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Small Animal Surgery > Canine Hip Dysplasia > Flashcards

Canine Hip Dysplasia Flashcards

1
Q

What signalment is associated with hip dysplasia? What are the most common signs?

A

large and giant breeds, presenting as early as 5-12 months

  • lameness —> painful to advance limbs
  • gait changes —> bunny hopping, wiggling hips
  • chronic form is less dramatic
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2
Q

How is the joint manipulated to diagnose hip dysplasia?

A

Ortolani - place a hand on the spine and drive the stifle up, then abduct —> positive sign is a “clunk feeling when the femoral head slips down into the acetabulum

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3
Q

How are OFA radiographs performed for diagnosing hip dysplasia?

A

straight VD pelvis with femurs parallel

  • triangular femoral head
  • decreased coverage of acetabulum
  • dorsolateral luxation
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4
Q

What are the 4 most common radiographic signs of hip dysplasia?

A
  1. femoral periarticular osteophytosis
  2. subchondral sclerosis of the craniodorsal acetabulum
  3. osteophyte formation on the cranial or caudal acetabular margin
  4. joint remodeling from chronic wear
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5
Q

Hip dysplasia:

A
  • osteophytosis
  • absence of acetabulum
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6
Q

Hip dysplasia:

A
  • osteophytosis
  • remodeled femoral head
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7
Q

How is femoral head coverage affected by hip dysplasia?

A

measurement of femoral head displacement from acetabulum, with normal being >50%

decreased coverage with hip dysplasia

  • remember, radiographs are static and hip dysplasia is dynamic!
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8
Q

What is the Norberg Angle? How is it affected by hips dysplasia?

A

line connecting center of femoral heads and to each craniolateral acetabular rim, making an angle normally > 105 degrees, a tight hip

angle on inclination decreases with luxation = laxity!

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9
Q

What 3 views are required for PennHIP’s hip dysplasia diagnosis? What does it require?

A
  1. ventrodorsal hip extended - DJD, DI
  2. compression - congruency of femoral head and acetabulum, acetabular depth, and cartilage thickness
  3. distraction - passive laxity

general anesthesia, distractor

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10
Q

What information does PennHIP radiographs give?

A

quantification of femoral head displacement —> greater distraction index (DI) = increased laxity

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11
Q

When can PennHIP be used for hip dysplasia diagnosis? What else can it be used to assess the risk of?

A

as early as 16 weeks —> dogs with increased DI (looser hips) will develop radiographic and clinical signs sooner than those with lower DI

developing OA later in life

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12
Q

How does distraction index from PennHIP affect likely outcomes and treatment options for patients?

A

DI < 0.3 = tight hips with low likely hood of OA of CH

DI 0.3-0.7 = mild to moderate laxity at risk for developing OA, should considered pre-emptive surgery or medical plans, not all of these patients will develop DJD

DI > 0.7 = severe laxity where preventative measures are ineffective, OA is expected, recommend THR/FHO

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13
Q

How does PennHIP alter their algorithm based on breeds?

A

has breed-specific counts, DI, minimums, maximums, and means, where breeds commonly affected by CHD have higher mean DI

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14
Q

What is cavitation seen on PennHIP radiographs? How does it appear?

A

distraction lowers the intracapsular pressure of the coxofemoral joint, which can cause a void in the formation of synovial fluid due to pressure differential

lucent nitrogen bubbles in the joint space —> no adverse effects to joints, if bilateral repeat in 24 hr

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15
Q

What 2 major surgical procedures are used to save the natural joint when correcting hip dysplasia?

A
  1. juvenile pubic symphsiodesis - 12-20 weeks
  2. triple pelvic osteotomy - 6-12 months
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16
Q

What are the 5 goals to juvenile pubic symphysiodesis?

A
  1. cover femoral head with acetabular hyaline cartilage
  2. achieve and enlarge horizontal weight bearing surface
  3. greater load distribution
  4. decreased resultant joint reaction force
  5. improve joint congruity
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17
Q

When is juvenile pubic symphsiodesis performed? How does it work?

A

12-20 weeks old

monopolar electrocautery is applied to the symphyseal growth plate, causing thermal destruction of germinal chondrocytes and premature bony fusion (closes symphysis, other plates keep growing) = increased ventroversion of the acetabulum and femoral head coverage

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18
Q

What approach is used for juvenile pubic symphysiodesis? What 3 muscles need to be elevated?

A

midline over the cranial half of the pelvic symphysis

  1. gracilis
  2. adductor
  3. external obturator
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19
Q

Juvenile pubic symphysiodesis:

A
  • younger doga 12-20 weeks
  • closes symphysis to ennhance acetabular coverage ot femoral head
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20
Q

What affects tissue necrosis during electrocautery in juvenile pubic symphysiodesis?

A

time —> larger dogs need more time

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21
Q

What structures need to be carefully avoided when performing juvenile pubic symphysiodesis?

A
  • urethra
  • rectum
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22
Q

What 4 changes are expected with juvenile pubic symphysiodesis?

A
  1. shorter, wider pubic rami
  2. rounder, wider obturator foramen
  3. more prominent acetabular fossa
  4. irregular margin of cranial pubis
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23
Q

What objective criteria are used to monitor CT changes following JPS?

A
  • dorsal acetabular rim angle
  • acetabular angle
  • PennHIP distraction index
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24
Q

What are the major pros for performing JPS to treat hip dysplasia?

A
  • treats both hips
  • not technically demanding
  • no implants needed
  • short recovery and surgery time
  • inexpensive
  • few complications
  • can perform a revision later
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25
Q

What are the 3 major cons to performing JPS to treat hip dysplasia?

A
  1. loose or mucoid stool common for 1-3 days
  2. electrocautery burns
  3. asymmetrical fusion
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26
Q

What are the 2 requirements for performing a triple pelvic osteotomy to treat hip dysplasia?

A
  1. laxity WITHOUT degenerative change (hip is worth saving!)
  2. 6-12 months old
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27
Q

What 3 cuts are performed during a TPO? What other equipment is used?

A
  1. pubic
  2. ischial
  3. ilial

pelvic osteotomy plate - 20, 30, 40 degrees available

(pet must be over 30 lbs!)

28
Q

What is the point of performing a TPO for hip dysplasia?

A

tilt hip to drive the femur into the acetabulum when load bearing

29
Q

TPO:

A
30
Q

What is important to note about radiographs following a TPO?

A

the femur will likely still look luxated —> the procedure fixes the luxation upon load bearing (it’s dynamic!)

  • post-op laxity on rads normal!
  • ensure rads are new
31
Q

What are the 5 most common complications associated with TPOs?

A
  1. femoral neck impingement in abduction due to over-rotation (larger plate than needed)
  2. sciatic or obturator neuropaxia
  3. dysuria due to a bilateral procedure
  4. screw loosening - ensure they engage sacrum and use locking screws
  5. infection
32
Q

What do TPOs not treat?

A
  • subclinical osteoarthritis can still occur
  • DJD

TPO > JPS for altering acetabular coverage

33
Q

What are the 2 options for replacing the natural joint when treating hip dysplasia?

A
  1. femoral head and neck ostectomy
  2. total hip replacement
34
Q

What kind of procedure is a FHO? What 4 changes result?

A

salvage, irreversible

  1. shortened limb
  2. significant change in limb biomechanics
  3. decreased ROM
  4. muscle atrophy
    - pot-op rehab and PT important!
35
Q

In what patients is an FHO performed?

A

< 20 kg

immediate and loner post-op rehab needed!

36
Q

What are the 2 major candidates for FHO?

A
  1. clinical signs of lameness and pain not effectively treated with medical management
  2. TPO or THR surgery not an option due to age, size, or economics
37
Q

FHO:

A
38
Q

FHO:

A

too much neck left

39
Q

How is an FHO performed? What post-op management is especially important?

A

complete incision of the femoral head and neck

  • NSAIDs and pain control
  • early weight bearing - ilium and femur can fuse
  • rehabilitation
40
Q

Why would a FHO be recommended?

A
  • cheaper
  • easier
  • faster
  • better than nothing

not the best we have to offer!

41
Q

What are 4 differences between a total hip replacement and other treatments of hip dysplasia?

A
  1. quicker recovery
  2. pain-free
  3. best function after surgery
  4. lasts the life time of the patient
42
Q

What is the goal of total hip replacements? What patients are able to get these?

A

salvage procedure to replace diseased femoral head and acetabulum —> return to normal function in sporting and working dogs

all sizes (up to 125 kg!), over 6 m/o

43
Q

What 5 problems are total hip replacements able to solve?

A
  1. osteoarthritis - primary, hip dysplasia
  2. chronic luxation at CFJ - trauma, CFJ dysplasia
  3. fracture of the femoral head/neck - comminuted, malunion
  4. avascular necrosis
  5. revision of failed procedures - FHP, TPO
44
Q

What patient history and ages are able to receive a total hip replacement?

A

HX - waxing/waning hindlimb lameness, bunny hopping, weight-bearing lameness

AGE - >6 mo, greater trochanter growth plate closure

45
Q

What are the 2 major contraindications for total hip replacements? What are some others?

A
  1. non-clinical patient
  2. geriatric patients responsive to medical management - diet, exercise restriction, NSAIDs, intramuscular PSAGAG, glucosamine
  • other orthopedic disease, septic arthritis
  • dermatitis (pyoderma)
  • neurologic disease (IVDD, LS disease)
  • myopathy
  • neoplasia - histiocytic sarcoma, synovial cell sarcoma
  • immune-mediated disease - hyperadrenocorticism causes delaying healing
46
Q

What are the 3 major systems for total hip replacements?

A
  1. cemented - Biomedtrix CFX
  2. cementless - Biomedtrix BFX, Kyon (Zurich), Helica
  3. Hybrid - CFX-BFX
47
Q

Total hip replacement:

A
48
Q

What are the 2 components of cemented (CFX) hip replacements?

A
  1. FEMORAL - stem, neck, head
  2. ACETABULAR - cup, polyethylene liner
49
Q

How are cement implant sizes determined? What do under-sizing and over-preparation lead to?

A

make a template based off of radiographs

  • UNDER-SIZING = decreased iatrogenic fixation
  • OVER-PREPARATION = limited to cancellous bone
50
Q

What is centralization of cemented hip replacements like?

A

device avoids endosteal contact to avoid femoral fractures

51
Q

How is the femoral component of a cemented hip replacement aligned?

A

centrally along the long axis of the femur

  • mantel 2mm proximally, 20mm distally
52
Q

What 2 femoral component initial stabilization interfaces are available for cemented hip replacements?

A
  1. bone-cement
  2. cement-implant
53
Q

What are the 2 components of cementless hip replacements?

A
  1. FEMORAL - stem with collar or porous coating, neck, head
  2. ACETABULAR - cup of porous coating, polyethylene liner
54
Q

What kind of fit does cementless hip replacements have?

A

press fit with the implant in contact with the cortical bone —> stove pipe femur, no isthmus

55
Q

How are cemented hip replacements placed? What 2 complications are associated?

A

initial stabilization applies friction

  • stress applied at interface (implant-cortical bone) - increases risk of loosening
  • stress applied to bone away from implant increases risk of fracture
56
Q

How are hybrid hip replacements placed?

A
  • CFX (cement) = femoral
  • BFX (cementless) = acetabular
57
Q

What are cemented hip replacements commonly used to correct?

A
  • FHO - low ostectomy at lower trochanter
  • THR - isthmus of the femoral neck
58
Q

What femoral preparation is used for cemented hip replacements?

A
  • drill
  • ream
  • broach
59
Q

What are 3 ways of cement preparation and injection? What is commonly added?

A
  1. slow vacuum mixing. -decreases porosity, increases fatigue strength
  2. pressurization - forces cement into irregularities
  3. retrograde filling - decreases air pockets

antibiotics —> Cefazolin (does not decrease strength)

60
Q

What is the purpose of reaming the acetabulum?

A

removal of cartilage for the insertion of an oversized acetabular implant enabling press fit

61
Q

What are 2 important angles used for proper positioning of cemented hip replacements?

A
  1. lateral opening - >60% dorsal covering = more likely to luxate
  2. version - want a 15-25 degree retroversion to match femoral normoversion-anteversion
62
Q

How do the sizes of femoral head replacements affect their use? How is external rotation of limbs maintained?

A

affect neck length

partial tenotomy of the external rotator muscles

63
Q

Total hip replacement, implant position:

A
64
Q

What are 3 important components of post-operative care following a total hip replacement?

A
  1. analgesics - NSAIDs for 1-3 weeks due to concurrent DJD exacerbation
  2. antibiotics - if culture positive, continue for 1-2 months and monitor for radiographic loosening
  3. exercise restriction - gradual return to activity over 3 months with follow-up radiographs
65
Q

What should the first 3 months following a total hip replacement look like?

A

MONTH 1 - “house arrest,” good traction floors, no stairs, running, jumping, or rough play

MONTH 2 - short leash walks several times a day

MONTH 3 - longer leash walks, no running, jumping, or rough play, gradual return to normal

Small Animal Surgery (34 decks)

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