Developmental Dysplasia of Hip

In brief

• Risk factors include breech delivery, female sex, and positive family history
• L > R, F > M, unilateral >bilateral: risk factors: female, mother or older sib with hip dysplasia
• Associated with other orthopedic abnormalities and several neuromuscular disorders
• Ortolani/Barlow for 1st 3-4 mos, then Galeazzi more sensitive
• Diagnose by exam, ultrasound under 4 months of age, and/or AP x-ray after 4 months of age
• Screen at each visit until age of 1 year!
• Incidence in BREECH FEMALES is 120/1000 so universal imaging is recommended
• Treatment methods include Pavlik Harness (if diagnosed before 6 months of age), closed reduction with spica cast (generally 6-18 mos), or surgical release of tight adductors with open reduction (generally > 18 mos)

Discussion

• ranging from minimal instability to irreducible dislocation; detectable at birth or shortly thereafter; may not present in neonatal period. Screen at each visit until age of 1 year!
• Idiopathic vs teratogenic types:
  • Idiopathic: more common, + family Hx, variable severity, abnormal intrauterine positioning or restriction of fetal movement in utero. The relaxing effects of hormones on soft tissue during pregnancy may also contribute, hx of breech not uncommon (these patients often exhibit generalized ligamentous laxity)
  • Teratogenic: more severe, caused by germ plasm defect, occurs early in fetal development, malformation of both femoral head and acetabular socket. Associated congen anomalies common: clubfoot, congenital torticollis, metatarsus adductus, infantile scoliosis.
• caused by lack of acetabular depth, ligamentous laxity, and/or intrauterine breech posn
• 17-50% of all CHD occurs in infants born after breech
• detectable dysplasia: incidence 1-2/1000 live births; but varies by race: caucasians 1/60, complete disloc 1/500. AA and asians less likely.
• L > R, F > M, unilateral >bilateral: risk factors: female, mother or older sib with hip dysplasia
• more common in infants w/ other ortho abnormalities ie torticollis (in 10-20%), clubfoot, metatarsus adductus (in 1%)
• early dx/tx necessary to ensure nl hip anatomy and function
• Other signs suggestive of DDH: asymmetry of thigh/gluteal folds (may in present in 10% of nl), galeazzi test (femoral shortening) aka Allis test (these signs are absent if B/L pathology). A later sign is limited hip abduction.
• A dislocated hip will be held adducted and externally rotated
• Hip XR difficult to interpret in nbn period; femoral head and acetabulum are cartilaginous at birth; significant calcification to permit adequate XR occurs at 3-4 m/o. Femoral head is usually supero-lateral to acetabulum, which is usually shallow

Treatment

• Keep legs abducted and hips, knees flexed, so developing head of femur is kept in acetabulum. In 1st 6 months of life use Pavlik harness, Frejka splint. Use of 2-3 diapers to keep hips abducted, is not recommended; not enough stabilization.
• Between 6-18 mos of age, gentle closed reducation and immobilization in spica cast w or wo surgical release of the contracted iliopsoas and adductor muscles.
• After age 18 mos, reduction by manipulative measures is difficult due to contractures; open reduction. In teratogenic dislocation, underlying maldevelopment makes the outcome less satisfactory, even w optimal management.
• Failure of concentric reduction or complications ie avascular necrosis of femoral head (from overzealous attempts at closed reduction in long-standing cases), may result in life long disability: pain/stiff hip, antalgic, lurching gait, shortening of limb.