Hip dysplasia Flashcards
Why aren’t X-rays always significant in hip dyplasia?
There is a poor correlation between the radiographic and clinical signs therefore assessment of the significance of X-ray changes is always made in the light of clinical signs
What is the aetiology of hip dysplasia?
Genetic predisposition resulting from breeding for “desirable” breed characteristics
* Associated with rapid growth
* Over supplementation of calcium has also been implicated as a cause
What changes in the hip joint occur in hip dysplasia?
- Poor joint conformation results in increased laxity, synovitis and increased synovial fluid
- This in turn results in greater subluxation of the hip and a vicious cycle of pathological changes
- Degenerative changes occur within the joint which become more apparent with age
- These changes include radiographic evidence of osteoarthritis and clinical signs of joint disease
- The latter include stiffness on rising, pain, poor muscle development and lameness
What signalment is common with hip dysplasia?
- Common breeds: Labrador, Golden retriever, Newfoundland ,German shepherd, Cavalier King Charles spaniel
- Age at onset:- 6-12 months
What clinical history is associated with hip dysplasia?
- Pain on rising
- Swaggering/swaying gait
- Bunny hopping
- Occasionally squeal out, particularly on rising
- Acute presentations can occasionally occur with micro-fractures of the acetabular rim
- Poorly muscled (gluteals)
- Pain on manipulation of the hips particularly on extension
- Subluxation maybe detected (the Ortolani sign)
- A clunk as the hip reduces after being subluxated
- As the condition is usually bilateral an obvious lameness may not be present
How would you diagnose hip dysplasia?
- Clinical signs and signalment- these can give a high degree of suspicion and are important when assessing the radiographic signs
- Clinical examination
- Radiography- interpreted in the light of the clinical signs and examination
What would you include in your clinical exam investigating hip dysplasia?
- Joint laxity is dependent upon joint capsule thickness, integrity of ligament of femoral head, integrity of dorsal acetabular rim and muscle tension
- Barden’s palpation (hip lift) –the hip is lifted from the acetabular by grabbing the diaphysis of the femur
- Barlow’s sign (this is the first part of the Ortolani manoeuvre when the hip dorsally subluxates
- Ortolani test (sedation / GA required)
The Barden hip lift test - a positive result is when the hip is lifted greater than 0.5 cm from the acetabulum
Ortolani test
* Performed under GA or heavy sedation
* Dog in dorsal recumbency
* Pressure applied towards the table to subluxate the hip
* Abduct the hip till it clunks into the acetabulum (the angle of reduction)
* Adduct the hip till it re-luxates (the angle of subluxation)
What x-ray view do you want to diagnose hip dysplasia?
Standard extended ventro-dorsal view of the hips
* This is the view for the BVA/KC scheme
* Hips are inwardly rotated so that the patellas overlie the trochlea groove of the femurs and the hind limbs are extended
* This can result in a reduced degree of subluxation driving the femoral heads into the actetabulae
What are early and late radiographic signs of hip dysplasia?
Early signs of hip dysplasia
* Subluxation of the joint with poor coverage of the femoral head by the acetabulum
* Sclerosis of the cranial acetabular edge
50% if the femoral head should be within the acetabelum - there the left hip is not 50% within - subluxation
Late signs of hip dysplasia –>
* The hips remain subluxated
* Marked remodelling of the femoral heads
* Remodelling of the acetabulums with marked sclerosis and new bone on the caudal and cranial edges
* Extensive new bone on the femoral neck at the joint capsule attachments
What does the PennHIP test measure? What findings are normal? Why is it not done in the UK?
The PennHIP test measures the degree of subluxation
* The distraction index is the (DI)
◦ DI = distraction distance (d) /radius of femoral head (r) i.e.(d/r)
◦ 0 = perfect congruity
◦ 0.3 - 0.7 = abnormal
◦ 1 = complete luxation
* This test in more useful in the younger animal when joint instability is at its greatest and gives a good indication of the degree of hip dysplasia
* The test is not appropriate in the UK due to the requirement to hand hold unless using a mechanical distraction device is used
What would you recomment for the conservative management of hip dysplasia?
- NSAIDs
- Physiotherapy to increase gluteal mass resulting in greater joint stability
- Nutraceuticals
- Cartrophen
(See management of osteoarthritis) - weight management
- exercise regime - consistent exercise
The majority of dogs presenting in the first year of life can be managed conservatively but if this fails there are several surgical options available
When the hip becomes stable, which it does as a result of increased muscle mass, periarticular fibrosis and new bone formation within the joint, the clinical signs will disappear for several years
What surgical management is available for dogs 16 weeks old or less?
pubic symphysiodesis
* This is fusion of the pubic symphysis with a diathermy probe to cause premature closure of this growth plate
* This results in the pelvis rotating and capture of the femoral heads
* no control of how the rest of the pelvis grows - can end up with a narrow pelvic canal also risk of thermal injure to the surrounding tissues
What surgical management of hip dysplasia is aviailable until a dog is 12 months old?
triple (TPO) or double pelvic osteotomy (DPO
- In the latter only the ilial shaft and pubis are cut in the former the ischium is cut also
- These techniques isolate the acetabular segment of the pelvis
- It is then rotated to increase the dorsal covering of the femoral head by the acetabulum
- The segment is fixed with a special plate which has set degrees of rotation (20 30 and 40 degrees)
young dog that are already showing signs of hip luxation, document signs of hips luxation but not showing signs of secondary bone changes
What palliative treatment is available for hip dysplasia?
Pectineal myotomy
* This technique is straight forward and consists of sectioning the pectineal muscle
* It is suggested that this allows the femur to abduct slightly and increase weight bearing on the acetabular surface and reduces tension on the joint capsule both of which reduce pain
* The effects are generally temporary
* It can be employed in both the young and older animal
What surgical treatment is available for hip dysplasia in the mature dog?
- Femoral head and neck excision/ostectomy. Large dogs do less well with this technique
◦ cut above lesser trochanter across to the greater trochanter
◦ need fibrosis to occur to secure the femur, need to ensure the joint is moving 3-5 days post-op - lead walks to build this up correctly
◦ limb function will never be as good
◦ limb will be shorter - Total hip replacement for the mature dog
What control scheme is available for hip dysplasia? How is it undertaken?
The BVA/KC HD scheme
- Subject must be greater than 1 year old but does not need to be Kennel Club registered
- Examination requires GA or heavy sedation
- Date, KC registration number, identichip or tattoo number and L/R marker must be present on the radiograph
- 9 parameters are assessed each with a value of 6 except the caudal acetabular edge with a value of 5
- Total score 106 (53 for each hip)
- The lower the score the better the hips
- The score needs to be compared with the breed median
- Both hips need to be below the breed median to make the dog a suitable breeding candidate
What are the limitations of the BVA/KC control scheme?
- An assessment is being made of the genotype from a phenotypic measurement
- No allowance is made for the age of the dog (older dogs presented to the scheme inevitably have more secondary changes)
- There is no compulsion to have dogs with poor hips scored cf. Scandinavian countries
- The breed mean/median is a historical value although now averaged over five years
- The breed median rather than the mean is used to reduce the effects of outliers
- One should only breed from dogs whose worse hip is less than the breed median
- The age of the dog should be taken into consideration when assessing suitability to breed
- There is no compulsion overall to take part in the scheme when breeding dogs
Are cats affected by hip dyplasia? How does it present? How can it be treated?
- Larger breeds affected particularly the Main Coon, Persian and Himalayan
- Osteoarthritis develops later than in dogs
- Clinical signs are difficult to identify in the cat but may include a reluctance to exercise or jump onto work surfaces, reduced grooming
- Most cats can be managed with conservative treatment
- Femoral head and neck ostectomy or total hip replacement can be employed to manage this condition surgically
- Total hip replacement is prone to complications but has a more consistent outcome than femoral head and neck ostectomy
