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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