Impediments to Reduction in DDH

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- See:
      - Pathogenesis of DDH:
      - Table I:

- Discussion:
    - soft-tissue impediments to adequate reduction include:
          - constriction of the joint capsule of hip: most important type of obstruction in older children;
          - contraction of the psoas tendon over acetabular inlet;
          - hypertrophy of the transverse acetabular ligament;
          - pulvinar, or the ligamentum teres;
              - as children reach walking age, hypertrophy of the ligament may
                      preclude hip reduction unless ligament is excised;
          - inverted neolimbus:
              - rare type of obstruction in DDH;
              - formed when dislocated femoral head is above or behind labrum;
              - lip of hypertrophied fibrocartilage may be infolded or everted;
              - may be adherent to hip capsule or supra-acetabular iliac wall;

- Infants Younger than 2 months;
    - when soft-tissue impediments prevent congruent reduction, positioning of
            hip in safe position (using Pavlik harness) may allow femoral head
            to overcome soft tissue impediments & become adequately reduced;
            - do not continue w/ this form of treatment for more than 4 weeks, since
                    process of acetabular dysplasia and soft tissue adaptive changes
                    will continue as long as hip remains dislocated;

- Infants Older than 2 months;
    - in children who are older than two months, spica cast may allow femoral
            head to overcome soft tissue impediments & become adequately reduced;
            - do not continue w/ this form of treatment for more than 4 weeks, since
                    process of acetabular dysplasia and soft tissue adaptive changes
                    will continue as long as hip remains dislocated;