Hip Flashcards
What is the definition of hip dysplasia
Abnormal development of the coxofemoral joint resulting in hip laxity Laxity results remodeling Remodeling leads to degeneration
What are the factors that contribute to the expression of hip dysplasia
Etiology is multifactorial
Genetics (polygenic)
-Epigenetics
Environmental (nongenetic)
- body wt
- nutrition
- pelvic muscle mass
Both are necessary Neither is individually sufficient
What is the typical presenting signalment of hip dysplasia?
Large breed dogs
Equal sex distribution (M:F)
Classic biphasic presentation
Young dogs
5-12 months
Laxity
Mature dogs
Highly variable onset/severity
Chronic/recurrent signs
What are the PE and history findings on a patient with hip dysplasia?
History
Exercise intolerance
Bunny hopping gait
Difficulty rising/stiff after rest
Reluctant to climb stairs or jump
May see with ANY bilateral HL lameness
Sits “to the side” – avoiding hip flexion
PE:
Stance
Rear base-wide (compensatory)
Rear base-narrow (degeneration)
Forward weight shift
Gait – “hip sway”
Difficulty rising/sitting
Sits frequently in exam room
Muscle atrophy – quadriceps, biceps
Palpation:
Pain on extension
Young patient
Palpable laxity – subluxate femoral head
Ortolani test or Ortolani “sign”
Mature patient/chronic disease
Decreased ROM in extension
Crepitus
No palpable laxity due to remodeling
What are the gait abnormalities associated with hip dysplasia and their implications?
Stance:
- rear based wided
- rear based narrwo
- forward weight shift
- sits to the side- avoiding hip flexion
Gait:
- hip sway/ model walk
- bunny hopping gait
What is the Orolani sign?
In a young patient
- palpable laxity- subluxate femoral head
Ortolani Test
- requires sedation
- dorsal or lateral recumbency
- hand position: stifle, dorsal to pelvis
push stifle proximally to subluxate
slowly abduct stifle
palpable/audible clunk=positive test
negative in older patients d/t remodeling
Why is Ortolani sign absent in mature dogs?
Remodeling
What is the Ortolani test for?
A positive sign is a distinctive clunk which can be heard and felt as the femoral head relocates anteriorly into the acetabulum. Speficially, this test is for posterior dislocation of the hip
What radiographic view is considered diagnostic for hip dysplasia?
hip extended view with internal rotation of distal limbs
What is this and what does it signify?
Morgan’s line
This is a well-defined linear density between the femoral head and the greater trochanter
represents an early osteophyte
Puppy Line
Indistinct density
Similar location to Morgan’s line
Clinically insignificant
What are the typical radiographic findings of hip dysplasia?
Early
Caudal curvilinear osteophyte (Morgan’s line)
Puppy line – self-limiting, not significant
Subluxation prior to remodeling
Increased joint space
Poor acetabular coverage: ≥ 50% is normal
Femoral neck: coxa valga, thickening
Femoral head: flattening, sclerosis
Osteophytosis, DJD
If hip dysplasia is present in one litter mate, will be in another liter mate to the same degree?
NO! Because you have to have genetic and non-genetic factors!
Generally describe the OFA and it’s limitations and benefits
OFA
generals
- single ventrodorsal pelvis view with hip extended
- 7- point ordinal scale, excellent to severe
CANNOT CERTIFY HIPS BEFORE 24 MONTHS
-positioning underestimates subluxation
Generally describe the PennHip and it’s limitations and benefits
generals:
- distraction applied under anesthesia
- measure the distance of the femoral head to acetabulum center
Lower DI=less laxity
can do at 16 weeks
What are the ideal values?
PennHip= <0.3 is ideal
50% for OFA
What is the medical management for hip dysplasia?
- nutritional management- lower ca/vit. d/energy in a puppy- weight management in adult dog
- excerise modulation
- WEIGHT MANAGMENT IS THE MOST IMPORTANT
Which procedures are considered corrective?
Juvenile Pubic symphiodesis
and triple pelvic osteotomy
Juvenile Pelvic Symphiodesis
Fuse pubic symphysis with cautery- makes pelvis more broad and wide
“Tethers” growth of pelvis
“Rolls” acetabulum ventrally (ventroversion)
Only useful < 20 weeks of age
Assess risk: PennHIP at 16 weeks
If patient is at risk, consider JPS
Relatively noninvasive
Low complication rate
- benefit unlikely after 20 weeks
Triple Pelvic Osteotomy (TPO)
Improve femoral head coverage
Rotate acetabulum dorsally
Indications
Clinical signs of hip dysplasia
Ortolani test – distinct “clunk”
Angle of reduction < 30º
No radiographic evidence of DJD
6-8 months of age (approximately)
Osteotomy of pubis, ischium, ilium
Fixation of ilium with angled plate
Rolls acetabulum dorsally
Allows “capture” of hip
Repositioning of
acetabulum makes
THR challenging
- Case selection very imporant-
- long term function good to excellent
Total Hip replacement
Degenerative joint replaced with prostheses
Femoral stem
Acetabular cup
Timing depends on multiple factors
Generally, delay procedure as much as possible
Skeletal maturity – adequate bone stock
Has been done at 7-8 months of age
Success closely related to experience of surgeon
Cemented and cementless systems
Cemented - seated in PMMA
Cementless
Components coated (hydroxyapatite)
Stability depends upon bony ingrowth into implants
Ideal treatment for large, active dogs
Micro implants available for small dogs, cats
Luxation
Infection
Femur fracture
Loosening
Bone resorption around cement
Failure of ingrowth
Failure => explantation => FHO
Complication rate < 10%
Femoral Head ostectomy(FHO)
Femoral Head and Neck Excision Arthroplasty
Ideally done after skeletal maturity (> 9m)
Conformation of femur, tibia
Stifle abnormalities
Remove entire head and neck of femur
Osteotome, oscillating (sagittal) saw
Femoral Head and Neck Excision Arthroplasty (FHNEA)
Ideally done after skeletal maturity (> 9m)
Pseudarthrosis
Muscles and tendons provide support
Immediate postop limb use essential
ROM and PT exercises encouraged
Conformation of femur, tibia
Stifle abnormalities
Remove entire head and neck of femur
Osteotome, oscillating (sagittal) saw
What are the progonosis of a THR vs FHO?
Total Hip Replacement - $$$$$$
> 90% success
Near-normal to normal function
Complications can be catastrophic
FHO - $$
Long, steady recovery
Smaller patients: virtually normal function
Larger patients: improved comfort/function
What is the most common etiology of coxofemoral luxation?
Trauma
