Total hip replacement

Question 1

What is hip dysplasia characterised by?

Answer 1

Hip laxity and or instability

developmental disease of the hip

Question 2

At what age does hip laxity develop?

Answer 2

4-5months

Question 3

What environmental factors influence hip laxity?

Answer 3

size of dog, rate of growth, diet and exercise

Question 4

What clinical conditions can arise due to hip laxity?

Answer 4

inflammation
microfractures (acetubular rim)
Pain
Thickening of the joint capsule
Remodelling via erosion of the cranial and caudal borders acetabulum
Round teres ligament stretched or ruptured
femoral head flattened

Question 5

When do skeletal changes occur in the dog with hip laxity?

Answer 5

During growth in the first year of life

Question 6

What does hip laxity present with?

Answer 6

Bunny hopping 
frequent sitting
Lateral sway of the spine 
exercise intolerance 
clicking of the hips 
difficulty rising 
pelvic limb lameness/stiffness

Question 7

What will a dog with hip laxity experience during an orthopaedic examination?

Answer 7

Pain on abduction and hip extension
Audible click
instability
Muscle atrophy (biceps femoris and gluteals

Question 8

What investigations are carried out when assessing hip laxity?

Answer 8

radiography (orthogonal views, ventraldorsal extended and lateral)
Quantify the degree of laxity via radiography
Ortoloni test (not useful in dogs that are older)
Identification secondary arthritis
Ultrasound

Question 9

What may conservative management include for the hip dysplasia dog?

Answer 9

Restricted diet
short lead walks
NSAIDS
introduce hydrotherapy

Question 10

Why is it important to try conservative treatment first in the young dog with hip dysplasia?

Answer 10

Joint may stabilise with time by fibrosis and bone remodelling

Question 11

What are the aims of treatment in hip dysplasia?

Answer 11

Minimise pain and swelling
improve limb function
reduce the progression of osteoarthritis

Question 12

How is a decision made as to whether surgical or medical management should be tried in hip dysplasia?

Answer 12

Dogs age 
presence of arthritis 
dogs behaviour 
potential use
severity of clinical signs

Question 13

What two types of surgical treatment can a hip dysplasia dog undergo?

Answer 13

Prophylactic procedures

Salvage procedures

Question 14

What prophylactic procedures can a dog undergo for hip dysplasia?

Answer 14

Triple pelvic osteotomy

Juvenile pubic symphysiodesis

Question 15

What is involved in a juvenile pubic symphysiodesis?

Answer 15

Fusion of the pubis symphysis growth plate
improves hip congruence
only suitable young dogs no signs of secondary arthritis
increased femoral head coverage

Question 16

What is involved in a triple pelvis osteotomy?

Answer 16

Increase the dorsal coverage of the femoral head
Moderate hip laxity angle of reduction less than 35 degrees
no OA between 4 and 8 months of age
Pelvis is cut in two or three places and the acetabulum is freed

Question 17

What are the salvage procedures that can be preformed in the hip dysplasia dog?

Answer 17

femoral head and neck excision

Total hip replacement

Question 18

What is involved in a femoral head and neck excision?

Answer 18

Femoral head and neck are removed allowing for psuedoathrosis to form
(smaller dogs do better)
Younger dogs with severe laxity or older dogs
Preserve soft tissue leaving articular bone surface

Question 19

What is the postoperative management of Femoral head and neck excision?

Answer 19

Encourage exercise as soon as sutures are removed to achieve mobile pseudoarthrosis
initiate physiotherapy 2-3days after surgery

Question 20

What are the two methods of completing a total hip replacement?

Answer 20

Bone cement implant

Non-cemented systems (new)

Question 21

who are the ideal candidates for THR?

Answer 21

chronically painful arthritic hips
no concurrent ortho or neuro issue
Conservative management tried and failed 
not overweight 
no other concurrent problems

Question 22

When should a THR be preformed in young dogs with severe hip laxity?

Answer 22

9 months of age once their growth plates have fused.

Question 23

How long should be left between bilateral hip surgeries?

Answer 23

6-8weeks

Question 24

what are the indications for THR?

Answer 24

advanced coxofemoral osteoarthritis

Question 25

What are the advantages and disadvantages of a cemented THR?

Answer 25

90-95% success rate
Once in place difficult to remove
Bone must be prepared, pulsatile lavage (remove cancellous bone), plug to pressurise cement, cement gun centralizers

Question 26

What are the advantages and disadvantages of non cemented THR?

Answer 26

Recent development 
size of implant must be correct, dependant on a tight fit
Quicker procedure 
revision surgery easier 
ingrowth of bone can occur

Question 27

What are the complications of THR?

Answer 27

infection 
implant failure 
luxation 
osteomyelitis 
aseptic loosening 
femoral fractures 
subsidence 
sciatic neuropraxia 
cement granuloma

Question 28

What discharge instructions would you write for a THR?

Answer 28

Exercise severly restricted
minimal lead walks 6 weeks 
Avoid play and slippery floors 
Re-examined at the end of 6 weeks
Gradual return to exercies