Summary

Developmental Dysplasia of the Hip (DDH) encompasses a spectrum of hip disorders in the neonate/infant, ranging from mild acetabular dysplasia -> subluxation -> complete dislocation. It is a "packaging disorder" often associated with Torticollis and Metatarsus Adductus. The etiology is multifactorial (Genetic + Mechanical). Early detection via the NIPE exam (Barlow/Ortolani tests) is critical, as the Pavlik Harness is 90% effective if started <6 months. Late diagnosis leads to complex surgery (Osteotomies) and early onset osteoarthritis in young adults. [1,2,3]

Key Facts

• The 6 Risk Factors (The 6 Fs):
  1. Female (6:1 ratio).
  2. First Born (Tighter uterus).
  3. Family History (10-20% risk).
  4. Feet First (Breech - 20% risk).
  5. Fluid (Oligohydramnios - less room to move).
  6. Fat (High birth weight/Macrostomia).
• Barlow vs Ortolani:
  • Barlow: Bad (Dislocates the hip).
  • Ortolani: Open (Reduces the hip - "Clunk").

Clinical Pearls

"Clunk not Click": A hip "click" is common and usually benign (fascia snapping). A "clunk" is the feeling of the femoral head reducing into the socket. It is pathological.

"The Golden Period": The hip has huge remodeling potential in the first 6 months. A dysplastic acetabulum will deepen rapidly if the head is held concentrically reduced. After 18 months, this potential drops significantly.

"Breech is Big": A breech baby with a normal exam STILL needs an Ultrasound at 6 weeks. The exam is not perfect (especially if the hip is dislocated and irreducible, Ortolani will be negative).

1. Barlow Test (Provocative)

• Action: Adduct the hip and push Posteriorly.
• Result: The head slips OUT of the socket.
• Meaning: The hip is Dislocatable.

2. Ortolani Test (Reductive)

• Action: Abduct the hip and lift the Trochanter Anteriorly.
• Result: A palpable "Clunk" as the head slips IN.
• Meaning: The hip was Dislocated, but is Reducible.

3. Limited Abduction

• In a reduced but dysplastic hip, the adductors contract. Abduction is often <60 degrees.

                 DDH DIAGNOSIS
                        ↓
                       AGE?
             ┌──────────┴──────────┐
        < 6 MONTHS            > 6 MONTHS
             ↓                     ↓
       PAVLIK HARNESS       EXAM UNDER ANAESTHETIC (EUA)
    (Flexion/Abduction)            ↓
             ↓             CLOSED REDUCTION POSSIBLE?
          FAILS?           ┌───────┴────────┐
             ↓            YES               NO
      CLOSED REDUCTION    ↓                 ↓
        + SPICA CAST     HIP SPICA      OPEN REDUCTION
                                       (+/- Osteotomy)

The Pavlik Harness

• Mechanism: Holds the hip in Flexion (100 deg) and Abduction (45 deg).
• Principle: Directs the femoral head into the acetabulum, stimulating deep growth.
• Duration: 6-12 weeks. Ultrasound monitoring every 2 weeks.
• Success: 90-95% for dysplastic/subluxated hips.
• The Ramsey Safe Zone:
  • Too much Flexion: Femoral Nerve Palsy.
  • Too much Abduction: Avascular Necrosis (AVN).
  • Too little Flexion: Re-dislocation.

1. Closed Reduction & Spica

• Indication: Failed Pavlik or Late presentation (6-18 months).
• Technique: Manipulation under anaesthetic + Adductor Tenotomy (to release tight muscle). Plaster cast from chest to ankle (Spica).
• Duration: 3-4 months in cast.

2. Open Reduction

• Indication: Failed closed reduction or Child >18 months.
• Technique: Surgical opening of the joint. Removal of blocks (Pulvinar, Inverted Limbus).
• Osteotomy:
  • Femoral: Shortening/Derotation (to take tension off).
  • Pelvic (Salter/Pemberton/Dega): Cutting the pelvic bone to rotate the acetabulum over the head (re-orientating the roof).

American Academy of Pediatrics (2016)

• Screening: Avoid universal ultrasound (high false positives). Use selective ultrasound for risk factors (Breech, Family Hx) or abnormal exam.

International Hip Dysplasia Institute (IHDI)

• Standard for Pavlik application and monitoring.
• Emphasizes the "Safe Zone" concept.

What is wrong with the hip?

The hip is a ball and socket joint. In your baby, the socket is too shallow, like a saucer instead of a cup. The ball keeps slipping out.

Why the harness?

The harness holds the legs in a "frog" position. This pushes the ball deep into the socket. Because babies grow so fast, the socket detects this pressure and grows deeper around the ball, fixing itself.

Does it hurt?

No. Babies adapt very quickly. You can still hold and feed them normally.

What if we do nothing?

The child will walk with a limp. But the main problem is pain later in life. A shallow hip wears out very fast. They might need a hip replacement by age 30.

Q1: What are the borders of the "Safe Zone" in a Pavlik Harness? A: The zone between maximum Abduction (risk of AVN) and the point of Redislocation (Adduction). It allows 30-60 degrees of safe movement.

Q2: What are the 4 common obstacles to reduction in open surgery? A: 1. Inverted Limbus (Labrum). 2. Hypertrophied Ligamentum Teres. 3. Pulvinar (Fat pad). 4. Tight Iliopsoas tendon. 5. Transverse Acetabular Ligament.

Q3: Describe Shenton's Line. A: A continuous radiographic arc drawn along the superior border of the obturator foramen and the medial aspect of the femoral neck. In DDH, the femoral head is superior/lateral, breaking the arc.

Q4: Why are females more affected? A: Ligamentous laxity due to sensitivity to maternal hormones (Relaxin/Estrogen) which cross the placenta.

(End of Topic)