Final Exam - Joint Disease of the Hip Flashcards

1
Q

what is the pathogenesis of canine hip dysplasia?

A

laxity develops during skeletal growth because the soft tissues supporting the hip are unable to develop & keep pace with rapid bone growth - laxity results in subluxation of the hip joint during weight bearing with repetitive luxation resulting in lameness

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2
Q

what is the 2nd most common cause of pelvic limb lameness?

A

canine hip dysplasia

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3
Q

why is canine hip dysplasia considered to be developmental & not congenital?

A

hips are normal at birth

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4
Q

T/F: canine hip dysplasia is typically a bilateral disease

A

true

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5
Q

what factors have been directly implicated in canine hip dysplasia?

A

breed - common in large/giant breeds (GSD, st bernards, goldens, labs)

diet - maximizes trait expression in genetically susceptible individuals

body weight - obesity

sterilization - OHE/neuter increases risk

activity level - worsens clinical signs associated with disease

maternal factors - increased relaxin, testosterone, estradiol

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6
Q

what is the one phrase that can be used to describe the underlying pathophysiology of CHD?

A

excessive joint laxity

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7
Q

what is the source of the lameness in early canine hip dysplasia?

A

activation of pain fibers within the ligament of the femoral head, joint capsule, & labrum - not osteoarthritis

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8
Q

what has occurred in a dog with CHD that has the resolution of clinical signs by 12-18 months of age?

A

the body responds to excessive joint laxity & attempts to stabilize the joint through fibrosis of the joint capsule & ligament of the femoral head - the fibrosis can be capable of resolving clinical signs but doesn’t mean the patient is cured

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9
Q

what is the bimodal age distribution for dogs with CHD?

A

young dogs - display clinical signs because of excessive joint laxity, joint subluxation, & soft tissue pain

mature dogs - display clinical signs because of OA that occurs secondary to previous joint laxity

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10
Q

what is the typical history of a young dog with CHD? what about an old dog?

A

young - bunny hop gait, acute signs, can be identical to CCL ruptures, normal sit test

mature - pet is ‘getting older’, difficulty rising, insidious/slowly progressive

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11
Q

what is an ortolani sign?

A

physical exam test used to detect joint laxity - one hand is placed on the dorsal aspect of the pelvis for counter pressure

stifle is flexed 90 degrees & cradled with the other hand, hip is put into a weight bearing position & firm pressure is generated by compression hands together, while maintaining pressure - limb is slowly abducted

during early phases of CHD - a palpable/visible click or pop occurs as the femoral head reduces within the acetabulum

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12
Q

T/F: normal puppies can have a positive ortolani sign until approximately 4-6 months of age

A

true - if present after 6 months of age, suggestive of CHD

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13
Q

why may a mature dog not have a positive ortolani sign?

A

as OA develops within the hip, acetabular infilling with new bone occurs resulting in loss of a normal acetabular depth - result is a loss of a deep structurally normal acetabulum to allow for reduction of the femoral head

as the body responds to excessive laxity, periarticular fibrosis develops & may limit the examiner from subluxating the femoral head

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14
Q

why are sedated radiographs necessary for a dog with CHD?

A

to rule out other causes of lameness, confirm the clinical diagnosis, to provide the owner with recommendations regarding breeding, & to classify or stage the patient’s hips (is the dog in early phases of CHD but no OA? has the dog developed OA? radiographic severity?)

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15
Q

what radiographic techniques are commonly used to evaluate & grade CHD?

A

OFA-style & pennhip

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16
Q

what are the advantages & disadvantages of using OFA-style rads for CHD?

A

advantages - excellent for identifying OA & helpful in determining phase/stage of CHD

disadvantages - can miss early cases, if submitting for OFA, can’t be graded until 2 years of age

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17
Q

how are pennhip rads taken?

A

rads of the hip joints are obtained with the hips in a weight bearing position before & during the simulation of weight bearing - measurements are made creating a distracting index where a DI of 0 indicates zero laxity & a DI of 1 indicates complete luxation

18
Q

if you have a DI <0.3 on pennhip rads, what does that mean? what about a DI of >0.7?

A

<0.3 - no laxity/subluxation, unlikely to have CHD

> 0.7 - excessive joint laxity/subluxation, likely to have CHD

19
Q

what is the use of pennhip rads?

A

used to predict the likelihood of development of future CHD based on an objective measure of laxity - big tool for breeders wanting to make selections before 2 years of age

20
Q

what are the treatment goals for CHD?

A

controlling clinical signs, elimination of excessive laxity, & treatment of existing OA

21
Q

what are the indications for a juvenile pubic symphysiodesis?

A

young dogs ideally 16-20 weeks of age with clinical signs of CHD, positive ortolani, & must be free of OA

22
Q

what is the goal of performing a JPS?

A

correcting excessive joint laxity by improving dorsal acetabular rim coverage of the femoral head during skeletal growth

23
Q

how is a JPS performed?

A

small ventral approach is made to the pubic symphysis where it is cauterized resulting in necrosis/growth arrest of this portion of the pelvis - as the puppy grows, the sacrum widens & the remainder of the pelvis grows resulting in lateral rotation of the dorsal acetabular rim

results in improved coverage of the femoral head, improved hip congruity, resolution of laxity/subluxation, & resolution of clinical signs

24
Q

why must you spay/neuter a dog when a JPS is done?

A

there will be no evidence of the surgery once maturity is reached & the animal could pass certification for breeding if left intact

25
Q

what are the indications for a triple pelvic osteotomy?

A

young dogs, 6 months to 1.5 years, with clinical signs of CHD, positive ortolani, & must be free of OA

26
Q

what is the goal of the TPO/DPO surgery?

A

corrects laxity acutely by rotating the acetabulum laterally to capture the femoral head & eliminating hip subluxation & associated clinical signs

27
Q

what is the procedure of a TPO?

A

osteotomies are performed at the pubis, ischium, & ilium - acetabulum is rotated laterally & held in position with a specialized TPO bone plate that is placed on the ilium

plate maintains the new acetabular orientation until bone healing occurs

28
Q

how is a DPO performed?

A

same as TPO except ischial cut is omitted which results in a more physiologic rotation of the dorsal acetabular rim & clinically more stable hemipelvis which improves patient comfort & accelerates return to function

29
Q

why is it recommended to use specialty locking plates when doing a DPO?

A

the DPO places increased strain on the bone-screw-bone interface

helps maximize success & prevent complications

30
Q

what are the indications for an FHP?

A

young dogs with severe CHD & OA that have failed medical management, hip luxation secondary to CHD, mature dogs with moderate to severe OA that have failed medical management, & dogs that could be candidates for THR but have other constraints

31
Q

what is the goal of an FHO?

A

source of the lameness is typically the OA & associated bone on bone contact of the femoral head with the acetabulum

FHO addresses the lameness through surgical removal of the femoral head, most of the femoral neck, & occasionally some of the lateral acetabulum

surgical removal of the painful joint eliminates bone on bone contact, OA-mediated pain, & allowing for adequate limb function

32
Q

how is an FHO performed?

A

craniolateral approach to the hip followed by the transection of the ligament of the femoral head & isolation of the femoral head & neck

ostectomy is made from the base of the greater trochanter to the base of the lesser trochanter & the head & neck are removed

the joint is not replaced - soft tissues are interposed & sutured between the acetabulum & the femur & a false joint forms over time

33
Q

what is required for a successful outcome of an FHO?

A

meticulous surgical technique & early/regular rehabilitation & rechecks during the post-operative period

34
Q

what are the complications associated with FHOs?

A

dogs that undergo FHOs will have a slightly shortened leg & abnormal gait post op due to the mechanical effects of the procedures

35
Q

what are the indications for a total hip replacement?

A

young dogs with moderate to severe CHD & radiographic OA, owners who expect a high level of function, hip luxations, mature dogs with mild to severe OA, acute femoral head/neck fractures, & malunion acetabular fractures

36
Q

what is the goal of a THR?

A

surgical removal of the femoral head & articular portion of the acetabulum & replacing the diseased joint with an artificial joint

the replaced hip eliminates pain & allows completely normal limb function

37
Q

how is a THR performed?

A

similar to an FHO with less bone removed from the femoral neck - acetabular reamer is used to remove the articular portion of the acetabulum & an acetabular implant, femoral head & neck implant are placed

38
Q

what is the gold standard for treating CHD?

A

THR

39
Q

what are the 4 complications associated with THR?

A
  1. luxation
  2. infection
  3. aseptic loosening
  4. femur fracture
40
Q

what is the suggested approach for speaking with clients about options for CHD?

A

evaluate each patient, determine stage of CHD, & offer all relevant treatments giving detailed pros & cons for each

41
Q

____ & ___ are surgical treatments for young CHD dogs without OA

A

JPS & DPO

42
Q

____ & ___ are surgical treatments for mature CHD dogs with moderate to severe OA

A

THR & FHO