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Developmental Dysplasia of the Hip

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Developmental Dysplasia of the Hip
Sunny Gupta
Basics
Developmental dysplasia of the hip (DDH) is the most common disorder of the hip in children.
Description
  • Dysplasia refers to an acetabulum that is shallow or underdeveloped.
  • Subluxation refers to a femoral head that is not centered within the acetabulum.
  • Dislocation refers to a femoral head that is completely out of the acetabulum.
  • Teratologic dislocation refers to a femoral head that is in a fixed dislocated position usually associated with a genetic, developmental, or neuromuscular disorder.
  • An unstable hip refers to a femoral head that can be subluxed or dislocated on physical examination.
  • DDH refers to a wide spectrum of hip disorders from mild underdevelopment of the acetabulum to frank teratologic dislocation of the femoral head from the acetabulum.
Epidemiology
Incidence
  • Incidence varies with gender, age, and race.
  • Incidence of hip dysplasia is 0.5–2% of live births; however, true dislocation occurs in 0.1–0.2% of live births.
  • Late dysplasia, subluxation, and dislocation occur in 0.04% of children.
Risk Factors
  • Predominant race: More common in Caucasians of European descent; rare in African Americans
  • Predominant gender: Females > Males (6:1)
  • Birth order: Increased risk with firstborns.
  • Family history: Very strong risk factor
  • Risk ∼13% with 1 parent with hip dysplasia and 35% with affected parent and sibling.
  • Intrauterine factors: Increased risk with breech presentation and oligohydramnios
General Prevention
  • There is no true way to prevent occurrence.
  • Early diagnosis is key to management.
  • Thorough examination of hips of newborns and infants is the mainstay of early diagnosis.
Etiology
  • Caused by any mechanism that prevents femoral head from being positioned correctly within the acetabulum, resulting in a shallow acetabulum.
  • Firstborn
  • Intrauterine factors:
    • Abnormal intrauterine positioning: Breech presentation positions hip in such a way that the femoral head is forced out of the acetabulum.
    • Oligohydramnios
  • Underlying ligamentous laxity
  • Collagen-vascular disorders
  • Infection
  • Environmental: Culture-associated neonatal swaddling
  • Congenital:
    • Arthrogryposis
    • Lumbosacral agenesis
    • Spina bifida
    • Neonatal Marfan syndrome
    • Fetal hydantoin syndrome
    • Larsen syndrome
Commonly Associated Conditions
Commonly associated with other “packaging” problems, such as torticollis (20% coexistence) and metatarsus adductus (10% coexistence)
Diagnosis
History
  • Determine risk:
    • Breech delivery?
    • Female?
    • Firstborn?
    • Family history?
    • Race?
  • Is the baby moving both lower extremities symmetrically?
  • Any abnormal position of lower extremities noticed by parents?
Physical Exam
  • All infants require clinical screening by primary care provider who has experience in examining the hip.
  • Examine patient in supine position.
  • Every attempt should be made to examine the infant when he or she is not crying to avoid tensing of lower extremity muscles.
  • Observe for signs of asymmetries:
    • Decrease in abduction of hip with adduction contracture
    • Asymmetric gluteal, anterior upper thigh, and popliteal skin folds
    • Galeazzi sign: Apparent femoral shortening with hips and knees flexed together
  • Ortolani test:
    • Abduction and external rotation of hip with examiner's middle finger over greater trochanter
    • Palpable clunk is positive sign produced by reduction of dislocated hip.
  • Barlow test:
    • Adduction and internal rotation of hip
    • Palpable clunk is positive sign as hip dislocates.
  • Examination may be normal initially despite the presence of hip dysplasia. Consequently, hip evaluation should be performed as part of neonatal physical examination through 4 mos of age.

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Diagnostic Tests & Interpretation
Lab
  • False-positive results: Hip clicks will be present in 10% of infants; only a small percentage will have hip dysplasia.
  • Overdiagnosis is a problem because avascular necrosis of femur can occur (rarely) as a result of therapeutic interventions.
Imaging
  • X-rays:
    • Not useful prior to 4 mos, when the femoral head epiphysis ossifies and acetabular parameters are better defined.
    • Various reference lines (Hilgenreiner's, Shenton's, and Perkin's) and angles (acetabular index) are useful to detect frank dislocation.
  • US:
    • Most sensitive and effective form of screening
    • Recommended to screen with US starting at age 4–6 wks in patients with risk factors, persistent clunk on hip exam, or asymmetric hip exam.
    • Static and dynamic imaging (with Barlow and Ortolani maneuvers) to assess femoral head displacement
    • Useful in monitoring progress of therapy
    • Requires experienced ultrasonographer
  • CT scan and MRI are not useful in diagnosis.
Treatment
  • Subluxation at birth often resolves spontaneously and therefore may be observed for 3 wks.
  • Indication for treatment: Subluxation of hip persists beyond 3 wks, confirmed on physical exam or US. Refer to a pediatric orthopedist.
  • Pavlik harness:
    • Indicated for infants from ages 3 wks to 6 mos
    • Applied by orthopedist; hips positioned in flexion and abduction
    • Requires weekly evaluation of straps and radiologic confirmation of hip reduction; if hip is stable at 2 wks, reevaluation every 2 wks.
    • Gradually weaned as hip stability continues
    • Duration of treatment: 3 mos after hip stability achieved
  • Hip spica cast:
    • Indicated for children from ages 6–18 mos
    • Applied by orthopedist under general anesthesia; hips positioned in flexion and abduction with cutouts for perineal care
    • Cast changes every 6 wks
    • Duration of treatment: 3–4 mos
  • Open reduction:
    • Indicated if closed reduction fails or excess abduction (>60 degrees) required for concentric reduction
    • Corrects barriers to reduction, and safely increases stability
  • Femoral/pelvic osteotomies:
    • Indicated if all prior closed and open reductions fail
    • Usually considered in children from ages 18–36 mos
Ongoing Care
Prognosis
If diagnosed early, prognosis is uniformly excellent.
Complications
  • Missed early diagnosis can result in more complicated management and less favorable outcome.
  • Failed reduction and redislocation
  • Osteonecrosis of femoral head
  • Hip labral pathology in adolescence or adulthood
  • Osteoarthritis in adulthood
Additional Reading
Beaty JH. Congenital and Developmental Anomalies of Hip and Pelvis. Campbell's Operative Orthopaedics. 10th ed. 2003: Mosby, Inc. 1079–1117.
Bennet GC. Screening for congenital dislocation of the hip. J Bone Joint Surg Br. 1992;74:643–644.
Cotillo JA, Molano C, Albiñana J. Correlative study between arthrograms and surgical findings in congenital dislocation of the hip. J Pediatr Orthop B. 1998;7:62–65.
Darmonov AV, Zagora S. Clinical screening for congenital dislocation of the hip. J Bone Joint Surg Am. 1996;78:383–388.
Guille JT, Pizzutillo PD, MacEwen GD. Development dysplasia of the hip from birth to six months. J Am Acad Orthop Surg. 2000;8:232–242.
Vitale MG, Skaggs DL. Developmental dysplasia of the hip from six months to four years of age. J Am Acad Orthop Surg. 2001;9:401–411.
Codes
ICD9
  • 718.75 Developmental dislocation of joint, pelvic region and thigh
  • 754.30 Congenital dislocation of hip, unilateral
  • 755.63 Other congenital deformity of hip (joint)


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