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Paediatric Orthopaedics
Neonatology
General Practice

Developmental Dysplasia of the Hip (DDH)

High EvidenceUpdated: 2025-12-26

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Red Flags

  • Late Presenter (>6 months) -> High risk of AVN and complex surgery
  • Stuck Pavlik -> If not reducing, ABANDON to prevent AVN
  • Femoral Nerve Palsy -> Pavlik strap too tight (flexion)
Overview

Developmental Dysplasia of the Hip (DDH)

1. Clinical Overview

Summary

Developmental Dysplasia of the Hip (DDH) encompasses a spectrum of pathology from Acetabular Dysplasia (shallow socket) to Subluxation and frank Dislocation. It is the most common orthopaedic disorder in newborns. Early detection via the NIPE (Newborn and Infant Physical Examination) and Ultrasound Screening is critical. The "Golden Window" for treatment is <6 months, where a Pavlik Harness is 90% successful. Late diagnosis (>6 months) requires closed or open reduction and carries a significantly worse prognosis for long-term arthritis. [1,2,3]

Key Facts

  • The 4 Fs (Risk Factors): Female (6:1), First Born (Tight uterus), Feet First (Breech), Family History.
  • Screening: All babies get clinical check (Ortolani/Barlow). Risk factors get an Ultrasound at 6 weeks.
  • Pavlik Harness: A dynamic splint that holds the hip in Flexion and Abduction (The "Human Position"). It steers the femoral head into the acetabulum, stimulating it to deepen.

Clinical Pearls

"Ortolani is the GOOD one": Ortolani starts "Out" and puts it "In" (Reduces). This is a palpable "Clunk".

"Barlow is the BAD one": Barlow starts "In" and pushes it "Out" (Dislocates). It tests for instability.

"Asymmetry is key": In an older infant (>3 months), the clunk disappears. Look for Asymmetrical Skin Creases (groin/thigh) and Limited Abduction (the most sensitive sign in older kids).

2. Epidemiology

Demographics

  • Incidence: 1-3 per 1000 live births (Dislocated). 10 per 1000 (Dysplasia).
  • Gender: Female > Male (6:1). (Estrogen sensitivity relaxes ligaments).
  • Side: Left > Right (3:1). (Left hip is pressed against mother's spine in LOA position).
3. Pathophysiology

Mechanism

  • Mechanical: Intra-uterine packaging (Breech, Oligohydramnios) moulds the hip into a dislocated position.
  • Ligamentous: Maternal Relaxin crosses placenta, making fetal ligaments lax.
  • Acetabular Dysplasia: Without the concentric pressure of the femoral head, the acetabulum fails to deepen. It remains shallow and vertical (high Acetabular Index).

Graf Classification (Ultrasound)

  • Type I: Normal. (Alpha >60).
  • Type IIa: Physiologically immature (<3 months).
  • Type IIb: Dysplastic (>3 months).
  • Type III: Subluxed.
  • Type IV: Dislocated.
4. Clinical Presentation

Neonate (<3 months)

Infant (>3 months)

Walking Child

Ortolani Test
Reducing a dislocated hip. (Flex hips 90, Abduct, lift Trochanter). "CLUNK".
Barlow Test
Provocative. (Adduct and push posterior). "CLUNK" (dislocates).
5. Investigations

Ultrasound (<6 months)

  • Gold Standard before ossification.
  • Graf Method: Measures Alpha angle (bony roof) and Beta angle (cartilage roof).
  • Indication: Positive Ortolani/Barlow OR Risk Factors (Breech/Family Hx).

X-Ray Pelvis (>6 months)

  • Used once femoral head ossifies (4-6 months).
  • Perkin's Line: Vertical line adjacent to acetabulum.
  • Hilgenreiner's Line: Horizontal through triradiate cartilage.
  • Normal: Head should be in the Lower Inner Quadrant.
  • Acetabular Index (AI): Slope of the roof. Should be <25-30 degrees. >30 is dysplastic.
  • Shenton's Line: Continuous arc from femoral neck to pubic rami. Disruption = Dislocation.
6. Management Algorithm
                 AGE AT DIAGNOSIS?
             ┌──────────┴──────────┐
        &lt; 6 MONTHS            > 6 MONTHS
             ↓                     ↓
       PAVLIK HARNESS         CLOSED REDUCTION
      (Dynamic Splint)        (Hip Spica Cast)
       (90% Success)               ↓
             ↓                  FAILED?
          FAILED?                  ↓
             ↓                 OPEN REDUCTION
      CLOSED REDUCTION        (Surgery) +/-
      (Exam Under Anaesthetic)  OSTEOTOMY
7. Management Protocols

1. Pavlik Harness (0-6 months)

  • Mechanism: Holds hip in 100° Flexion and Abduction. Does NOT force reduction; allows head to settle in.
  • Duration: 6-12 weeks usually.
  • Safety Zones (Ramsey):
    • Avoid excessive Flexion: Compromises Femoral Nerve.
    • Avoid excessive Abduction: Causes Avascular Necrosis (AVN).

2. Closed Reduction (6-18 months)

  • Baby is too big for Pavlik.
  • Procedure: Contrast arthrogram (check reduction) -> Manipulation -> Hip Spica Cast.
  • Duration: 3 months in cast.

3. Open Reduction (>18 months)

  • Procedure: Surgical removal of obstacles (Pulvinar fat, Inverted Limbus, Tight Psoas).
  • Osteotomy:
    • Femoral: Shortening/Derotation (VDRO) to point the head into the socket.
    • Pelvic (Salter/Pemberton): Cutting the pelvis to redirect the roof over the head.
8. Complications

Avascular Necrosis (AVN)

  • Incidence: 1% (Pavlik) to 5-10% (Surgery).
  • Cause: Excessive abduction cuts off the Medial Circumflex Femoral Artery.
  • Result: Growth arrest of the femoral head, deformity (Perthes-like changes).

Residual Dysplasia

  • Even if reduced, the acetabulum may remain shallow.
  • Leads to early Osteoarthritis in 20s/30s.
9. Evidence & Guidelines

The International Hip Dysplasia Institute (IHDI)

  • Classification system for severity based on station of the femoral head.

AAOS Guidelines (2014)

  • Strong Recommendation: Early screening with physical exam.
  • Moderate Recommendation: Ultrasound for high-risk infants (Breech/FHx) at 6 weeks.
  • Strong Recommendation: Pavlik harness as first line for reducible DDH.
10. Patient Explanation

What is DDH?

The hip is a ball-and-socket joint. In DDH, the socket (cup) doesn't grow deep enough, so the ball keeps slipping out. It's like an egg trying to sit in a teaspoon instead of an eggcup.

Why the harness?

The Pavlik harness is a set of soft straps. It holds the baby's legs in a "frog" position. This pushes the ball firmly into the socket. The pressure tells the body to grow a deeper cup. It works 9 times out of 10 without any surgery.

What if it doesn't work?

If the harness fails, or if the baby is diagnosed late, we might need a small operation or a plaster cast (Spica) to hold the hip in place while it grows.

11. References
  1. Pavlik A. The functional method of treatment using a harness with stirrups as the primary method of treatment for congenital dysplasia of the hip. Clin Orthop Relat Res. 1992.
  2. Graf R. Classification of hip joint dysplasia by means of sonography. Arch Orthop Trauma Surg. 1984.
12. Examination Focus (Viva Vault)

Q1: Describe the structures obstructing reduction in DDH. A: The "Inverted Limbus" (Labrum), The "Pulvinar" (Fat pad), The "Transverse Acetabular Ligament", a tight "Psoas Tendon", and a tight "Capsule" (Hourglass constriction).

Q2: What are the risks of the Pavlik Harness? A: Femoral Nerve Palsy (if flexion >120°), Avascular Necrosis (if abduction is forced >60°), and Skin breakdown.

Q3: When do you perform an ultrasound vs an X-ray? A: Ultrasound is used <4-6 months (before the femoral head ossifies - cartilage is invisible on X-ray). X-ray is used >6 months once the ossific nucleus appears.

(End of Topic)

Last updated: 2025-12-26

At a Glance

EvidenceHigh
Last Updated2025-12-26

Red Flags

  • Late Presenter (&gt;6 months) -> High risk of AVN and complex surgery
  • Stuck Pavlik -> If not reducing, ABANDON to prevent AVN
  • Femoral Nerve Palsy -> Pavlik strap too tight (flexion)

Clinical Pearls

  • **"Ortolani is the GOOD one"**: Ortolani starts "Out" and puts it "In" (Reduces). This is a palpable "Clunk".
  • **"Barlow is the BAD one"**: Barlow starts "In" and pushes it "Out" (Dislocates). It tests for instability.
  • Male (6:1). (Estrogen sensitivity relaxes ligaments).
  • Right (3:1). (Left hip is pressed against mother's spine in LOA position).

Guidelines

  • NICE Guidelines
  • BTS Guidelines
  • RCUK Guidelines