Hip dysplasia Flashcards
Define Developmental dysplasia of the hip
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
What the difference between idiopathic and teratologic DDH?
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.
Epidemiology and etiology of DDH
1 in 100 live births screened clinically
8 in 100 infants screened with DUS
Explain why regular radiographic examination of the hip with new borns has limited value? What is the best choice for evaluating DDH and why?
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
Ortolani test:
- 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.
Barlow Test:
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
Galeazzi Sign:
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.
Reference lines for evaluation of AP view of infants pelvis
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.
Explain the management strategies used in DHD
- 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
What is the Pavlik Harness:
Primary method for treating DDH during infancy
Restricts extension and ADDuction, allows the hips to maintain flexion and abduction (protective postion)
Screening aim for DDH
- Early detection
- Treatment with abduction split within 1st 6-8 weeks after birth
- Avoid surgery with long term morbidity (OA)
What is a common finding with unilateral hip dislocation; not specific to the condition
Asymmetric skinfolds or leg length inequality
An infant with hip dislocation will develop what limitation?
hip abduction by 3 months of age. The first sign on the affected side may be trendelenburg gait.
What is often the first sign of hip dislocation?
Trendelenburg on the affected side when walking
When taking your reference lines, where should the femoral head lie? Include the lines are used.
Femoral head should lie within the inferomedial quadrant formed by the hilgenereiners and perkins line.
A break in the Shentons reference lines suggest
Displacement of the femoral head from the bony acetabulum.
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
d. Pavlik harness
Factors contributing to DDH include: (4 marks)
- Breech presentation
- Female sex
- (+) family Hx
- First born status
Screening for DDH occurs at birth with all babies. What is the aim of the screen? (3 marks)
- Early detection
- Treatment with abduction split within first 6-8 weeks after birth
- Avoid surgery and long term morbidity (hip OA)
What are 4 signs during a physical examination that indicate DHD
- Hip abduction
- Leg length discrepancy
- Asymmetry of buttock
- Leg creases
What provocative dynamic tests should be performed to assess an infants hip stability? When are they no longer reliable and why?
- 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.
What is the importance of the protective position when using a pavlik harness?
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.
What is an alternative to a pavlik harness for treatment of acetabular dysplasia with or without subluxation? When would this alternative be recommened?
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.
