Small Animal - University of Minnesota

Small AnimalMusculoskeletalRadiographyJuvenile DisordersKari L. Anderson, DVMCollege of Veterinary MedicineUniversity of MinnesotaOsteochondrosis (OC)• Dysfunction of endochondral ossification• Region of thickened cartilage• May necrose and form cartilage flap• Osteochondritis dissecans (OCD)• Manifestations in the dog– Shoulder– Elbow (condyle, FCP, UME)– Stifle– Tarsus– Retained cartilaginous core– Ununited anconeal processShoulder Osteochondrosis• Male:female ratio of 2.24:1• 4-88 months of age• Large and giant breed dogs• Most common manifestation of OC• Often bilateral disease (50%)Shoulder OsteochondrosisRadiographic findings:• Defect of caudalhumeral head• Subchondral sclerosis• Mineralized flap• Secondary osteoarthritisShoulder OsteochondrosisElbow Osteochondrosis• Males affected more than females• 5-10 months• Large breeds, often retrievers• Second most commonmanifestation• Often bilateral• Part of the elbow dysplasiacomplex

Elbow OsteochondrosisRadiographic findings:• Subchondral defect inmedial condyle• Subchondral sclerosis• Rarely see mineralizedflap• Craniolateral-caudomedial oblique• Secondary osteoarthritisStifle Osteochondrosis• Males affected more thanfemales• 5-77 months• Large breeds – Great Dane,Retrievers, Newfoundlands, , GSD• Least common manifestation• Often bilateralStifle OsteochondrosisRadiographic findings:• Commonly lateralfemoral condyle• Defect or flattening inarticular surface• Subchondral sclerosis• Intracapsular swelling• Mineralized flap• Secondary osteoarthritisTarsal Osteochondrosis• Males and females equallyaffected• 6-12 months• Large breeds – Rottweilers,Labradors• Third most commonmanifestation• 40% bilateralTarsal OsteochondrosisRadiographic findings:• Medial trochlear ridge mostcommon• DP and flexed lateral views• Widening of joint space• Flat or malshapenedtrochlear ridge• Subchondral sclerosis• Caudal mineralized flap• Secondary osteoarthritis• Tibiotarsal swellingRetained CartilaginousCore• OC of the distal ulnar physis• 6-12 months• Large and giant breeds – SaintBernard, Great Dane, Setters• Often incidental• May present with angular limbdeformity

Retained CartilaginousCoreRadiographic findings:• Cone shaped lucency indistal ulnar metaphysis• Smooth and symmetrical inasymptomatic patients• Irregular and asymmetricalin symptomatic patients• Usually bilaterallysymmetricRetained CartilaginousCoreCanine Hip Dysplasia• 5-12 months of age• All breeds affected, also cats• Underlying process is jointlaxity– Leads to abnormal hipdevelopment– Secondary osteoarthritis• May be unilateralRadiographic Evaluationof HipsExtended limb VD view:• Used by OFA• Limbs extended and parallel• Patellas superimposed onmidline• Femurs cross ischiatictuberosity equally• Wings of ilia and obturatorforamina symmetricRadiographic Evaluationof HipsPennHIPPennHIP:• Distraction/compressiontechnique• Quantitative measurement ofpassive hip laxity – DI• Probability of developing hipdysplasia directly related to DI• Three views: distraction,compression, extended limbVD

Radiographic Evaluationof HipsNordberg angle:• Measurement made fromextended limb VD – numberrepresents laxity• Normal ≥ 105º• Abnormal ≤ 90º• Borderline 90º to 105ºCanine Hip DysplasiaNormal Radiographic findings:• Deep cup-shapedacetabulum• Smooth circular margin offemoral head• >2/3 of head within dorsalrim• Parallel joint space• Narrow femoral neckCanine Hip DysplasiaCanine Hip DysplasiaAbnormal Radiographic findings:• Shallow acetabulum• Flattening of femoral head• Subluxation of hip• Thickened femoral necks• Subchondral sclerosis• Secondary osteoarthritisCanine Hip DysplasiaCanine Hip Dysplasia

Fragmented Medial CoronoidProcessUnunited AnconealProcess• Males affected twice as often• 5-12 months of age• Large breeds – GSD• Normal anconeal process fuses by5 months• May be bilateral (20-35%)Ununited AnconealProcessRadiographic findings:• Radiolucent lineseparating the anconealprocess from theolecranon after 20 wks• Line generally irregularand of variable width• Ends sclerotic, secondaryosteoarthritis• Flexed lateralOFA Evaluation of ElbowDysplasia• Must be 2 years of age• Extreme flexed lateral views• No grading for non-dysplasticelbows• Dysplastic classification:– Grade I – min bone formation (5 mm)Panosteitis• Males affected four times moreoften• 5-12 months• Large and giant breeds – GSD,Great Danes, Dobermans, Retrievers,Basset hounds• Self-limitinglimiting dz affecting longbones• Not an inflammatory processPanosteitisRadiographic findings:• Early blurring and accentuation oftrabecular bone• Diminished cortico-medullarydefinition• Patchy, nodular medullaryopacities• Smooth periosteal new bone• Eventual normal remodeling

PanosteitisHypertrophic Osteodystrophy(HOD)• 2-66 months of age• Large and giant breeds – GreatDane, boxer, GSD, weimaraner• Self-limitinglimiting dz of metaphyses oflong bones• Neutrophilic inflammatoryresponse with necrosis,hemorrhage, osteoclastsHypertrophic Osteodystrophy(HOD)Radiographic findings:• Radiolucent lines inmetaphyses, parallel andadjacent to physis• Metaphyseal flaring andsclerosis• Periosteal “cuffing”• Soft tissue swelling• Premature closure of physismay occurHypertrophic Osteodystrophy(HOD)Legg-CalvCalvé-PerthesDisease• AKA: aseptic necrosis of thefemoral head• 4-10 months of age• Toy and small breeds – Yorkies,Toy Poodles, Poms, , Chihuahua,terriers, Pug, Dachshund• Usually unilateralLegg-CalvCalvé-PerthesDiseaseRadiographic findings:• Radiolucencies insubchondral bone• Decreased opacity in femoralepiphysis and metaphysis• Flattening of head• Remodeling of acetabulum• Secondary osteoarthritis

Feline SyndromePatellar Luxation• Young and immature dogs• Toy and miniature breeds, but also largebreeds• Congenital or developmental deformities ofrear limbs predispose to patellar luxation– Abnormal femoral neck angles– Lateral bowing of femur– Hypoplastic medial femoral condyle– Rotation of tibial tuberosity– Shallow trochlear groove• May be traumatic with concurrent cruciatedzPatellar LuxationPatellar LuxationRadiographic findings:• Often don’t t appreciate on radiographs• Include hip, femur, proximal tibia• May see patella superimposed overfemoral trochlea• May see secondary osteoarthritisGrowth Plate Injuries• Skeletally immature patients• Trauma is the most common cause,other causes include HOD, retainedcartilaginous core, chondrodysplasias• Any physis, but most clinicallysignificant in distal antebrachium• Secondary angular limb deformitiesGrowth Plate Injuries• Salter Harris fractures:– Type I: physeal– Type II: physeal-metaphyseal– Type III: physeal-epiphysealepiphyseal– Type IV: physeal-epiphysealepiphyseal-metaphyseal– Type V: compression physeal– Type VI: eccentric physeal impactionresulting in transphyseal bridging

Growth Plate InjuriesRadiographic findings:• Affected physis may or may notappear closed• May be affected entirely orpartially• Radiograph both limbs• Secondary angular limbdeformities and jointincongruenciesGrowth Plate InjuriesPremature closure of distal ulna:• Partial or complete physealclosure• Shortened ulna• Cranial and medial bowing ofradius• Carpal valgus• Humero-ulnarulnar jointsubluxation• Secondary osteoarthritisGrowth Plate InjuriesGrowth Plate InjuriesPremature closure of distal radius:• Partial or complete closure of physis• Shortened radius• Humero-radial radial subluxation• May see fragmented medial coronoid• Secondary osteoarthritis