Developmental Dysplasia of the Hip (DDH)
Formerly known as Congenital Dislocation of the Hip (CDH), the term DDH is preferred because the hip may not be dislocated at birth but can develop dysplasia or dislocation later. It represents a spectrum from mild dysplasia to frank dislocation.
1. Risk Factors (The 5 Fs)
- Female: 8x more common in girls (ligament laxity due to maternal hormones).
- First Born: Tighter uterus.
- Feet First (Breech): Mechanical pressure.
- Family History: Genetics.
- Fluid (Oligohydramnios): Low amniotic fluid restricts movement.
2. Clinical Screening
Newborn (< 3 months):
- Barlow's Test: "Bad" test. Adduct and push posterior. If hip dislocates = Positive.
- Ortolani's Test: "Okay" test. Abduct and lift. If hip reduces with a "Clunk" = Positive.
Infant (> 3 months):
- Galeazzi Sign: Knee height discrepancy when hips/knees flexed.
- Asymmetrical Skin Folds: Thigh/gluteal folds.
- Limited Abduction: The most sensitive sign in older infants.
- Barlow's Test: "Bad" test. Adduct and push posterior. If hip dislocates = Positive.
- Ortolani's Test: "Okay" test. Abduct and lift. If hip reduces with a "Clunk" = Positive.
Infant (> 3 months):
- Galeazzi Sign: Knee height discrepancy when hips/knees flexed.
- Asymmetrical Skin Folds: Thigh/gluteal folds.
- Limited Abduction: The most sensitive sign in older infants.
3. Imaging
- Ultrasound: Gold standard for < 6 months (cartilage is not seen on X-ray).
- X-ray: Useful > 6 months when femoral head ossifies. Look for disruption of Shenton's Line.
4. Management
- 0-6 Months: Pavlik Harness (Flexion + Abduction). Keeps head in socket to stimulate development. Success rate > 90%.
- 6-18 Months: Closed Reduction + Hip Spica Cast.
- > 18 Months: Open Reduction + Osteotomy (Pelvic or Femoral).
25 Practice MCQs
Q1. The "Ortolani Test" is used to:
Answer: A). "O" for "Open" (Abduct) and "Out" to "In". A palpable clunk is felt.
Q2. Which is a major risk factor for DDH?
Answer: B). Breech position forces the hips into adduction.
Q3. The Barlow test involves:
Answer: A). Attempts to dislocate an unstable hip ("Barlow is Bad").
Q4. Ideally, the Pavlik harness holds the hip in:
Answer: A). Excessive abduction (Frog leg) risks AVN; excessive flexion risks Femoral Nerve palsy.
Q5. Imaging of choice for a 2-month-old infant with suspected DDH is:
Answer: B). Femoral head is cartilaginous and invisible on X-ray until 4-6 months.
Q6. Galeazzi (Allis) sign detects:
Answer: A). Seen when feet are placed on bed with knees flexed.
Q7. Shenton's Line is a continuous arc drawn along the:
Answer: A). The line is broken/disrupted in DDH.
Q8. The most serious complication of Pavlik Harness treatment is:
Answer: B). Caused by forced extreme abduction occluding vessels.
Q9. In a walking child with unilateral DDH, the gait is:
Answer: A). Bilateral DDH causes a Waddling Gait.
Q10. Acetabular Index (AI) on X-ray in a normal newborn is:
Answer: B). In DDH, the roof is steep/dysplastic, so AI is > 30-40 degrees.
Q11. Which sign is most reliable in a 6-month-old infant?
Answer: B). Adductor contracture develops, making the hip stiff. Barlow/Ortolani become negative.
Q12. Salter Osteotomy is:
Answer: A). Improves coverage of the femoral head.
Q13. "Telescoping" or "Pistoning" sign indicates:
Answer: A). The head is not contained in the acetabulum.
Q14. Triple diapering is:
Answer: B). Modern orthopedics recommends Pavlik harness, not extra diapers.
Q15. DDH is more common in the:
Answer: A). Due to LOA (Left Occiput Anterior) fetal position pressing left hip against maternal spine.
Q16. The "Safe Zone" of Ramsey refers to:
Answer: A). Treatment aims to keep the hip in this zone.
Q17. In DDH, the femoral head ossific nucleus appears:
Answer: A). Normally appears at 4-6 months.
Q18. The "Teardrop" figure on pelvic X-ray represents:
Answer: A). Widened or disrupted in DDH.
Q19. Femoral Nerve Palsy in Pavlik harness manifests as:
Answer: A). Due to hyperflexion. Check for active kicking at every visit.
Q20. Von Rosen splint is an alternative to:
Answer: A). A malleable metal splint (less common now).
Q21. Which muscle is typically shortened (contracted) in DDH?
Answer: A). Preventing abduction. Tenotomy is often needed.
Q22. The limbus is:
Answer: A). Pathological obstacle to closed reduction.
Q23. Is DDH painful in infants?
Answer: B). Pain usually develops in adolescence/adulthood if untreated.
Q24. In bilateral DDH, the perineum appears:
Answer: A). Due to lateral displacement of both femoral heads.
Q25. Screening for DDH is recommended:
Answer: A). Universal clinical screening is standard.
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