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Developmental dysplasia of the hip (DDH)

Definition
  • A spectrum of disorders ranging from complete dislocation of the femoral head to a reduced hip joint with acetabular dysplasia



Types:
1. Complete hip dislocation.
2. Partial hip subluxation.
3. Hip dysplasia (incomplete development).

Risk factors:
  • family history - may reflect laxity of ligaments
  • Race- common in white 
  • Breech  presentation - Exaggerated positioning in acute flexion and adduction in utero may occur
  • Female sex - the presence of maternal relaxin in the fetal circulatory system
  • large fetal size 
  • First born child
Galeazzi's test
  • With the child is lying on a flat surface, flex the hips and knees so the heels rest flat on the table, just distal to the buttock . 
  • A dislocated hip is signaled by relative shortening of the thigh compared with the normal leg, as shown by the difference in knee height level. 
  • This test is almost always useless in children under 1 year of age and is negative if dislocation is bilateral.


Barlow's test
  • This is a provocative test that picks up an unstable but located hip; it is unsuitable for a dislocated hip. 
  • Thighs are gently grasped in the hand, with the thumb at the lesser trochanter and fingers at the greater trochanter . The hip is adducted slightly and gently pushed posteriorly with the palm. 
  • Detection of "pistoning," or the sensation of the femoral head subluxating over the posterior rim of the acetabulum, is a positive finding.



Ortolani's test:
  • This test detects hips that are already dislocated. 
  • The flexed limb is grasped as in Barlow's test. The hip is abducted while the femur is gently lifted with the fingers at the greater trochanter. 
  • In a positive test, there will be a sensation of the hip reducing back into the acetabulum. 







Clinical Manifestations

In newborn:
  • We can diagnose DDH in this period by positive Ortolani’s test or Barlow’s test.
  • Asymmetry of the skin fold may help, but its not specific. 
  • Shortening of the limb at this age doesn’t exist.
  • We cant use X-rays because the acetabulum and proximal femur are cartilaginous and wont be shown on X-ray.
  • USG is the best method to Dx.

In the early childhood:
  • Parents notice asymmetry of creases of groin, limitation of movement of affected hip or click every time hip is moved

In older children:
  • Complaints of limping, waddling gait (bilateral DDH), Trendelenburg’s gait (unilateral DDH), lumbar lordosis, limitation of hip abduction, etc…

X-ray

Von Rosen view:
hips abducted 45º & medially rotated.
Anteroposterior.
We draw a line through the central axis of the femoral shaft.
        in normal hip ( ossific nucleus )will be inside the acetabulum.
        in dislocated hip it will be above acetabulum.


Delayed development of ossific nucleus / smaller
Horizontal line of Hilgenreiner:
   drawn between upper ends of tri-radiate cartilage of the acetabulum.
Vertical line of Perkins:
  drawn from the lateral edge of the acetabulum vertical to horizontal line.
4 quadrants:
Normal hip: the ossification center of the femoral hip lower medial quadrant.
Dislocated hip: upper lateral quadrant.


Acetabular index:
    angle between horizontal line of Hilgenreiner and the line between the two edges of the acetabulum.
    normal hip 20º-300 
    dilocated or dysplastic hip ≥ 30º
Shenton’s line:
    semicircle between femoral neck and upper arm of obturator foramen, in dislocated hip this line is broken.

Treatment:


The earlier the better. 
Exact treatment depends on patient age at presentation and degree of involvement
Goal is to:
1.Flex and abduct hips.
2.Reduce femoral head and maintaining it.
Reduction can be achieved by closed manipulation , traction followed by closed reduction and opened reduction  
 maintenance can be done using plaster cast(frog leg or Batchelor) or splint (von Rosen’s splint)

  • Acetabular reconstruction procedure
  • Salter’s osteotomy
  • Chiari’s pelvic displacement osteotomy 
  • Pemberton’s pericapsular osteotomy

  • From (0-6 months)  
A dislocated hip at this age may spontaneously reduce over 2-3 weeks if the hip is held in a position of flexion. 
Reduction by closed manipulation and maintained with plaster cast or splint
  • From 6 months -2 year
Gentle closed reduction of the dislocation under a general anesthetic and maintenance of a located position for 2-3 months in a hip spica cast usually stabilize the joint
  • From the age of 2-6 years:

open reduction with osteotomy

  • 6-10 years

No treatment for bilateral
Open reduction with reconstruction for unilateral

  • After 10 years

Only indication for treatemnt is pain. If only one hip affected total hip replacement may be done.