Lecture 4: Surgery of the Hip 1 (Exam 1) Flashcards
What is canine hip dysplasia (CHD)
A Hereditary dev condition of the coxofemoreal (hip) joint that leads to degenerative joint disease (DJD)
What is the most prevalent genetic based ortho disease of dogs
Canine Hip Dysplasia (CHD)
Define hip dysplasia
Abnorm dev of hip joint characterized by subluxation or complete luxation of the femoral head in younger px & mild to severe DJD in older px (Hip laxity!)
What can be found w/ DJD
- Cartilage damage
- Osteophyte formation
- Subchondral sclerosis
Define luxation of the hip joint
Complete separation btw/ the femoral head & acetabulum
Define subluxation
Partial or incomplete separation btw/ femoral head & acetabulum
What cause hip dysplasia pain in juvenile dogs
- Articular cartilage wear exposes pain fibers in the subchondral bone
- Laxity causes stretching of soft tissue
What causes hip dysplasia pain in older dogs
Osteoarthritis
Describe the clinical signs in canine hip dysplasia
- Exercise intolerance is the most common sign
- Clinical signs often don’t correlate w/ radiographic findings
- Some dogs w/ mod or severe dysplasia are asymptomatic
Describe the etiopathogenesis of hip displasia
- Hereditary: polygenetic multifactoral
- Envi influenced
- Hips are norm at birth
What will reduce onset, severity, & incidences of CHD
Restricting growth rate
T/F: CHD can be reduced & eliminated by breeding only dogs w/ norm hips
False; it is only reduced & not eleiminated
Describe the signalment of CHD
- Sometimes seen in toy breeds & cats (bony changes rare)
- Highest incidence in large breed dogs
- Rapid weight gain & growth causes probs w/ dev of supporting soft tissue which contributes to hip laxity
Describe hip laxity
- Decreases SA of articulation (concentrating stress over a smaller area)
- Favors the dev of CHD
What are the physiologic responses to laxity
- Increased joint fluid vol
- Proliferative fibroplasia of joint capsules
- Increased trabecular bone thickness
What is the mechanical response to laxity
- Joint capsule stretching
- Acetabular bone deformation
- Periosteal nerve tearing
- Sharpey’s fibers rupture, bleed, & form osteophytes
- Microfractures of acetabular trabecular cancellous bone
What structures act together to support the hip
- Round ligament
- Joint capsule
- Periarticular musculature
- Capsular hydrostatic constraints
What are the clinical sx in young dogs (4 - 12 M)
- Most often: sudden onset of unilateral lamenes
- Abnorm gait (swaying, short stride, or bunny hopping)
- Pain
- Poor muscle dev in the hind limbs
- Joint laxity
- Positive ortolani sign
what is the angle of reduction
Point where femoral head slips back into the acetabulum when abducted
What is the angle of subluxation
Point where the femoral head slips out of the acetabulum when adducted
What are the clinical signs in adult dogs ( > 15 M)
- Chronic lameness that is worse after exercise
- Often bilateral lameness
- Decreased muscle mass in pelvic limbs
- Waddling gait/bunny hopping
- Crepitus & pain on palpation
- Rises slowly w/ difficulty
- Shoulder muscle hypertrophy
- Difficulty climbing stairs
What can be found in both a young dog & older dog differential dx
Cranial cruciate injury
What is a major sign of laxity in the PE of young dogs
- Barlow test (first part of ortolani test subluxation)
- Positive ortolani sign (reduction of the femoral head)
Which organizations say radiography is req for definitive dx
- Ortho foundation of animals (OFA)
- Univ of Pennsylvania Hip Improvement Program (PennHIP)
What does radiography eval
- Sublux/lux
- Acetabular margin
- Size, shape, & architecture of femoral head & neck
- Presence of exostosis or osteophytes
- Subchondral bone eburnation
What does the OFA do
- Collate & disseminate info on ortho dx of animals
- Advise, encourage, & establish control programs to lower disease incidence
- Encourage & finance research
- Receive fund & make grants
Describe the OFA: dysplasia control registry
- 24 M or older to register
- Positioning specific VD radiograph (Hip extended view)
- Film ID req
- Evaluated indep by 3 radiologist based on breed, sex, & age
- Consensus repor produced
What are the 7 grades of the OFA consensus report
- Excellent hip conformation
- Good h8ip conformation
- Fair hip conformation
- Near normal
- Mild hip dysplasia
- Mod hip dysplasia
- Severe hip dysplasia
How is the px positioned for a VD radiograph
- Extend the hips & internally rotate the tibias (patellas are directly over the trochlear grooves)
- Be sure the pelvis is straight (the obturator foramina are symmetric)
When is a px a candidate for total hip replacement (THR) or femoral head ostectomy (FHO)
If clinical signs cannot be managed medically
List the criticisms of the OFA
- test non physiologic hip position
- Joint laxity is dynamic
- Subjective/intra & inter observer variation
- Influence of age on reliability
- Variation in ax
- Hormonal effects on hip laxity
- Variation w/ health status of dog
- Lack of uniform reporiting
What is PennHIP
- Stress radiographic dx method
- Database/registry
- International network of hip eval centers
Describe the PennHIP measures max passive hip laxity
- Passive vs. functional laxity
- Shows ~ 2.5x > laxity than seen on the hip extended view
- Statistically predictive @ 16 W of age
- Distraction view very reliable to show laxity (highly repeatable & objective; has a distraction index
Describe the PennHIP radiographic procedure
- Hip extended radiograph - the hind legs are placed in “extension.” Used to ID radiographic signs of hip osteoarthritis (OA)
- Compression radiograph - hip placed in neutral stance position & the femoral heads are seated in the acetabula
- Distraction radiograph - hips are places in the same neutral position as compression radiograph; a special device called a distractor is used to reveal the joint laxity
Label these steps of a PennHIP readiographic procedure
What is the PennHIP distraction index (DI)
- DI = measure of hip laxity (distance the ball is distracted from the hip socket
- Expressed as a # btw/ 0 & 1
What does a DI near 0 =
little joint laxity (very tight hips)
What does a DI closer to 1 =
High degree of laxity (very loose hips)
Dogs w/ (tighter/looser) hips are less likely to develop hip dysplasia than dogs w/ (tighter/looser) hips
tighter;looser
What does a level below of 0.30 mean
Below .30 hip dysplasia is very unlikely to occur
What are the vet req in PennHIP
- Training
- Certification
- Mandatory submission of ALL films
- Encourage positive ID (microchip or tattoo)
What are the criticisms of PennHIP
- Training req time & cost
- Special equipment
- Potential for injury (unfounded)
What factors influence the treatment of CHD
- Px age
- Degree of discomfort
- Physical & radiographic findings
- Client expectation
- Finances
What percent of young px return to acceptable function w/ medical or conservative management
~ 75%
When is sx treatment done for CHD
- When conservative tx is not effective
- When athletic performance is desired
- Slow progression of DJD & enhance probability of good long term limb fxn
Describe short term medical/conservative management
- Complete rest 10 - 14 days
- Moist heat
- PT
- NSAIDs
- Chondroprotective agents
Describe long term medical/conservative management
- Weight control
- Exercise like walking & swimming
- NSAIDs
- Chondroprotective agents
What NSAIDs are used to treat CHD
- Carprofen
- Derocoxib
- Meloxicam
- Previcox
List chondroprotective agents w/ the potential to treat CHD
- Parental polysulfated glycosaminoglycans (adequan)
- Oral glucosamine & chondroitin sulfate (glycoflex & cosequin)
