small animal orthopedic radiology lecture 2 – developmental bone disease vca 341 fall 2011 andrea...
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Small Animal Orthopedic Radiology
Lecture 2 – Developmental Bone Disease
VCA 341 Fall 2011
Andrea Matthews, DVM, Dip ACVR Assistant Professor of Radiology
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Osteochondrosis
Failure of endochondral ossification Leads to increased thickness of articular cartilage Appears as subchondral defect
Osteochondrosis = OC
Osteochondritis dissecans = OCD When a flap is formed and separates from subchondral
bone Only seen radiographically when……
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mineralized or… with arthrography
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Osteochondrosis
Occurrence Young, rapidly growing, large to giant breed dogs Usually develop signs between 6-9 months of age Occurs in specific anatomic locations
• Caudal aspect of humeral head
• Medial aspect of the humeral condyle
• Lateral femoral condyle
• Trochlear ridges of the talus (medial most commonly)
Can occur in other locations Frequently bilateral
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Shoulder Osteochondrosis
Roentgen signs Subchondral defect and scelosis of the caudal or
caudolateral aspect of the humeral head
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Shoulder Osteochondrosis
Roentgen signs Secondary osteoarthrosis Osteophytes may form in the intertubecular groove Calcified flap of articular cartilage OCD
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Elbow Osteochondrosis
Roentgen signs Subchondral defect and sclerosis of the medial aspect
of the humeral condyle, best seen on DLPMO view Secondary osteoarthrosis
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Stifle Osteochondrosis
Roentgen signs Subchondral defect and sclerosis of the distal aspect of
the lateral femoral condyle May also affect medial condyle but less common Joint effusion and osteoarthrosis
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Stifle Osteochondrosis
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Stifle Osteochondrosis
Normal anatomy The extensor fossa of the long digital extensor muscle
can be confused with an OC lesion
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Stifle Osteochondrosis
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OC lesion Extensor fossa
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Tarsal Osteochondrosis
Roentgen signs Flattening of the medial trochlear ridge of the talus Widening of the joint space Associated with intracapsular ST swelling and DJD
11Normal OC
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Tarsal Osteochondrosis
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Tarsal Osteochondrosis
Roentgen signs On the lateral view, the plantar aspect of
the tibiotarsal joint will appear wide A mineral fragment may be seen OCD
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Elbow Dysplasia
Fragmented medial coronoid process (FCP)
Ununited anconeal process (UAP)
Osteochondrosis of the medial humeral condyle (OC)
Asynchronous growth of the radius and ulna (?)
Proximal ulnar dysplasia (?)
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Fragmented Medial Coronoid Process
Occurrence Most common developmental abnormality of the elbow Medium and large breed dogs
• Retrievers, GSD, Bernese Mountain Dog Clinical signs develop usually at 5-12 months of age Higher incidence in males
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Fragmented Medial Coronoid Process
Roentgen signs Earliest signs are sclerosis of the trochlear notch of the
ulna and osteophytes on the anconeal process and radial head
Osteophytes on the medial coronoid seen on the craniocaudal view
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Fragmented Medial Coronoid Process
Roentgen signs Medial coronoid appears blunted on the lateral views May see fragment; however, no fragment is visualized
in the majority of cases
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Fragmented Medial Coronoid Process
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Ununited Anconeal Process
Occurrence Anconeal process forms from separate center of
ossification Normally fuses to proximal ulna at 5 months of age Failure to fuse (likely due to joint incongruity) UAP GSD predisposed; also seen in other large breeds and
Bassett hounds
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Ununited Anconeal Process
Roentgen signs Irregular, lucent line crossing the anconeal process with
adjacent sclerosis Best seen on flexed lateral view Secondary osteoarthrosis
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Ununited Anconeal Process
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Ununited Anconeal Process
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Panosteitis
Occurrence 5-18 months of age; reports in mature animals (out to 7
years) Large to giant breed dogs
• GSD, Dobermans, Retrievers, Bassett hounds Self limiting disease with unknown etiology Shifting leg lameness with pain on palpation of long
bones Histologically no evidence of inflammation
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Panosteitis
Roentgen signs
Early Increased medullary opacity Usually in diaphysis near nutrient foramen Blurring of trabecular pattern
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Panosteitis
Roentgen signs
Late Medullary opacities become better
delineated patchy appearance of medullary cavity
Adjacent opacities may coalesce Rough endosteal surface Solid periosteal reaction may be noted
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Panosteitis
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Hypertrophic Osteodystrophy (HOD)
Occurrence 2-7 months of age Large to giant breeds of dog Unknown etiology Usually systemically ill
• Usually reluctant to move, painful walking
• Swollen, painful distal radius/ulna and distal tibia
• Pyrexia
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Hypertrophic Osteodystrophy (HOD)
Roentgen signs Lesions usually bilaterally symmetric
and involve the metaphysis of long bones, especially the distal radius, ulna and tibia
Early Thin, radiolucent band in the
metaphysis just proximal to the physis “double physis sign”
Sclerosis adjacent to the radiolucent line in the metaphysis
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Hypertrophic Osteodystrophy (HOD)
Roentgen signs
Late Formation of a cuff or sleeve of
periosteal new bone adjacent to the metaphysis, which is separated from cortex by thin, lucent zone
Represents subperiosteal hemorrhage
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Hypertrophic Osteodystrophy (HOD)
Roentgen signs
Late Periosteal reaction becomes more
solid and confluent with the cortex later on
Results in marked bony enlargement of the metaphysis
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Hypertrophic Osteodystrophy (HOD)
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Hypertrophic Osteodystrophy (HOD)
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Hypertrophic Osteodystrophy (HOD)
Images show progression of disease…
Early Late
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Retained Cartilaginous Core
Occurrence Unknown etiology Form of OC of the distal ulnar
metaphysis/physis• Failure of endochondral ossification
resulting in formation of core of cartilage in the metaphysis
Large to giant breeds• Saint Bernard
Usually develop clinical signs around 6-12 months of age
Often bilateral
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Retained Cartilaginous Core
Roentgen signs Conical, radiolucent zone extending from the distal ulnar physis
proximally into the distal ulnar metaphysis Smoothly marginated or irregular
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Retained Cartilaginous Core
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Retained Cartilaginous Core
Roentgen signs Can cause asynchronous growth of
the radius and ulna and angular limb deformity
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Hip Dysplasia
Normal hip joint At least ½ of the femoral head
should be covered by the dorsal acetabular rim
The femoral neck should be narrower than the head and have a smooth margin
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Hip Dysplasia
Roentgen signs Shallow, flattened acetabulum Inadequate femoral head coverage or even subluxation
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Normal
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Hip Dysplasia
Roentgen signs Periarticular osteophytes form along the acetabular rim,
resulting in an irregular edge
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Hip Dysplasia
Roentgen signs Morgan line
• Osteophyte formation along caudal femoral neck usually secondary to joint laxity
• These osteophytes are actually enthesiophytes at the attachment of the joint capsule
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Hip Dysplasia
Standard VD view of Pelvis Pull legs straight back and rotate
inward Open collimation to include entire
pelvis and both femora through to the stifles
Called “straight or extended leg view” Used for OFA evaluation
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Hip Dysplasia
Orthopedic Foundation for Animals (OFA) Uses extended leg view 24 months of age or older Evaluate for subluxation, degenerative changes Hips graded based on following categories
• Excellent• Good• Fair• Borderline• Mild dysplasia• Moderate dysplasia• Severe dysplasia
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Hip Dysplasia
PennHIP The University of Pennsylvania Hip Improvement Program Allows evaluation of joint laxity prior to degenerative
changes Examiners have to be certified Three sets of radiographs
• Extended leg
• Distraction view with distraction apparatus
• Compression view with distraction apparatus Calculation of distraction index (DI)
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Hip Dysplasia
Distraction index (DI) 0 = tightest hip 1 = completely luxated hip 0.4 = cut off index which identifies
dogs that have the highest probability of developing osteoarthrosis secondary to hip dysplasia
Index corrected for breed
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Hip Dysplasia
Extended leg
CompressionDistraction
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Hip Dysplasia
Other methods Half-axial view
• Distraction method
• Distance between the femoral heads compared on extended leg view and distraction view
Norberg angle
• Used in Europe
• Normal angle is >105 degress
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Aseptic Necrosis of the Femoral Head (Legg-Calve-Perthes)
Occurrence and Pathogenesis Young (8-18 months of age) toy and small breed dogs
• Poodles, miniature pinscher, terriers Bilateral <15% of the time Compromised blood supply to proximal femoral
epiphysis necrosis of subchondral bone Normal blood supply to femoral head in adult dogs
• Synovial membrane (sole supply in puppies)
• Arteries in round ligament of the head of the femur
• Nutrient vessels through metaphysis (after physeal closure)
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Roentgen signs Increased width of joint space
• Articular cartilage thickens as ischemia causes necrosis of subchondral bone
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Aseptic Necrosis of the Femoral Head (Legg-Calve-Perthes)
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Roentgen signs Irregular opacities in the
femoral head
• Fragmentation of trabeculae Patchy regions of osteolysis in
femoral head
• Invasion of vascular granulation tissue absorbing and replacing dead bone
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Aseptic Necrosis of the Femoral Head (Legg-Calve-Perthes)
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Roentgen signs Deformity and flattening of the femoral head
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Aseptic Necrosis of the Femoral Head (Legg-Calve-Perthes)
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Roentgen signs Remodeling of the acetabulum = osteoarthrosis Due to abnormal articulation and osteophyte formation
on the acetabulum, femoral head and neck
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Aseptic Necrosis of the Femoral Head (Legg-Calve-Perthes)
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Patellar Luxation (PL)
Occurrence Young, small breed dogs; also
seen in large breeds• Medial luxation in small
breeds• Lateral in large breeds
Most commonly congenital/developmental• Can be traumatic
Associated with malalignment of the quadriceps due to rotation and/or deformity of the femur and/or tibia
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http://devinefarm.net/rp/grp/mpl2.gif
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Medial Patellar Luxation (MPL)
Roentgen signs Patella medial to trochlear groove Coxa vara
• Lateral bowing of distal femur
• Medial bowing of the proximal tibia
• Medially located tibial tuberosity and quadriceps
Shallow trochlear groove
• Requires skyline view to evaluate Secondary osteoarthrosis usually mild
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http://devinefarm.net/rp/grp/mpl2.gif
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Medial Patellar Luxation (MPL)
Arrow is pointing to cranial margin of the patella
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End
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