Hips Flashcards
What is the definition of hip dysplasia?
Abnormal development of the coxofemoral joint resulting in hip laxity
- Laxity results in remodeling
- Remodeling leads to degeneration
What are the nongenetic factors that contribute to the expression of hip dysplasia?
- Pelvic muscle mass
- Between breeds–greyhound vs. GSD
- Within breed
- Body weight
- Rapid weight gain predisposes to disease
- Overweight dogs develop OA earlier
- Nutrition
- Dietary Ca/vitamin D
- Restrict
- Energy: restrict
- Dietary Ca/vitamin D
What is the typical presenting signalment of hip dysplasia?
- Large breed dogs
- Equal sex distribution
- Classic biphasic presentation
- Young dogs
- 5-12mo
- Laxity
- Mature dogs
- Highly variable onset/severity
- Chronic/recurrent signs
- Young dogs
What are the PE findings associated with hip dysplasia?
- Stance
- Rear base-wide (compensatory)
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- Rear base-wide (compensatory)
What is the typical history of a patient with hip dysplasia?
- Exercise intolerance
- Bunny hopping gait
- Difficulty rising/stiff after rest
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What is found on palpation of a patient with hip dysplasia?
- 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 is the 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
Why is the Ortolani only done in immature patients?
It is negative in older patients due to remodeling
Which radiographic view is considered diagnostic for hip dysplasia?
VD view of pelvis
Hip extended view
Internal rotation of distal limbs
What do you look for when evaluating radiographs for hip dysplasia?
What is Morgan’s line?
- Well-defined linear density between the femoral head and the greater trochanter
What is the 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
T/F: Hip dysplasia can be expressed very differently among litter mates
TRUE
What are the 2 most common methods for hip dysplasia screening?
Orthopedic foundation for animals (OFA)
PennHIP
Describe the OFA hip dysplasia evaluation
- Single VD pelvis view
- Hips extended
- Stifles internally rotated
- 7-point ordinal scale, excellent to severe
- Cannot certify hips before 2yrs old
- Compliance questionable in NA
- Positioning underestimates subluxation
Describe the PennHIP evaluation for hip dysplasia
- Distraction applied under ax
- Measure distance of the femoral head center to acetabulum center
- DI = distance : radius of femoral head
- Lower DI = less laxity
- DI < 0.3 is ideal
- Does not change after 16wks
- Estimate of risk for OA only, not clinical signs
- Estimate of risk is breed-specific
- Probability of OA
T/F: When treating hip dysplasia you should treat the radiographs, regardless of clinical signs
FALSE
Treat the dog, not the radiographs
What are treatment decisions for hip dysplasia based on?
- Owner compliance
- State of disease (OA present already
- Age of dog
- Responsiveness to treatment (if medical management tried first)
What are the various options for medical management of hip dysplasia?
- Similar to arthritis
- Nutrition management
- Lower Ca/vitD/energy in puppies
- Wt. management in adults
- Exercise modulation
- Physical therapy
- NSAID
- Wt. management most important
What is the difference between corrective and salvage procedures in the treatment of hip dysplasia?
- Corrective
- Take advantage of skeletal immaturity
- Juvenile pubic symphiodesis (JPS)
- Triple pelvic osteotomy (TPO, DPO)
- Salvage–preserve function
- Generally reserved for when medical tx fails
- Femoral head ostectomy (FHO)
- Total hip replacement (THR)
Describe JPS and when it should be used
- Fuse pubic symphysis with cautery
- “Tethers” growth of pelvis
- “Rolls” acetabulum ventrally (ventroversion)
- Only useful < 20wks of age
- Assess risk: PennHIP at 16wks
- If patient is at risk, consider JPS
- Relatively noninvasive
- Low complication rate
What does a TPO do? What are the indications?
- Improve femoral head coverage
- Rotate acetabulum dorsally
- Indications
- Clinical signs of hip dysplasia
- Ortolani test–distinct “clunk”
- Angle of reduction < 30degrees
- No radiographic evidence of DJD
- 6-8mo of age (approximately)
Describe a TPO
- Osteotomy of pubis, ischium, ilium
- Fixation of ilium with angled plate
- Rolls acetabulum dorsally
- Allows “capture” of hip
- Repositioning of acetabulum makes THR challenging
What is the prognosis for corrective procedures for hip dysplasia?
- Less effective for severe laxity (high DI)
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What is done in a THR? What are the indications?
- Total hip replacement
- Degenerative joint replaced with prosthesis
- Femoral stem
- Acetabular cup
- Timing depends on multiple factors
- Generally delayed as long as possible
- Skeletal maturity–adequate bone stock
- Success closely related to surgeon experience
- Ideal for treatment of large, active dogs
- Micro implants available for smaller dogs
What is the difference between cemented and cementless THR systems?
- Cemented–sealed in PMMA
- Cementless
- Components coated (hydroxyapatite)
- Stability depends on bony ingrowth into implants
What is an FHO? When is it indicated?
- Femoral head ostectomy
- Femoral head and neck excision arthroplasty (FHNEA)
- Ideally done after skeletal maturity (> 9mo)
- Conformation of femur, tibia
- Stifle abnormalities
- Remove entire head and neck of femur
- Osteotome, oscillating (sagittal) saw
How does FHO work and what is the recommended post-op care?
- Pseudarthrosis
- Muscles and tendons provide support
- Immediate postop limb use essential
- ROM and PT exercises encouraged
What is the prognosis for salvage procedures in hip dysplasia?
- THR–$$$$$
- > 90% success
- Near-normal to normal function
- Complications can be catastrophic
- FHO–$$
- Long, steady recovery
- Smaller patients: virtually normal function
- Larger patients: improved comfort/function
What is the common etiology of coxofemoral luxation?
- Trauma
- Associated with thoracic injury
- Associated with other fractures
- Treat life-threatening injuries FIRST
What is the difference between craniodorsal and caudoventral luxation?
- Craniodorsal
- Most common (> 90%)
- Pull of gluteal muscles
- Greater trochanter displaced dorsally
- Caudoventral
- Falls or “splits”–excessive abduction of limb
- Femoral head traped ventral to ischium
What are the PE findings of a patient with caudoventral coxofemoral luxation?
- Non-wt. bearing
- Greater trochanter recessed/difficult to palpate
- Leg is held abducted and flexed
- Stifle internally rotated
- Affected limb longer
What are the PE findings in a dog with craniodorsal coxofemoral luxation?
- Affected leg held in relaxed extension
- Foot beneath body, stifle externally rotated
- Affected leg shorter
- Loss of normal triangular relationship
- Pain/crepitus on manipulation/extension
How is hip luxation diagnosed?
- Radiographs
- Rule-out fractures
- Straight line
When is closed reduction of hip displacement not indicated?
Dysplastic hip
Fracture–pelvis or femur
What maneuvers are required following closed reduction of a hip displacement?
- Put joint through ROM to clear debris
- Test stability–if unstable–>open reduction
- Ehmer sling 4-14 days
- Rads
- Confirm reduction
- Confirm reduction following Ehmer placement
- Confirm reduction prior to removing Ehmer
- If reluxated at any point–>open reduction
What coaptation methods are used in craniodorsal luxation vs. caudoventral luxation?
- Craniodorsal
- Ehmer sling
- Abduction
- Internal rotation
- Pushes femoral head away from damaged craniodorsal joint capsule
- Ehmer sling
- Caudoventral
- Hobbles
What are the indications for open reduction of the coxofemoral joint?
- Pelvic/acetabular fracture
- Femoral fractures
- Unstable closed reduction
- Recurrent closed reduction
What are the objecties for open reduction of the coxofemoral joint?
Reconstruct joint capsule and adjacent soft tissues to hold hip in reductino
-OR-
Maintain reduction temporarily with implant until soft tissues heal
(Several procedures often used in combination)
What are the 3 most commonly used procedures for correcting coxofemoral luxation?
- Capsulorrhaphy
- Prosthetic capsule
- Toggle pin
Explain the capsulorrhaphy procedure for treatment of coxofemoral luxation
- Closing the joint capsule torn by trauma
- Heavy gauge suture
- May not be possible in severe cases
- Usually unsufficient as sole repair
What is the prosthetic capsule procedure in the treatment of coxofemoral luxation?
- Drill hole transversely across femoral neck
- Bone screws and washers placed in dorsal acetabulum
- Nonabsorbable, large-diameter suture
- Through femoral bone tunnel
- Around screws in figure 8 pattern
Explain the toggle pin/rod procedure in the treatment of coxofemoral luxation
- Prosthetic capital ligament
- “Toggle” = non-absorbable, large-diameter suture attached to pin or wire
- Toggle placed through medial acetabulum
- Suture material through femoral neck
- Secured on lateral aspect of femur
When are salvage procedures indicated for coxofemoral luxation?
Hip dysplasia
What is the prognosis for coxofemoral luxation?
- Closed reduction
- 50% success rate overall
- More successful if recent injury (< 24hrs)
- Higher with caudoventral luxation
- Lower with dysplasia, other trauma
- Open reduction
- 80-90% success
- Good to excellent limb function
- Expect DJD over time
What is the pathophysiology of Legg-Perthes disease?
- Cause: unknown
- Ischemia to femoral head causes necrosis
- Collapse of epiphysis with loading
- Fragmentation of articular surface
- Revascularization –> new bone
- Malunion of fractured femoral head
- DJD results from incongruent joint
What is the signalment for Legg-Perthes disease?
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What is the typical history/PE findings of a patient with Legg-Perthes disease?
- Signs of hip pain
- Slow onset, progressie: necrosis
- Acute, non-wt.bearing: pathologic fracture
- Chronic remodeling
- Muscle atrophy
- Crepitus
- Decreased ROM
How do you diagnose Legg-Perthes disease?
- Radiographs
- Early changes
- Radiopacity of lateral femoral head
- Focal bony lysis–“motheaten” or “apple core”
- Later changes
- Flattening, mottling of femoral head
- Collapse, thickening of femoral neck
- If rads normal: repeat in 1 mo
- Early changes
Diagnosis?
Legg-Perthes disease
Diagnosis?
Legg-Perthes disease
What is the treatment for Legg-Perthes disease?
- Medical therapy unhelpful
- Femoral head ostectomy
- THR may be considered
- No reason to delay procedure if > 8-9mo
What is the prognosis for Legg-Perthes disease?
What is the aftercare?
- Good prognosis–as for salvage procedure
- Warn owners of risk for contralateral diseae
- Aftercare as for salvage procedure
- Wt. management
- Analgesics
- PT
