs

Appearance of the radiograph:

• PNB - irregular to pallisading
• Diaphyseal distribution
• Multiple limbs and bones
• Metacarpals and metatarsals

Associated with:

• Thoracic + abdominal mass lesions

Question 10

Briefly describe how new bone appears in:

1. Normal fracture healing
2. Motion
3. Infection

Answer 10

Normal fracture healing:

• Smooth + solid homogenous PNB
• Active until healed
• Location up to 2cm above + below the healing site

Motion:

• Irregular or excessive PNB
• Extending further into adjacent tissue
• Implant failure + delayed healing

Infection:

• Irregular to pallisading PNB
• Long and low
• Osteolysis - geographic to moth eaten

Question 11

Rank your differentials for a solitary metaphyseal Aggressive Bone Lesion in Large or Giant Breed:

1. How would your differentiate between them?

Answer 11

Differential list:

1. Primary bone tumour
2. Mycotic osteomyelitis
3. Other tumour
4. Bacterial osteomyelitis

⇒ use a biopsy to differentiate

Question 12

Rank your differentials for a bone lesion that is solitary or polystatic, aggressive to very aggressive, located on metaphysis or on the diaphyseal region:

Answer 12

1. Mycotic osteomyelitis
2. Metastatic tumour
3. Bacterial osteomyelitis

Question 13

What are the main predilection sites for osteosarcoma?

Answer 13

1. Proximal humerus
2. Distal radius
3. Distal femur
4. Proximal and distal tibia

Question 14

What are the three Ddx for radiolucency throughout the whole body?

Answer 14

• Generalised osteoporosis
• Secondary nutritional hyperparathyroidism
• Nutritional, metabolic, hormonal studies

Question 15

What is the radiographic diagnosis for radiolucency confined to a single limb?

Answer 15

• Disuse osteoporosis