Medicine

Developmental Dysplasia of the Hip (DDH)

A concise overview of developmental dysplasia of the hip (DDH) in children and its treatment.
 

Developmental dysplasia of the hip is abnormal development of the hip resulting in dysplasia and subluxation or dislocation of the hip joint.

Etiology

Its caused by:

  • Musculoskeletal:
    • Ligamentous laxity
    • muscular underdevelopment
    • abnormal shape of acetabular roof

Clinical Features

Presents as a spectrum which incldue:

  • Dislocated femoral head completely out of acetabulum
  • Dislocatable head in socket
  • Head subluxates out of joint when provoked
  • Dysplastic acetabulum: more shallow and more vertical than normal
  • Painless (if pain full, think dislocation)

Physical Examination

This is a clinical diagnosis. You will find:

  • Limited abduction of the flexed hip (< 50 - 60 degrees)
  • Affected leg shortening results in asymmetry in skin folds and gluteal muscles
  • Wide perineum
  • Barlows Test positive (Test to see if hips are dislocatable):
  1. Flex hips and knees at 90 degrees and grasp thigh
  2. Fully adduct hips
  3. Push posteriorly and try to dislocate
  • Ortolani’s Test positive (Test to see if hips are dislocated)
  1. Initial position as Barlows test but try to reduce hips with finger tips during ABDUCTION
  2. Postive if palpable clunk is felt (not heard) when hip reduced.
  • Galeazzi’s sign
  1. Knees are unequal height when hips and knees are flexed
  2. Dislocated hip will be on side of lower knee
  3. Difficult to test on a child less than 1 year old
  4. Do Trendelenburg test and GAIT to confirm if older than 2 years.

Investigations

Do ultrasound in first few months to view cartilage (bones not calcified until 4-6 months. After 3 months, follow up with radiograph
Xray signs at 4-6 months are:

  • false acetabulum
  • acetabular index >25 degrees

    Acetabular Index: Angle between Hilgenreiner’s line and from the Triradiate cartilage to the point on the lateral margin of the acetabulum.
    Triradiate Cartilage: Y-shaped epiphyseal plate at junction of the ilium, ischium and pubis.
    Perkins line: Line through the lateral margin of the acetabulum,perpendicular to the helgenreiners line.
    Helgenreiners line: Line running through the triradiate cartilages.
    Shentons line: Arced line along the inferior border of the femoral neck and superior margin of the obturator

  • Broken shenton’s line
  • Femoral Neck above above Hilgenreiners line.
  • Ossification center outside of inner lower quadrant (quadrants formed by the intersection of Helgenreiner’s line and Perkins line)

Predisposing Factors

Remember the 5 F’s of DDH:

  • Family history
  • Female
  • Frank Breech
  • First Born
  • leFt Hip (pressed against maternal spinal vertebra)

Treatment

Age dependent:

  • 0-6 months: Reduce hip using a Pavlik harness to maintain abduction and fexion

  • 6-18 months: Reduction under general anesthesia, place in Hip Spica cast for 2-3 months if pavlick harness fails
  • 18 months: Open reduction; pelvic and/or femoral osteotomy

Complications:

  • Redislocation
  • Inadequate reduction
  • Stiffness
  • Avascular Necrosis of femoral head