Hip DysplasiaHip DysplasiaDiagnosis and Classification Diagnosis and Classification

SchemesSchemes

Erica Fields, DVMErica Fields, DVM

Thrall, Textbook of Vet Rad and OhlThrall, Textbook of Vet Rad and Ohlerth, et al. 2000. erth, et al. 2000.

Cause(s) of Hip DysplasiaCause(s) of Hip Dysplasia

MultifactorialMultifactorial– Heritable disorder Heritable disorder – Nutritional factors (overnutrition)Nutritional factors (overnutrition)– Early exercise types/amountsEarly exercise types/amounts– Even season of birth has been shown to Even season of birth has been shown to

affect expressionaffect expression

Thrall. 4th ed Textbook of Vet Rad.Thrall. 4th ed Textbook of Vet Rad. 2002. 2002.

Not Just Dogs…Not Just Dogs…

Yes, we usually associate hip dysplasia Yes, we usually associate hip dysplasia with large, working-breed dogs, BUTwith large, working-breed dogs, BUT

Cats and small or toy breed dogs can Cats and small or toy breed dogs can also be affectedalso be affected

Incidence in DSH estimated at 6.6%, Incidence in DSH estimated at 6.6%, Maine Coons up to 21%Maine Coons up to 21%

Some large breed dogs more susceptible Some large breed dogs more susceptible than others (GSD vs. Greyhound)than others (GSD vs. Greyhound)

WSAVA Congress Proceedings 2002WSAVA Congress Proceedings 2002 and 2005 and 2005

Signs of Hip DysplasiaSigns of Hip Dysplasia

Physical examinationPhysical examination– ““Walking Ortolani”—hands on trochanters Walking Ortolani”—hands on trochanters

during normal walk—palpate for laxityduring normal walk—palpate for laxity– Ortolani sign—dorsal recumbency, abduct Ortolani sign—dorsal recumbency, abduct

hips, feel for “clunk” hips, feel for “clunk” Young dogsYoung dogs– Barden’s Hip Lift—lateral recumbency, Barden’s Hip Lift—lateral recumbency,

anesthetized, lift hip laterally. Greater anesthetized, lift hip laterally. Greater than 5-6 mm movement=positivethan 5-6 mm movement=positive

– Gait abnormalities (swing/bunny hop)Gait abnormalities (swing/bunny hop)

Thrall, 4th ed. Textbook of Vet RadThrall, 4th ed. Textbook of Vet Rad

Signs of Hip Dysplasia Signs of Hip Dysplasia (cont’d)(cont’d)

Radiographic signsRadiographic signs– Joint laxity (distraction index, subluxation)Joint laxity (distraction index, subluxation)– Osteoarthritic changesOsteoarthritic changes

Enthesophytosis at insertion of joint capsule on Enthesophytosis at insertion of joint capsule on caudal aspect of femoral neck (Morgan line)caudal aspect of femoral neck (Morgan line)

OsteophytesOsteophytes Femoral head/neck remodelingFemoral head/neck remodeling Acetabular remodelingAcetabular remodeling Subchondral sclerosis of femoral Subchondral sclerosis of femoral

head/acetabulumhead/acetabulum

Thrall 4th ed Textbook of Vet RadThrall 4th ed Textbook of Vet Rad

What about cats?What about cats?

Coxofemoral subluxationCoxofemoral subluxation Most degenerative changes appear Most degenerative changes appear

on the craniodorsal acetabulum, not on the craniodorsal acetabulum, not the femoral head and neckthe femoral head and neck

Radiographic Detection of Hip Radiographic Detection of Hip DysplasiaDysplasia

MANY methods—each has its advantagesMANY methods—each has its advantages– ““OFA” view—extended hip VDOFA” view—extended hip VD– DAR view—better visualization of acetabular DAR view—better visualization of acetabular

rim bluntingrim blunting– Ultrasonographic evaluationUltrasonographic evaluation– PennHIP distraction methodPennHIP distraction method– European (Federation Cynologique European (Federation Cynologique

International)—five point quality scale International)—five point quality scale numerical system based on 6 factorsnumerical system based on 6 factors

– British (BVA) system—British (BVA) system—– German systemGerman system

www.offa.comwww.offa.com

OFA ClassificationsOFA Classifications

Extended hip VD pelvis viewExtended hip VD pelvis view Consensus of 3 boarded radiologistsConsensus of 3 boarded radiologists Based on evaluation of 9 anatomic Based on evaluation of 9 anatomic

areas (craniolateral acetabular rim, areas (craniolateral acetabular rim, cranial acetabular margin, femoral cranial acetabular margin, femoral head, fovea capitis, acetabular head, fovea capitis, acetabular notch, caudal acetabular rim, dorsal notch, caudal acetabular rim, dorsal acetabular margin, femoral acetabular margin, femoral head/neck junction, trochlear fossa)head/neck junction, trochlear fossa)

Ohlerth, et al. J Sm An Pract 2003. Ohlerth, et al. J Sm An Pract 2003.

OFA guidelines (cont’d)OFA guidelines (cont’d)

Radiographs must be performed Radiographs must be performed after 24 mos of age—based on a after 24 mos of age—based on a study showing that only 16% of study showing that only 16% of dysplastic GSDs were diagnosed at 6 dysplastic GSDs were diagnosed at 6 mos, as compared to 95% at 24 mosmos, as compared to 95% at 24 mos

Six classes—1 through 6 (excellent, Six classes—1 through 6 (excellent, good, fair, borderline, mild, good, fair, borderline, mild, moderate, severe)moderate, severe)

Pros and Cons—OFA Pros and Cons—OFA

ProPro– Easy to perform, no special tools or Easy to perform, no special tools or

certifications neededcertifications needed– Good identification of osteoarthritic Good identification of osteoarthritic

changeschanges– Large centralized databaseLarge centralized database– Well-recognized and established in the Well-recognized and established in the

breeding communitybreeding community– Compares dogs within breedsCompares dogs within breeds

Pros and Cons—OFA Pros and Cons—OFA

ConsCons– Extended hip view may artificially Extended hip view may artificially

tighten joint tighten joint – Not a physiologic positionNot a physiologic position– Selection bias (really bad ones don’t get Selection bias (really bad ones don’t get

submitted)submitted)– Final eval can’t be done before 24 Final eval can’t be done before 24

months—delays breeding timesmonths—delays breeding times– Little eval of laxityLittle eval of laxity

WSAVA World Congress 2002WSAVA World Congress 2002

DAR viewDAR view

Can supplement other views to Can supplement other views to better evaluate changes in dorsal better evaluate changes in dorsal acetabular rimacetabular rim

Used in planning for TPO proceduresUsed in planning for TPO procedures Blunting of DAR caused by Blunting of DAR caused by

microfractures due to altered load microfractures due to altered load bearingbearing

Ohlerth et al. J Sm An Pract. 2003Ohlerth et al. J Sm An Pract. 2003

Ultrasound evaluationUltrasound evaluation

Accepted method in infantsAccepted method in infants In development in dogsIn development in dogs Done with a distraction device in Done with a distraction device in

place, longitudinal view in inguinal place, longitudinal view in inguinal region—dynamic studyregion—dynamic study

Difficult to perform accurately, Difficult to perform accurately, variation may alter measurementsvariation may alter measurements

Only appears to be reliable in Only appears to be reliable in predicting true negativespredicting true negatives

PennHIPPennHIP

Three views—standard OFA view, Three views—standard OFA view, compression view with legs bent at 90 compression view with legs bent at 90 degrees, distraction view with legs bent at degrees, distraction view with legs bent at 90 degrees90 degrees

All radiographs are submitted to central All radiographs are submitted to central databasedatabase

Distraction index calculated based on hip Distraction index calculated based on hip geometrygeometry

Distraction indices correlated to likelihood Distraction indices correlated to likelihood of OA development for various breedsof OA development for various breeds

Thrall 4th ed Textbook of Vet Rad Thrall 4th ed Textbook of Vet Rad

PennHIP—Pros and ConsPennHIP—Pros and Cons

ProsPros– Can be performed as early as 4-5 mos, Can be performed as early as 4-5 mos,

resulting in better breeder screeningresulting in better breeder screening– Anatomic positioning—more functional Anatomic positioning—more functional

evaluation and less artificial joint evaluation and less artificial joint tighteningtightening

– Less selection biasLess selection bias– Evaluates laxity, an early Evaluates laxity, an early

cause/indicator of CHDcause/indicator of CHD

Thrall 4th ed and Ohlerth, et al 200Thrall 4th ed and Ohlerth, et al 20033

PennHIP—Pros and ConsPennHIP—Pros and Cons

ConsCons– Specialized device and training necessarySpecialized device and training necessary– Must submit all radiographs Must submit all radiographs

To get around these disadvantages, some To get around these disadvantages, some people have tried to develop other people have tried to develop other techniques, including using wooden techniques, including using wooden distractors or performing Ortolani and distractors or performing Ortolani and calculating subluxationcalculating subluxation

Ohlerth et al. AJVR 2001Ohlerth et al. AJVR 2001

Federation Cynologique Federation Cynologique Internationale System (FCI)Internationale System (FCI)

Uses 6 criteria that are scored 0-5 (0 Uses 6 criteria that are scored 0-5 (0 good, 5 bad)good, 5 bad)– Norberg angle (more on this later)Norberg angle (more on this later)– Coverage of femoral head by acetabular Coverage of femoral head by acetabular

rimrim– Craniodorsal acetabular rim Craniodorsal acetabular rim

conformation/osteophytosisconformation/osteophytosis– Subchondral bone sclerosis Subchondral bone sclerosis – Femoral head/neck shape and Femoral head/neck shape and

osteophytosisosteophytosis– Joint capsule insertion enthesophytosisJoint capsule insertion enthesophytosis

www.bva.co.uk/publicwww.bva.co.uk/public

British Veterinary British Veterinary AssociationAssociation

12 mos minimum age; no maximum12 mos minimum age; no maximum No resubmissions (unlike OFA, where No resubmissions (unlike OFA, where

prelim eval is allowed)prelim eval is allowed) VD extended hip (OFA) viewVD extended hip (OFA) view Nine criteria evaluated and scored 0-6 Nine criteria evaluated and scored 0-6

PER HIP. Scores for hips are added PER HIP. Scores for hips are added for a total score—best score is 0/worst for a total score—best score is 0/worst is 53 for each hip, or 106 total score.is 53 for each hip, or 106 total score.

Breed mean scores are publishedBreed mean scores are published

www.bva.co.uk/publicwww.bva.co.uk/public

BVA CriteriaBVA Criteria

Norberg angleNorberg angle SubluxationSubluxation Cranial acetabular edgeCranial acetabular edge Dorsal acetabular edgeDorsal acetabular edge Cranial effective acetabular rimCranial effective acetabular rim Acetabular fossaAcetabular fossa Caudal acetabular edgeCaudal acetabular edge Femoral head/neck osteophytosisFemoral head/neck osteophytosis Femoral head remodelingFemoral head remodeling

www.offa.orgwww.offa.org

Comparison of Different Comparison of Different Scoring Systems Scoring Systems

OFA FCI (Euro) BVA (Aust/UK) SV (Ger)OFA FCI (Euro) BVA (Aust/UK) SV (Ger)

E A-1 0-4 (no >3/hip) NormalE A-1 0-4 (no >3/hip) NormalGG A-2 5-10 (no >6/hip) NormalA-2 5-10 (no >6/hip) NormalF B-1F B-1 11-18 Normal 11-18 NormalB B-2 19-25 Fast NormB B-2 19-25 Fast NormM C 26-35 Noch M C 26-35 Noch

ZugelassenZugelassenMod D 36-50 MittlereMod D 36-50 MittlereS E 51-106 SchwereS E 51-106 Schwere

Tomlinson et al AJVR 2000Tomlinson et al AJVR 2000

Norberg AngleNorberg Angle

Used in many evaluation strategiesUsed in many evaluation strategies Evaluation of cranial acetabular Evaluation of cranial acetabular

morphology and subluxationmorphology and subluxation A line is drawn between center points A line is drawn between center points

of both femoral heads and lines drawn of both femoral heads and lines drawn from each femoral head center to the from each femoral head center to the craniolateral aspect of DARcraniolateral aspect of DAR

Angle is calculated between 2 linesAngle is calculated between 2 lines

Tomlinson et al. AJVR 2000Tomlinson et al. AJVR 2000

Norberg AngleNorberg Angle

Traditionally, Norberg angle of greater Traditionally, Norberg angle of greater than 105 degrees and acetabular coverage than 105 degrees and acetabular coverage of greater than 50% is considered normalof greater than 50% is considered normal

A study of 4 most common breeds in OFA A study of 4 most common breeds in OFA registry compared NA, coverage, and OFA registry compared NA, coverage, and OFA classificationclassification

The 105/50 rule does not hold constant The 105/50 rule does not hold constant across breeds. across breeds.

Norberg angles from 92.6 (Goldens) to Norberg angles from 92.6 (Goldens) to 101.9 (Rotties) are correlated with normal 101.9 (Rotties) are correlated with normal OFAOFA

ReferencesReferences Allan G.: Radiographic signs of joint disease. In Thrall, D Allan G.: Radiographic signs of joint disease. In Thrall, D

(ed): Textbook of Veterinary Radiology, 4(ed): Textbook of Veterinary Radiology, 4thth ed. Philadelphia. ed. Philadelphia. WB Saunders Co, 2002. pp 190-195. WB Saunders Co, 2002. pp 190-195.

Ohlerth S, Busato A, Rauch M, Weber U, Lang J. Ohlerth S, Busato A, Rauch M, Weber U, Lang J. Comparison of three distraction methods and conventional Comparison of three distraction methods and conventional radiography for early diagnosis of canine hip dysplasia. radiography for early diagnosis of canine hip dysplasia. Journal of Small Animal Practice. 2003 44:524-529. Journal of Small Animal Practice. 2003 44:524-529.

Ohlerth S, Lang J, Busato A, Gaillard C. Estimation of Ohlerth S, Lang J, Busato A, Gaillard C. Estimation of genetic population variables for six radiographic criteria of genetic population variables for six radiographic criteria of hip dysplasia in a colony of Labrador Retrievers. AJVR hip dysplasia in a colony of Labrador Retrievers. AJVR 2001 62(6): 846-852.2001 62(6): 846-852.

Tomlinson JL, Johnson JC. Quantification of measurement of Tomlinson JL, Johnson JC. Quantification of measurement of femoral head coverage and Norberg angle within and femoral head coverage and Norberg angle within and among four breeds of dogs. AJVR 2000 61(12): 1492-among four breeds of dogs. AJVR 2000 61(12): 1492-1500.1500.

www.bva.co.uk/publicwww.bva.co.uk/public www.offa.orgwww.offa.org