Congenital Hip Dislocation

1. Epidemiology: Classic Congenital Hip Dislocation
   1. Incidence
      1. Hip subluxation at birth: 1%
      2. Hip dysplasia in infants: 0.1 to 0.3%
   2. Girls 9 times more often affected than boys
   3. Usually unilateral, but bilateral is common
2. Risk Factors
   1. Breech Presentation
   2. Female gender
   3. Family History (positive in up to one third of cases)
      1. One affected sibling: 6% risk
      2. One affected parent: 12% risk
      3. One affected sibling and one affected parent: 36%
   4. Firstborn
   5. Oligohydramnios
3. Pathophysiology
   1. Femoral head dislocates from acetabulum
   2. Results from Acetabular Dysplasia (shallow acetabulum)
      1. Results in subluxed, dislocated or unstable hip
   3. Left hip is affected in 60% of cases
      1. Remainder are right (20%) and bilateral (20%)
4. Types
   1. Classic Congenital Hip Dislocation
   2. Congenital Abduction Contracture of the Hip
   3. Teratologic Congenital Hip Dislocation
      1. Severe, prenatal fixed dislocation
      2. Associated with genetic and neuromuscular disorders
5. Associated Conditions
   1. Congenital Torticollis
   2. Breech Presentation in utero
   3. First degree relative with hip dysplasia history
   4. Clubfoot
6. Symptoms
   1. Painless limp in toddler (best if diagnosed earlier)
7. Signs: Classic Congenital Hip Dislocation
   1. Dislocation and Relocation maneuvers
      1. Useful only in first 3 months of life
      2. Repeat in 2 weeks if equivocal
      3. Tests
         1. Ortolani Test (relocate hip into acetabulum)
         2. Barlow's Test (attempt to sublux unstable hip)
   2. Pelvis symmetry
      1. Galeazzi's Sign (compare the 2 femur lengths)
      2. Observe for asymmetric skin folds
8. Imaging
   1. Dynamic Hip Ultrasound (infant aged 1-6 months)
      1. Diagnostic for Congenital Hip Dislocation
      2. Evaluates for subluxation and reducibility
      3. High false positive rate <6 weeks
   2. Hip XRay
      1. Not diagnostic for dislocation until >6 months
         1. Femoral head not calcified under age 4-6 months
         2. Diagnostic for Acetabular Dysplasia
            1. Abnormal acetabular fossa will be seen
      2. Evaluated with reference lines drawn over AP XRay
         1. Hilgenreiner's Line
            1. Horizontal line through triradiate cartilages
         2. Perkin's Line
            1. Vertical line along each lateral acetabulum
         3. Shenton's Line
            1. Femoral neck medial border
            2. Superior border of obturator foramen
9. Course: Classic Congenital Hip Dislocation
   1. Many unstable hips at birth stabilize by 5 days
10. Management: Classic Congenital Hip Dislocation
    1. Management indicated for hip instability beyond 5 days
    2. Step 1: Pavlik Harness
       1. Indicated as first-line if age <6 months
       2. Start with harness trial for 3-4 weeks
       3. Splints hips in flexed and abducted position
       4. Long-term effect: 95% (80% if frank dislocation)
       5. Ultrasound should demonstrate reduction at 3 weeks
          1. Reduced: Continue harness for >6 weeks
          2. Not Reduced: Go to Step 2
    3. Step 2: Closed Reduction and Casting by Orthopedics
       1. Indications
          1. No reduction with Pavlik Harness in 3-4 weeks
          2. Children over age 6 months
       2. Attempted closed reduction under arthrogram
       3. Hip Spica Casting for 12 weeks
       4. Positioning confirmed by post-op MRI or CT
    4. Step 3: Surgical Open reduction
       1. Indicated in refractory cases
       2. Requires multi-step procedure
          1. Tendon lengthening
          2. Clearing tissues obstructing relocation
          3. Tightening hip capsule
          4. Osteotomy if performed after age 18 month
       3. Complicated by re-disclocation, osteonecrosis
11. Prognosis
    1. Delayed treatment risks worse outcomes
    2. Monitor children with imaging until skeleton mature
12. Complications
    1. Premature arthritis of the hip as early as late teen
13. References
    1. (2006) Pediatrics 117:898-902
    2. Harding (1997) J Pediatr Orthop 17:1149-52
    3. Storer (2006) Am Fam Physician 74(8):1310-6
    4. Vitale (2001) J Am Acad Orthop Surg 9:401-11