Developmental Dysplasia of the Hip
Developmental Dysplasia of the Hip (DDH) is a condition where the hips of infants stabilise in a dislocated or dysplastic position, requiring intervention.
Approximately 1 to 2 in every 1000 babies are affected. DDH may not be immediately apparent at birth and can progress in the first few months. A normal hip ultrasound in infancy does not preclude the later development of DDH. The condition has a higher incidence in female breach babies. The severity and clinical manifestations of DDH vary with the child’s age, and early detection is key for simpler and more effective treatment, improving long-term outcomes.
The reliability of physical examination for DDH changes as the child grows. Routine DDH assessment is recommended in the first 18 months of life, specifically at 1, 2, 4, 6, 12, and 18 months.
History taking should include risk factors such as breech delivery or presentation, family history of DDH, and other indicators like female sex, high birth weight (>4kg), post-term delivery (>42 weeks), firstborn babies, and the presence of intrauterine packaging deformities. Packaging deformities include plagiocephaly, torticolis, and foot deformities.
Clinical examination should be conducted when the child is calm, utilizing age-appropriate techniques:
For Infants Aged 0 to 3 Months
- Barlow Test: Involves abduction and adduction of the flexed hip with posterior and anterior pressure, respectively. A positive test is indicated by a palpable clunk as the femoral head exits the acetabulum.
- Ortolani Test: Involves abduction of the flexed hip while lifting the leg anteriorly. A clunk indicates a positive test.
For Infants Aged > 3 Months
- Restricted Abduction: Limited unilateral hip abduction, less than 60°, is a sensitive sign. Perform gradually and it may need to be repeated several times to ensure accuracy.
- Leg Length Discrepancy: Assessed in the prone position and using the Galeazzi test.
- Asymmetrical Skin Folds: Checked in the prone position, although asymmetry alone does not diagnose DDH.
For older walking children, signs such as toe-walking, limp, increased lumbar lordosis, or a waddling gait may indicate DDH.
Imaging According to Child's Age
- < 6 Weeks: Ultrasound is recommended at 6 weeks due to immature hip development earlier.
- 6 Weeks to 4 Months: Ultrasound is the preferred imaging.
- 4 to 6 Months: Consider ultrasound and/or X-ray, consulting with a radiologist or orthopedist.
- ≥ 6 Months: X-ray is preferred as ossification obscures ultrasound imaging.
Imaging is indicated for normal hips with risk factors (especially if 4 or more risk factors - female baby, large baby, overdue, intrauterine packaging deformities, firstborn), subluxatable hips, or if soft signs of DDH with ongoing concern.
For Patients Aged < 6 Months with Normal Imaging
- Continue regular clinical monitoring.
- Advise on safe swaddling.
- Consider an urgent referral for persistent concerns or surveillance AP pelvis X-ray at 12 months if risk factors are present.
For Normal X-ray and Continued Symptoms
- Investigate other causes of limited hip abduction, short leg, or limp.
Request Urgent Review by a Specialist If:
- Positive Ortolani or Barlow's test with a distinct hip clunk.
- Leg length discrepancy, unilateral toe walking, or unilateral reduced hip reduction.
- Abnormal imaging findings.
- Persistent concerns upon re-examination.
Explaining Treatment to Parents
- Children < 6 months usually managed with bracing.
- Diagnosis from 6 to 12 months might require manipulation under anesthesia and a plaster hip spica.
- Children diagnosed at ≥ 12 months often need surgical intervention.
Request urgent review by a paediatrician or paediatric orthopaedic surgeon in cases of dislocated or dislocatable hip, leg length discrepancy, unilateral toe walking, abnormal imaging, or ongoing concerns