Transcript Bone Response to Disease VM855 Orthopedics Lecture 1

Small Animal Orthopedic Radiology
Lecture 3 –
Acquired Bone Diseases
Fracture Healing and Evaluation
VCA 341 Fall 2011
Andrea Matthews, DVM, Dip ACVR
Assistant Professor of Radiology
Hypertrophic Osteopathy (HO)
Occurrence
 Middle aged to older dogs
 Usually due to concurrent thoracic or abdominal
disease
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Often pulmonary neoplasia; also reported with
pulmonary abscesses, bronchopneumonia, bacterial
endocarditis, heartworm disease, esophageal
pathology, as well as hepatic and bladder neoplasia
 Gradual or occasional acute onset in lameness
 Animal reluctant to move
 Symmetric, non-edematous, firm swelling of the
distal limbs
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Hypertrophic Osteopathy (HO)
Roentgen signs
 Solid, irregular periosteal reaction
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Palisading or columnar new bone
formation
 Never confined to a single location
- Usually bilaterally symmetrical
and generalized
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Hypertrophic Osteopathy (HO)
Roentgen signs
 Begins on the abaxial surface of the 2nd and
5th metacarpal/metatarsal bones and
progresses proximally
 Spares the small bones of the carpus and
tarsus
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But is seen on the accessory carpal bone and
calcaneus
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Hypertrophic Osteopathy (HO)
 Location of periosteal reaction is diaphysis
of tubular bones
Radiographs of the thorax and abdomen
should be obtained to investigate for
underlying disease
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Fungal Osteomyelitis
Occurrence
 Typically seen in young to middle-aged dogs
 May be seen in any breed; however, more
common large breeds such as working or sporting
breeds
Usually hematogenous in origin
Often systemically ill
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Fever
Lethargy
Anorexia
Lymphadenopathy, etc…
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Fungal Osteomyelitis
Roentgen signs
 Variable radiographic appearance
• Both lytic and productive changes
• Periosteal reaction usually semi-aggressive
• Osteolysis may extend through the cortex
 Usually in the metaphyseal region of long bones
• May be joint involvement with extensive bone destruction
 Often polyostotic but can be monostotic
Differential Diagnoses
 Primary bone tumors
 Metastatic bone tumors
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Fungal Osteomyelitis
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Fungal Osteomyelitis and arthritis
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Bacterial Osteomyelitis
Occurrence
 Usually secondary to…
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Direct inoculation (bite wound, open fracture, or
surgery)
Extension from soft tissue injury
 May be hematogenous in young or
immunocompromised animals
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Hematogenous route is much less common in small
animals
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Bacterial Osteomyelitis
Roentgen signs
 Earliest stage
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No bony abnormalities, just soft
tissue swelling
 May take 7-14 days before periosteal
reaction visible
 Periosteal reaction typically solid and
extends along shaft of diaphysis;
however, can be lamellar to
palisading/columnar
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Bacterial Osteomyelitis
Nonhematogenous origin
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Lesion location depends on affected area
May affect multiple bones in the same limb
Lucencies around surgical implants
May see draining tract from surgical implant or foreign
body
Hematogenous origin
 Metaphyseal due to extensive capillary network
 Often multiple limbs affected (polyostotic)
Differential Diagnoses
 Healing fracture
 Primary or metastatic bone tumor
 Fungal osteomyelitis
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Bacterial Osteomyelitis
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Primary Bone Tumors
Occurrence
 Mostly large and giant breed dogs; no breed
predilection
 Mean age = 7 years
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Bimodal distribution seen in animals as young as
6 months
 Slightly more common in male dogs
 May be associated with a previous fracture or
metallic implant
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Primary Bone Tumors
Roentgen signs
 Radiographic appearance is variable
• Primarily osteoblastic
• Primarily osteolytic
• Combination of both
 Lytic and/or productive changes are
aggressive in nature
 Typically monostotic
 Located often in metaphyseal region of a
long bone
 Does not typically cross the joint
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Primary Bone Tumors
Osteosarcoma
 Most common primary bone tumor (>85%)
 “Away from the elbow, toward the knee”
Chondrosarcoma
Fibrosarcoma
Hemangiosarcoma
Differential diagnoses
 Osteomyelitis
 Metastatic neoplasia
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Primary Bone Tumors
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Fracture Evaluation and
Bone Healing
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Fracture Evaluation
Initial radiographs
 Two orthogonal views (90o to one another)
 Include the joint proximal and distal to the fracture
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Determine joint involvement
 Special radiographic views may be necessary to
determine the extent of the fracture
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Oblique, etc
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Fracture Recognition
Most are visible as abnormal
radiolucent lines
 Some may not be as obvious
 Ex. Compression, non-displaced or
pathologic fracture
 Occassionally, compression
fractures may result in alteration in
size or opacity, creating a
summation opacity (more opaque
than normal)
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Fracture Recognition
Non-displaced fractures
 May not be seen initially
 Seen days later when resorption of
bone at fracture margins has
occurred
 Some are recognized by presence
of bony callus
 If clinical suspicion of fracture is
high but equivocal  Nuclear
medicine
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Fracture Description
Fracture types
 Open vs closed
 Incomplete vs complete
 Simple vs complex/comminuted
 Transverse, oblique or spiral
 Extra-articular, articular,
compression, avulsion
 Displaced vs. non-displaced
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Bone Healing
Primary bone healing
 Occurs with rigid internal fixation
 Results in bony union through direct
growth of haversian system across
the fracture
 Minimal to no bony callus
 Cannot occur across a fracture gap
 Usually occurs with compression
plate reduction
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Primary Bone Healing
Radiographic signs of primary bone
union
 Lack of callus
 Gradual loss in opacity of fracture
ends
 Progressive disappearance of
fracture line
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Bone Healing
Secondary bone healing
 Lack of rigid internal fixation
Most common type of fracture
healing in small animals
and excellent anatomic
reduction
 Bone heals through initial
deposition of fibrous tissue
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Callus formed by series of
maturations
Granulation tissue 
cartilage  mineralized
cartilage  replaced by
bone
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Secondary Bone Healing
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Secondary Bone Healing
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Bone Healing
Factors that affect bone healing
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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
And on and on and on…
 Age, breed, species
 Presence of systemic disease
 Steroid administration
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Initial Postoperative Evaluation
Evaluate;
 Fracture alignment
 Degree of fracture reduction
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Needs to be at least 50% reduction of fracture
margins
 Presence of joint incongruities
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Step deformities
If fracture is articular
 Rotation of fracture fragments
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Initial Postoperative Evaluation
Evaluate;
 Placement of fixation devices
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With bone plate, ideally want 6 corticies engaged
with cortical screws above and below the fracture
site
Pins of external fixator should be angled 65-70o to
bone
 Not possible with all types of external fixators
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Cerclage wires should be of adequate size, be
perpendicular to the long axis of the bone, be a
minimum of 1 cm apart, be adequate in number and
fit snugly against the cortex
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Growth Plate Injuries
Good
prognosis
Poorer prognosis
Guarded
prognosis
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Growth Plate Injuries
Occurrence
 Etiologies
• Trauma
• Severe hypertrophic osteodystrophy (HOD)
• Retained cartilaginous core
 Skeletally immature animals <1 year
 Prognosis
• Salter Harris Type I and II have better prognosis
• Type III and IV have poorer prognosis due to
disturbance of resting cell layer
• Type V have guarded prognosis due to damage of
proliferative zone
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Growth Plate Injuries
Roentgen signs
 Unilateral or bilateral
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Radiographs both limbs for comparison
 Affected physis may initially appear normal or may
be closed
 Skeletal deformities
 Distal ulnar physis is commonly affected due to
shape
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Often type V
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Premature Distal Ulnar Physis Closure
Roentgen signs
 Affected ulna is measurably
shorter than contralateral side
(unless bilateral)
 Styloid process of ulna may be
separated from carpus
 May have cranial and/or medial
bowing of radius
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Cortical thickening of the concave
side of the radius (due to stress
remodeling)
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Premature Distal Ulnar Physis Closure
Roentgen signs
 Distal radius is subluxated
craniomedially from the radiocarpal
bone
 Manus deviates laterally
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Carpal valgus
 Humero-ulnar joint space may be
widened (subluxation)
 +/- osteoarthrosis
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Premature Distal Ulnar Physis Closure
 Note widening of the
humero-ulnar joint
(black arrows)
 Note the UAP that
can occur
secondarily (green
arrow)
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Premature Distal Radial Physis Closure
Roentgen signs
 Shortened length of the radius compared to
contralateral side (unless bilateral)
 Increased radiocarpal joint space
 Increased humero-radial joint space (subluxation)
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Growth Plate Injuries
The elbow is key to determine origin of slowed growth
Normal
Radial physeal
closure
Ulnar physeal
closure
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Premature Distal Ulnar Physis Closure
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Premature Distal Radial Physis Closure
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End
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