18. Orthopaedic Diseases of Young and Growing Dogs and Cats Flashcards
1
Q
Pathophysiology of osteochondrosis / dissecans?
A
- Young (6-9Mo), rapidly growing, large breeds
- Epiphyseal cartilage necrosis -> Failure of endochondral ossification (may resume if vasculature can resuppy)
- Divots within subchondral bone, progressive chondromalacia
- Dissecans: flap, chondral or osteochondral fragment formation
=> ST, so not visualised radiographically
2
Q
List 5 common sites of OCD
A
- Caudal aspect of proximal humerus
- Distomedial aspect of humeral trochlea
- Lateral and medial femoralcondyles
- Femoral trochlea
- Lateral and medial talar ridges
3
Q
What is a kissing lesion?
A
- Subchondral defect that involves articular surface opposite primary (OCD) lesion
4
Q
Rx features of OCD?
A
- Flattening or concavity of affected subchondral bone
- Irregularity or widening of joint
- Sclerosis
- Joint effusion
- Capsular thickening
- Mineralised flap / joint mouse
=> may become vascularised / enlarge over time
5
Q
What causes the vacuum phenomenon in joints?
A
Traction -> accumulation of nitrogen gas.
=> Seen in shoulders with OCD
6
Q
What views of the talus may aid identification of lateral talar ridge OCD?
A
- Flexed dorsoplantar
- Dorsolateral - plantaromedial oblique
7
Q
What projections may aid in identification of shoulder OCD?
A
SUPINATED projections
8
Q
What normal structure may be mistaken for lateral femoral condyle OCD?
A
Extensor fossa - origin of long digital extensor
9
Q
Which contrast agents should be used for arthrographic evaluation of OCD?
A
- Non-ionic low osmolar -> Avoids dilution due to water-influx.
10
Q
List the 3 primary lesions (triad) involved in elbow dysplasia
A
- Ununited anconeal process
- Medial coronoid process fragmentation
- OCD of distomedialaspect of humeral trochlea
11
Q
Which 5 breeds have a seperate centre of ossification at the anconeal process?
A
- GSD
- Greyhounds
- Pit bull
- Lab
- G. Ret
12
Q
At what age should the anconeal process be fused?
A
150 days
13
Q
Which 4 breeds are at risk of UAP?
A
- Bernese
- Rotti
- Mastiffs
- St Bernards
*OTHER LARGE BREEDS*
14
Q
Which radiograph should be performed for suspected UAP?
A
Flexed lateral
15
Q
What is the most common developmental disorder involving canine elbow?
A
Fragmented MCP
16
Q
Clinical features of frag. MCP?
A
- Medium and large breeds
- >4-6months
- Rx:usually cannot visualise directly. Inferance from OA
17
Q
Which view can be used to highlight the medial coronoid process?
A
Cranial 25-deg lateral / caudomedial view
18
Q
Rx signs of Frag MCP?
A
- Abnormal countour / poor definition
- Medial margin blunted / rounded
- Seperate osseus body
- Joint incongruity / sublux
- Osteophytes (prox margin of anconeal process -> early sign)
- Subchondral bone sclerosis adjacent to trochlear notch / prox radioulnar articulation
- Large osteophyte from medial coronoid margin on CrCa
19
Q
Features of congenital radial head luxation?
A
- Breeds: Bouvier des flandres, Shi Tzy, bulldog, Afghan
- CAUDOLATERAL luxation
- Radial epiphysis may be convex (failure of normal ariticulation)
20
Q
Features of aseptic necrosis of the femoral head?
A
- Young small and toy breeds
- Path: Compromise blood supply - necrosis of subchondral bone, with ongoing cartilage growth. Decreased opacity of femoral head, misshapen.
- Rx: Time dependent
Early: Normal
Later: Linear lucencies in subchondral bone, decreased opacity of femoral epiphysis and metaphysis, flattening / irreg, joint space widening / sublux, PATH FRACT!
21
Q
Features of spontaneous capital physeal fracture of cats
A
- Non-traumatic, delayed physeal closure
- Males, early neutered, approx 2yo
- Rx:
Malalignment of epiphysis and metaphysis
Head / neck osteolysis, sclerosis, resorption
CHECK BILATERALLY -> look for delayed closure
22
Q
What is the most common form of polymelia? Which animals / breeds?
A
- Supernumerary limbs / parts of limbs!
=> Polydactly most common! Cats, and Great Pyrenees
23
Q
Features of nutritional secondary hyperparathyroidism
A
- Calcium deficient or Ca:Phos imbalanced diets -> increased paraT
=> Bone resorption / osteomalacia
- Rx:
Osteopaenia, thin cortices, loss of dental lamina, spinal deformity and FOLDING FRACTURES
24
Q
Features of osteogenesis imperfecta?
A
- RARE, generalised, multisystemic heritable disease
=> structural defect in TYPE 1 collagen
- CS: Stunted growth, muscle atrophy, weakness, pink teeth, PATHOLOGICAL FRACTURES!
Rx: osteopaenia, thin cortices, path fractures, excessively opaque callus, medullary sclerosis
**MAY BE CONFUSED WITH HYPERPARA**
25
List 4 generalised bone disorders
- Nutritional secondary hyperparaT
- Osteogenesis imperfecta
- Panosteitis
- Osteopetrosis
26
Features of panosteitis?
- Self limiting, young large breeds
- MALES 4x more likely
- Breeds: Bassett, GSD, shar pei, giant schnauzer, great pyrenees, mastiff
- 5-12 months, although GSDs as young as 2 mo and old as years!
- NOT INFLAMMATORY strictly
- DIAPHYSEAL, near nutrient foramen
- Rx:
Early: Blurring / accentuation of trabeculae; Nodular opacities within medulla similar to cortical bone -\> Become more diffuse/ homogeneous
Smooth periosteal reaction (33-50% ish)
Late: Opacities resolve -\> coarse thickened bone
- If not responding, consider follow up to rule out other abnormalities
27
What lesion has been described that should not be confused with panosteitis?
- 46% ASYMPTOMATIC NEWFIES
- Metaphyseal lucencies with coarse trabecular bone in distal radius / ulna
28
Features of osteopetrosis? Osteosclerosis?
- RARE inherited metabolic bone disease -\> Abnormal osteoclasts
- Increased bone, specifically in medulla -\> myelophthisic anaemia
- OSTEOSCLEROSIS: Rx identifcal -\> can be seen with nonregen anaemia due to FeLV, possibly paraneoplastic too
Rx: Increased bone opacity, medullary cavities particularly.
Differs from panosteitis -\> not large breed dogs, generalised / involvment of axial skeleton
29
Features of congenital hypoT?
- Rare developmental condition -\> Thyroid aplasia / hypoplasia
- Breeds: cats, boxers, deerhounds, g.schnau, affenpinschers, G.Danes
- DISPROPORTIONATE DWARFISM -\> short limbed, bow legged, long necks and trunks
Rx: EPIPHYSEAL DYSPLASIA - reudced / delayed oss of epiphyses -\> prox tib, humeral and fem condyles; cuboid bone oss. in carpus and tarsus delayed, Short vert bodies and skull.
30
Features of mucopolysaccharidosis?
- Recessive, inherited -\> Defect of glycosaminoglycan catabolism. Multiple types (10+)
=\> Chronic, progressive, systemic disease -\> MS, ocular, neuro, hepat, CV
- Often lame with visual deficits and disproportionate dwarfism / facial dysmorphia
=\> Broad maxilla, widespread eyes, flat nose, short ears, distal joint laxity
Rx: AXIAL AND APPENDICULAR SKELELTON
- Epiphyseal dysplasia -\> Delayed / incomplete epiphyseal ossification. Epiphyses smaller than normal, granular.
- Maxilla short and flattened
- Vert bodies cuboid and short
- Frontal sinuses small / absent
- DJD
- Coxofemoral sublux / lux if femoral head epiphysis affected
31
List 3 examples of epiphyseal dysplasias?
- Congenital hypoT
- Mucopolysaccharoidosis
- Multiple Epiphyseal dysplasia of beagles
32
Features of multiple epiphyseal dysplasia of beagles?
- Rare inherited disorder -\> Failure of normal epiphyseal ossification
- Pseudoachondroplasia of miniature poodles thought to be similar
=\> DELAYED GROWTH, never reach full size
Rx:
- Stippling / irregularity of epiphyses by 3 weeks old
- Most pronounced changes in humeral condyles at 1-3mo
- Also, femur, metacarlap and metatarsal bones, occasionally vertebrae
- EPIPHYSES EVENTUALLY MINERALISE, but deformed
- Hip dysplasia associated
33
List 9 diseases promarily affecting the metaphysis and physis (4 are osteochondral dysplasias!!!)
**Osteochondral dysplasias:**
- Chondrodysplasia of alaskan malamutes
- Chondrodysplasia of Norwegian Elkhounds
- Osteochondrodysplasia of Scottish Fold Cats
- Ocular chondrodysplasia of Labs
**Rickets**
**Hypertrophic osteodystrophy**
**Multiple Cartilagenous Exostosis**
**Retained cartilage core**
**Incomplete ossification of humeral condyle**
34
What are osteochondral dysplasias??
- MULTIPLE, complex. Only a few summarised in text
=\> histologically and biochemically heterogeneous group
- Marked alternations in chondrocyte morphologic characteristcs and cartilage architecture
- Inherited, but variable expression =\> varying severity of CS
- Important to distinguish chondrodystrophoid dogs that have been bred, and sporadic chondrodysplastic dwarfs
35
Features of chondrodysplasia of alaskan Malamutes?
- Autosomal recessive
- Accompanied by MACROCYTIC HAEMOLYTIC ANAEMIA
- CS: Limb shortening, cranial and lateral deviation of forelimbs and enlarged carpi
- Limited to long and cuboidal bones. SKULL AND SPINE SPARED
- Rx:
Most onbvious in sistal ulnar physis and metaphysis
Flaring of distal radial metaphysis
Angular limb deformities due to asynchronous antebrachial growth
- Changes as early as 7 days, more definitive at 5-12 weeks
36
Features of chondrodysplasia of Norwegian Elkhounds?
- Autosomal recessive
- As with other forms of chondrodysp -\> disproportionate dwarfism
- FRONT LIMBS \> HINDLIMBS
- ALSO EFFECTS AXIAL SKELETON
Rx:
Similar long bone changes as per alaskan malamutes
=\> forelimb curvature by 5 weeks
Spinal changes: Lipping and pleating of ventral vert body, delayed union of endplates
Costochondral junctions flared and cupped
Skull UNAFFECTED
37
Features of osteochondrodysplasi of Scottish Folds?
- Simple autosomal dominant
- WITH FOLDING OF THE PINNA!
- CS: Short, difficulty supporting weight, gait abnormalities, thick tail base
- Rx: Evident by. 7weeks
Metaphyses of metatarsals / carpals distorted and physes widened
May effect phalanges too
Punctate lucenceis in carpal and tarsal bones
Caudal vert reduced in length
DJD -\> Ankylosis of carpal or tarsal joints
38
Features of Ocular chondrodysplasia of Labs?
- Autosomal recessive
- Typical skeletal changes + OCULAR MANIFESTATIONS: cataracts, retinal dysplasia, retinal detachment
Rx:
- Long bone shortening, specifically: Ulna and radius
- Delayed growth of anconeal and coronoid processes of ulna, and medial epicondyle of humerus
- Reduced cortical opacity / thickness
- Retained cartilage core (distal ulna)
- Flaring of ulnar metaphysis, widening of growth plate
- Asynchronous Ulna / Radial growth -\> Radius Curvus
- Cuboidal bones and epiphyses misshapen and larger than normal
- Ribs wider than normal -\> flaring at costochondral junction
- Hip dysplasia common
- SKULL AND SPINE SPARED
39
What are the two different forms of hereditary rickets?
Type 1: deficiency of enzyme that converts to active form
Type 2: Anomaly of receptor in target organ
40
Pathophys of Rickets?
- HYPOVITAMINOSIS D
- Inherited or nutritional deficiency
=\> Carnivores derive from diet only (not in skin)
- Insufficient GI absorption of Ca and Phos
- Can lead to secondary hyperparaT as due to lack of Ca -\> mobilisation from skeleton
- CS: Hypocalcaemia, alopecia, lameness (meyaphyseal thickening, bowing / angular limb)
41
Rx features of rickets?
- Widening / flaring of physes
- Cuppining of adjacent epiphyses and metaphyses
- Flared osteochondral junctions of ribs =\> Rachitic rosary
- Diffuse osteopaenia, thin cortices
- FOLDING FRACTURES
42
Pathophys of hypertrophic osteodystrophy?
- Large breeds, young (2-7mo)
- Boxers, G.Danes, Irish setters, Weimaraners...
- Unknown cause: oversupplementation minerals, hypovit C, supparative inflamm without infectious agent, distemper
- CS: pyrexia, d+, footpadd hyperkeratosis, leukocytosis, anaemia, pneumonia...
- Bilaterally symmetric bone lesions, typically distal radius / ulna/ tibia
=\> may effect chostocondral junctions, metacarp/tars, CRANIOMANDIBULAR (?link with CMO)
- Usually self limiting, although -\> possible premature physeal closure and deformity thereafter
43
Rx hypertrophic osteodystrophy
- Double physis sign: lucent zone in metaphysis
- Sclerotic metaphyseal margin - collapse of trabecular bone
- Irregular periosteal new bone around metaphysis
- Soft tissue swelling
- Widening / concavity and increased opacity of distal rib ends
=\> AGGRESSIVE, cannot distinuish from osteomyelitis. Consider follow up + cultures if not improving
44
Features of multiple cartilagenous exostosis?
- Benign proliferative disease (although malig transformation reported)
- Thought to be hereditary
- ANY BONE THAT UNDERGOES ENDOCHONDRAL OSSIFICATION
- OFTEN MULTIPLE BONES
- Usually stop growing once mature, although in cats seems more progressive
- Rx:
Amorpohoous irreegular rib masses
Long bone / vertebral masses more organised
+- absence of cortical bone
Bone may be deformed
45
Features of retained cartilage core?
- Distal ULNAR metaphyses of large dogs. Sometimes lateral femoral condyle
- Disruption of endochondral ossification with retention of hypertrophied cartilage
=\> Angular limb, or seen in normal dogs
Rx:
Cone shaped radiolucency in distal ulnar metaphysis / lateral femoral condyle
Sclerosis around
Angular limb
DJD
46
At what age should the humeral condylar ossification centres fuse?
84 days
47
In IOHC, what is the incidence of Y/T fractures, lateral and medial condylar fracture?
Y/T: 50%
Lateral: 35%
Medial: 15%
48
Pathophys of IOHC
- Spaniel breeds -\> hertitable
- Males
- Condylar fractue with normal exercise
- Bilateral disease freq.
- Incomplete ossification -\> fissure
49
Rx IOHC
- Vertical line midcondylar region
- Craniocaudal or 15 deg oblique
- Smooth periosteal reaction at caudal and lateral aspect
- Path fracture
+- FRAGMENTED MEDIAL CORONOID !
50
Features of flexor enthesopathy / medial epicondylitis
- enthesopathy of flexor tendons -. FLEXOR CARPI ULNARIS
- Close association with ulnar nerve
- CS: none, pain on pronation, chronic mild lameness
- Only evidence of inflammation in acute phase
- Seen +- elbow dysplasia
Rx:
Osseus body adjacent to medial jumeral epicondyle, spur of new bone extending caudally
DJD
+- Elbow dysplasia
51
What is the prevalence of flexor enthesopathy as a primary disease and concomitantly with elbow dysplasia?
Primary: 6%
ED: 34%
