2018 KVMA Orthopedic Radiography 1hr€¦ · •Normal blood supply to femoral head in adult dogs •Synovial membrane (sole supply in puppies) •Arteries in round ligament of the

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Small Animal Orthopedic Radiography

Matthew Paek, VMD, MS, DACVR

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OBJECTIVES

• Basic Approach to Interpretation• Basic Technical Parameters

• Developmental Bone Diseases

• Aggressive vs. Non‐aggressive Bone Diseases

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Approach to Interpretation

•How to read an orthopedic film• Check film imprint label• Evaluate position and exposure• Evaluate soft tissues• Evaluate periosteal margins for new bone formation• Evaluate all corticies and subchondral bone• Evaluate the medullary cavity for changes in opacity. • Evaluate joint capsular attachments• Evaluate joint spaces• Evaluate the periarticular margins• Check the physeal closures in relation to the age of the animal• Stand back evaluate overall alignment and relationship of bones

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Roentgen Signs

•Opacity•Size•Shape•Number

•Location or Position•Margination or Contour

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Radiographic Technique

• Bone•High density•High Z due to Ca & Ph•No motion

• Low kVp technique(<60‐80) improvescontrast

• Positioning: At Least 2Orthogonal Projections!• Oblique projections: carpus/tarsus

• Stressed projections: instability

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Developmental Bone Diseases

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Osteochondrosis (OC/OCD)

•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……

mineralized or… with arthrography

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•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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Osteochondrosis (OC/OCD)

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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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NOT Stifle Osteochondrosis

•Normal anatomy•The extensor fossa of the long digital extensor muscle can be confused with an OC lesion

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OC lesion Extensor fossa

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NOT Stifle Osteochondrosis

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Tarsal Osteochondrosis

•Roentgen signs• Flattening of the medial trochlear ridge of the talus•Widening of the joint space• On the lateral view, the plantar aspect of the tibiotarsal joint will appear wide• Associated with intracapsular ST swelling and DJD

Normal OC

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Tarsal Osteochondrosis

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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 (?)

•Flexor Enthesopathy (?)

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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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•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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•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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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

•Roentgen signs• Irregular, lucent line crossing the anconeal process with adjacent sclerosis• Best seen on flexed lateral view• Secondary osteoarthrosis

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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(aka HOD & Metaphyseal Osteopathy)

•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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•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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•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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•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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•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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•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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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• Caudolateral Curvilinear 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

•Roentgen signs•Periarticular osteophytes form along the acetabular rim, resulting in an irregular edge•Shallow, flattened acetabulum•Inadequate femoral head coverage or even subluxation

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Aseptic Necrosis of the Femoral Head (Legg‐Calve‐Perthes)

•Occurrence and Pathogenesis•Adolescent 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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•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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•Roentgen signs•Deformity and flattening of the femoral head

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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

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

http://devinefarm.net/rp/grp/mpl2.gif

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Medial Patellar Luxation (MPL)

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Aggressive vs. Non‐Aggressive Boney Lesions

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Pattern of Bone Lysis

•Geographic lysis•Large area of lysis•Lesion may appear expansile•Well‐defined with short zone of transition•Nonaggressive or aggressive; however, usually considered least aggressive form of lysis•Bone cysts, multiple myeloma

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Pattern of Bone Lysis• Geographic lysis

Nonaggressive Aggressive 55

Extensive bone loss (30‐60%)required before radiographic changes noted

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•Moth‐eaten lysis•Multiple smaller areas of lysis•These areas may become confluent to form a larger area of lysis•Usually has indistinct margins (long zone of transition)•Usually aggressive• Osteomyelitis or neoplasia

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•Moth‐eaten lysis

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•Permeative lysis•Numerous small or pinpoint areas of lysis•Margins are indistinct (long zone of transition)•Most aggressive pattern• Usually associated with neoplasia

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•Permeative lysis

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Summary of Lytic Patterns

Normal Geographic Moth‐eaten Permeative

Least aggressive Most aggressive

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***Classify based on most aggressive feature!!!***

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Zone of Transition

•Short zone of transition•Abrupt demarcation between normal bone and lesion•Nonaggressive lesions like a bone cyst

•Long zone of transition•Demarcation between lesion and normal bone is less distinct•More aggressive lesions such as osteomyelitis and neoplasia

Demarcation between the lesion and normal adjacent bone

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Type of Periosteal Reaction

•Periosteal reactions•Periosteum composed of two layers;• Inner cambium layer (bone producing)• Outer fibrous layer

•Periosteum is attached to the cortex by Sharpey’s fibers•Periosteal reaction classified in terms of:• Aggressiveness• Activity• Duration

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•Aggressiveness•Classification based on organization of new bone•The more disorganized the new bone formation the more aggressive the lesion

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Less aggressive More aggressive

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•Solid periosteal reaction•Bone completely fills the area under the reaction•The surface can be smooth or undulating•Usually non‐aggressive•Callus

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•Lamellated periosteal reaction• Layered or “onion skin” appearance• Indicates a cyclic or intermittent process•More aggressive than solid, smooth new bone• Stress fracture, osteomyelitis, hypertrophic osteopathy• Transient feature of normal growth (periods of rapid and slow growth)

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•Columnar to spiculatedperiosteal reaction• Can appear like columns of bone (palisading) to spiculated (“sun burst”)• Columnar seen with diseases like hypertrophic osteopathy

• Spiculated seen with primary bone neoplasia like OSA

• Bone incompletely fills the area under the periosteum•More aggressive than lamellated

• Spiculated more aggressive than columnar

66Spiculated Columnar

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•Amorphous periostealreaction• Bone is formed in a disorganized manner

• Process may destroy spicules of bone as they are being formed

• Most aggressive reaction

• Most often neoplastic in origin

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•Codman’s Triangle•Solid periosteal reaction seen at the edge of an aggressive reaction

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•Solid, smooth bone•Callus

•Lamellated• Low grade osteomyelitis

•Columnar (palisading)•Hypertrophic osteopathy•Bacterial osteomyelitis

•Spiculated (sun burst)•Neoplasia or osteomyelitis

•Amorphous•Neoplasia usually

Least aggressive

Most aggressive

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Cortical Disruption

•Processes that destroy corticies are more aggressive than lesions that allow the cortex to remodel or conform to the enlarging mass

Intact Cortex

Disrupted Cortex

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Primary Bone Tumors

•Occurrence•Mostly large and giant breed dogs; no breed predilection•Mean age = 7 years• 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”….aaaand distal tibia

•Chondrosarcoma

•Fibrosarcoma

•Hemangiosarcoma

•Differential diagnoses•Osteomyelitis•Metastatic neoplasia

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Primary Bone Tumors

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Hypertrophic Osteopathy (HO)

•Occurrence•Middle aged to older dogs•Usually due to concurrent thoracic or abdominal disease• 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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•Roentgen signs•Solid, irregular periosteal reaction • Palisading or columnar new bone formation

•Never confined to a single location ‐Usually bilaterally symmetrical and generalized

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•Roentgen signs•Begins on the abaxial surface of the distal metacarpal/metatarsal bones and progresses proximally along the diaphysis•Radiographs of the thorax and abdomen should be obtained to investigate for underlying disease

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Conclusions

•All the previously described skeletal changes fall along a continuum• Some lesions will be clearly nonaggressive or aggressive• A lesion may have features of both• Should be characterized based on the MOST AGGRESSIVE FEATURE

•Generalized or Focal bone lesions• If focal, apply following criteria;

• Location of lesion• Zone of transition• Pattern of lysis• Periosteal reaction• Cortical disruption• Rate of change

• If diagnosis is still unclear…• Repeat radiographs in 10‐14 days•Metastasis check• Bone biopsy or fine needle aspirate

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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•Fever•Lethargy•Anorexia•Lymphadenopathy, etc…

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•Roentgen signs•Variable radiographic appearance• Both lytic and productive changes• Periosteal reaction usually semi‐aggressive• Osteolysis may extend through the cortex• Often sclerosis in adjacent medullary region

•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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Bacterial Osteomyelitis

•Occurrence•Usually secondary to…• Direct inoculation (bite wound, open fracture, or surgery)• Extension from soft tissue injury

•May be hematogenous in young or immunocompromised animals• Hematogenous route is much less common in small animals

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•Roentgen signs•Earliest stage• No bony abnormalities, just soft tissue swelling

•May take 7‐14 days before periostealreaction visible•Periosteal reaction typically solid and extends along shaft of diaphysis; however, can be lamellar to palisading/columnar

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•Nonhematogenous origin• 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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QUESTIONS?

Documents

2018 KVMA Orthopedic Radiography 1hr€¦ · •Normal blood supply to femoral head in adult dogs •Synovial membrane (sole supply in puppies) •Arteries in round ligament of the