Hip dysplasia

Question 1

Define Developmental dysplasia of the hip

Answer 1

Encompasses a spectrum of disorders describing abnormal development of the femoroacetabular joint in children and babies. Can be idiopathic or teretologic.

• Abnormality: size, shape, organization
• Involved anatomy: femoral head, acetabulum, or both
• Result: femoral head subluxation, instability or dislocation

Question 2

What the difference between idiopathic and teratologic DDH?

Answer 2

Idiopathic : Dysplasia, subluxation, dislocation of the hip that happens without known cause.

Teratologic : A syndromic cause, usually genetic or neuromuscular disorders. More severe fixed dislocation prenatally and often surgery is needed.

Question 3

Epidemiology and etiology of DDH

Answer 3

1 in 100 live births screened clinically
8 in 100 infants screened with DUS

Question 4

Explain why regular radiographic examination of the hip with new borns has limited value? What is the best choice for evaluating DDH and why?

Answer 4

Their femoral heads do not ossify until four to six months.
Ultrasonography is the choice in infants younger than 6 months (capable of visualing the cartilaginous anatomy of the femoral head and acetabulum).
Too sesensitve prior to 6 weeks, in general should not be ordered until after

Question 5

Ortolani test:

Answer 5

• Sign of relocation of dislocated hip
• Hip flexed to 90, gently abducted, and the greater trochanter is lifted anteriorly.
• Palpable clunk sensation is a positive.

Question 6

Barlow Test:

Answer 6

Gentle downward force applied to adducted hip.
- Reveals hip instability (reverse of ortolani)
- Hip flexed to 90, posterior force, adducted 10-20
- Palpable dislocation = positive

Question 7

Galeazzi Sign:

Answer 7

Elicited by placing the child supine, with both hips flexed at 90 degrees, and knees flexed.

• affected hip will appear to be shorter, usually from
  hip dislocation or congential femoral shortening.

Question 8

Reference lines for evaluation of AP view of infants pelvis

Answer 8

Hilgereiner’s line- Horizontal through triradiate cartilages of the pelvis.

Perkin’s line- perpendicular to hilgereiners at the lateral edge of each acetabulum.

Shenton’s line- curvilinear, defined by the medial border of the femoral neck and superior border of the obturator foramen.

Question 9

Explain the management strategies used in DHD

Answer 9

• Early treatment = greater success and lower incidence of residual dysplasia and long term complications
• Subluxation often corrects spontaneously, may be observed for 2 weeks without treatment
• Double or triple diaper technique (theoretically corrects adduction)
• When subluxation persists beyond 2 weeks, refer for management

Education: Importance of positions of swaddling legs in extended and adducted posture. Instead allow free movement of legs

Question 10

What is the Pavlik Harness:

Answer 10

Primary method for treating DDH during infancy
Restricts extension and ADDuction, allows the hips to maintain flexion and abduction (protective postion)

Question 11

Screening aim for DDH

Answer 11

• Early detection
• Treatment with abduction split within 1st 6-8 weeks after birth
• Avoid surgery with long term morbidity (OA)

Question 12

What is a common finding with unilateral hip dislocation; not specific to the condition

Answer 12

Asymmetric skinfolds or leg length inequality

Question 13

An infant with hip dislocation will develop what limitation?

Answer 13

hip abduction by 3 months of age. The first sign on the affected side may be trendelenburg gait.

Question 14

What is often the first sign of hip dislocation?

Answer 14

Trendelenburg on the affected side when walking

Question 15

When taking your reference lines, where should the femoral head lie? Include the lines are used.

Answer 15

Femoral head should lie within the inferomedial quadrant formed by the hilgenereiners and perkins line.

Question 16

A break in the Shentons reference lines suggest

Answer 16

Displacement of the femoral head from the bony acetabulum.

Question 17

6m old infant with acetabular dysplasia of the right hip is diagnosed by radiograph, with a hx of dislocatable hip at birth, would usually be treated with
a. Open reduction
b. Spica cast
c. Arthrogram and closed reduction
d. Pavlik harness

Answer 17

d. Pavlik harness

Question 18

Factors contributing to DDH include: (4 marks)

Answer 18

• Breech presentation
• Female sex
• (+) family Hx
• First born status

Question 19

Screening for DDH occurs at birth with all babies. What is the aim of the screen? (3 marks)

Answer 19

• Early detection
• Treatment with abduction split within first 6-8 weeks after birth
• Avoid surgery and long term morbidity (hip OA)

Question 20

What are 4 signs during a physical examination that indicate DHD

Answer 20

• Hip abduction
• Leg length discrepancy
• Asymmetry of buttock
• Leg creases

Question 21

What provocative dynamic tests should be performed to assess an infants hip stability? When are they no longer reliable and why?

Answer 21

• Ortolani and Barlow maneuvers
• After 3 months the tests aren’t reliable because of soft tissue contractures limiting the motion of the hip, even when dislocated.

Question 22

What is the importance of the protective position when using a pavlik harness?

Answer 22

The position of flexion and ABDuction enhances normal acetabular development and the kicking motion in the position stretches the contracted hip adductors, while promoting spontaneous reduction of the dislocated hip.

Question 23

What is an alternative to a pavlik harness for treatment of acetabular dysplasia with or without subluxation? When would this alternative be recommened?

Answer 23

Abduction orthosis. For 9 months or older, and who are beginning to walking independently. The alternative is designed so the child can walk while in the orthosis.