Hip Dysplasia Flashcards
describe the anatomy of the hip joint
- ball and socket join, most freely moving of all synovial joints
- movement is multi-axial: flexion/extension, abduction/adduction, circumduction, rotation
- in general the hip is very forgiving and tolerant of a lot of pathology (can manage pathology medically for longer than you can stifle or other joint pathology
what is hip dysplasia?
- one of the most common ortho conditions of the dogs
- end result is inflammation and osteoarthritis
- causation is still unclear, but general theme is that hip laxity during development leads to hip OA
describe how hip dysplasia is biphasic
1st phase: when animal is young, will see laxity of hip and subluxation (hurt because hips are loose)
2nd phase: patients present due to shallow acetabulum, flattening of the femoral head, and osteoarthritis several years later
describe the history and clinical signs of hip dysplasia in young dogs
-typical time of first presentation is 5-12 months old
-history:
1. sudden or insidious onset of unilateral or bilateral hindlimb lameness
2. bunny-hopping
3. difficulty rising after rest
4. reluctance to walk, run, jump, climb stairs, exercise intolerance
clinical signs: attributed to joint laxity and secondary pain!
-rage from slight discomfort to severe acute or chronic pain
describe history and clinical signs of hip dysplasia in mature dogs
history:
1. bilateral or unilateral pelvic limb lameness
2. stiff pelvic limbs, esp after rest or in a day following heavy activity
3. reluctance to walk, run, jump
clinical signs: mostly attributable to osteoarthritis!
-if unilaterally affected, a lameness is discernible but RARELY SEE NON WEIGHT BEARING LAME WITH HIP DYSPLASIA
-if do see non weight bearing lame, consider CCLR!!
what are other rule outs for pelvic limb pain? how do you do this?
full physical, neuro, and ortho exam!!
young dogs: panosteitis, OCD, HOD
mature dog: CCL disease, LS disease, neoplasia, other neuropathies, other ST injuries
describe the gait changes of young and old dogs with hip dysplasia
young:
1. sudden or insidious onset
2. BUNNY HOPPING
3. unilateral or bilateral hindlimb lameness
4. hip or spinal sway
5. difficulty rising after rest
6. exercise intolerance
mature:
1. history of bilateral or unilateral pelvic limb lameness
2. difficulty rising
3. hip or spinal sway
4. stiff pelvic limbs, esp after rest of heavy activity
5. exercise intolerance
in general!! hip dysplasia dogs are reluctant to do activities that require hip extension!!! don’t like to jump UP, climb UP
may also see straight hocks: to keep hips flexed
describe palpation of hip dysplasia for young and mature dogs
young:
1. pain on hip extension!!
2. palpable signs of laxity (ortolani test)
mature:
1. pain on hip extension!!
2. reduced range of motion
3. muscle atrophy
4. diminishing evidence of ortolani as OA remodeling takes over
describe the ortolani test
2 parts: trying to subluxate hip and then reduce it; if can subluxate, then the hip has some laxity to it! only do when sedated
- the barlow test: limb is in an adducted position and force is directed proximally to create subluxation of the lax hip joint
- the ortolani test: the limb is abducted, maintaining the proximally directed force along the axis of the femur, and a click or a clunk can be heard and/or palpated as abrupt reduction of the femoral head occurs; the clunk is the positive ortolani sign and suggest laxity of the hip joint
describe diagnostic radiographic methods -orthopedic foundation for animals (4)
- evaluates hips on extended hip radiograph, one view
- advantages: easy to perform, anyone can do it, no special equipment needed
- disadvantages: performed at 2 years of age (can’t prevent anything), joint capsule wind up tightens hip (not normal position, as you twist the hip it looks less lax), subjective scoring system, most dogs graded as acceptable for breeding are not acceptable by other subjective measures
- scored by consensus of three radiologists on a 1-7 scale with 1-3 being normal, 4 being borderline, and 5-7 being dysplastic
describe diagnostic radiographic methods for hip dysplasia- PennHIP
PennHIP: evaluates in a neutral hip position; with a distracted view! perform at 16 weeks old, is a predictive
- 3 views!
-hip extended dorsal view: assess for osteoarthritic
-hip neutral-compression view: assess for congruency of femoral head within acetabulum
-hip neutral-distracted view: allows calculation of distraction index- QUANTIFIES LAXITY - distraction index (DI) = d/r
-d = distance between geometric center of the femoral head and the geometric center of the acetabulum
-r = radius of the femoral head
-0 = no laxity
-1 = 100% laxity
-clinical relevance: <0.3 is no risk for OA, >0.3 is at risk for OA and >0.7 is extreme laxity and preventative measures may not be effective! - advantages:
-can be done at 16 weeks of age; is predictive! can help predict the likelihood of developing DJD (OA) as dog ages
-most evidence-based method
-has predictive value (dogs compared to others within breed
-all films entered into database (no selection bias) - disadvantages:
-requires special training to become PennHIP certified
-requires special equipment (distractor)
describe other radiographic signs of hip dysplasia
- Puppy line: indistinct linear sclerosis on femoral neck
-seen in dogs 18 months or younger
-nonpathologic
-not related to later OA or CCO - Morgan’s line: caudolateral curvilinear osteophyte
-early osteophytic sign that is an important indicator of disease presence and progression later in life
-often the FIRST radiographic sign of OA!!!
-if present, 3.7x more likely to develop OA - circumferential femoral head osteophyte
-early osteophytic sign that is an IMPORTANT predictor of disease presence and progression later in life
->80% of dogs with CFHO developed radiographic evidence of OA
describe treatment options for hip dysplasia in young dogs (3)
- medical/conservative therapy: slow progression and manage secondary OA
- JPS: juvenile pubic symphysiodesis
-age for treatment: 12-20 weeks old, best is 12-16 weeks old (correlate with PennHIP!)
-how it works: fuses pubic symphysis using electrosurgery, utilizes remaining growth potential of pelvis to rotate and reorient the acetabula over the heads of the femurs!
-very successful with dogs with mild to moderate laxity (DI) - pelvic osteotomy:
-procedures: - double pelvic osteotomy (DPO): ilium and pubis
- triple pelvic osteotomy (TPO): ilium, pubis, ischium
-how it works: reorientation and rotation of the acetabulum to increase dorsal coverage of the femoral head; improves joint stability and congruence
-works just like a JPS but requires osteotomies!
-candidates: no OA!!, positive ortolani sign, no severe laxity
-risks: implant failure, sciatic nerve injury
describe treatment options for mature dogs with OA present for hip dysplasia (3)
- medical/conservative therapy: slow progression and manage secondary OA
- FHNE or FHO
-age for treatment: 12 months and older (mostly)
-how it works: excision of femoral head and neck makes animal form a pseudoarthrosis/false joint
-post-op care: rest for two weeks while soft tissues heal, then activity is encouraged to promote false joint formation
-prognosis: most do really well; negative prognostic indicator is muscle atrophy, the worse the atrophy the harder the recovery
- total hip replacement:
-age for treatment: 12 months or older (mostly)
-how it works: replacement of femoral head/neck and acetabulum with an artificial hip replacement system
-potential serious complications: 18%
–hip luxation, sciatic neuroplasia, implant loosening, infection, femur fracture
-post op care: exercise restriction for 8 weeks, recheck rads in 8 weeks and if good, rest for 6-8 more weeks before gradual return to normal activity
-prognosis: 90% owner satisfaction
-2 types:
–cemented THR: use of bone cement to secure implants, immediate stability as cement hardens but wears out after 11 years
–non-cemented THR: use of body/bone growth to secure implants; areas on implants are porous to allow bone to grow into them and final stability occurs as bone grows into the implants
