title: Evaluation of risk factors in developmental dysplasia of the hip in children from multiple pregnancies: results of hip ultrasonography using Graf's method.
abstract: BACKGROUND
  The risk factors for developmental dysplasia of the hip (DDH) in infants from unifetal pregnancies are commonly known. Many of these factors also apply to multiple pregnancies. The aim of this paper was to evaluate the influence of selected, widely recognized DDH risk factors in unifetal pregnancy on the development of hip joints in infants from multiple pregnancies. The following risk factors were examined: family history of DDH, breech presentation, duration of pregnancy, birth weight and sex.
  
  
  METHODS
  The study included 200 newborns (400 hip joints) from multiple pregnancies. Ultrasound screening was performed using the Graf method during the first five postnatal days.
  
  
  RESULTS
  No cases of hip joint dysplasia requiring treatment were reported in the study group. The analysis of correlations between hip joint type according to Graf and the evaluated risk factors revealed the following results: type IIa hips were reported in 26 (6.91%) infants with a family history of DDH, one infant (1.22%) who demonstrated a breech presentation, 23 prematurely born infants (8.93%) and 28 infants with a mean birth weight of 2402 g. The correlations were not statistically significant. Type IIa hips were reported in 21 female infants (10.82%), which constituted a statistically significant correlation (p < or = 0.05).
  
  
  CONCLUSIONS
  Among the examined risk factors only the sex of the infant turned out to be significant for the development of hip joints in babies from multiple pregnancies. Type IIa hip joints were more common in female infants.No statistically significant correlations were found between Graf hip types and family history of DDH, breech presentation of the fetus, pregnancy duration under 38 weeks or the infant's birth weight.
authors.affiliation: Department of Orthopaedics and Paediatric Orthopaedics & Traumatology, Centre for Medical Post-Graduate Education (C.M.K.P) in Warsaw.
authors.forename: Andrzej
authors.initials: A
authors.lastname: Sionek
authors.forename: Jarosław
authors.initials: J
authors.lastname: Czubak
authors.forename: Maria
authors.initials: M
authors.lastname: Kornacka
authors.forename: Bartłomiej
authors.initials: B
authors.lastname: Grabowski
mesh_terms: D001946:Breech Presentation / Q000453:epidemiology; D005260:Female; D006618:Hip Dislocation, Congenital / Q000000981:diagnostic imaging* / Q000453:epidemiology*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening / Q000379:methods*; D010808:Physical Examination / Q000379:methods; D011044:Poland / Q000453:epidemiology; D011247:Pregnancy; D011272:Pregnancy, Multiple / Q000706:statistics & numerical data*; D016059:Range of Motion, Articular; D012307:Risk Factors; D018709:Statistics, Nonparametric; D014463:Ultrasonography