title: The breech presentation and the vertex presentation following an external version represent risk factors for neonatal hip instability.
abstract: The aim of this study was to evaluate the frequency and type of hip-joint instability and the frequency of hip dislocation requiring treatment in neonates who had been lying in the breech presentation and were delivered vaginally after an external version or by caesarean section, and to compare them with neonates who were naturally in the vertex presentation. Breech presentations without ongoing labour were subjected to an attempted external version and, in cases where this proved unsuccessful or where labour had started, to deliver by caesarean section. None of the breech presentations was vaginally delivered. The anterior-dynamic ultrasound method was used to assess the hip-joint status of the neonates. Out of 6,571 foetuses, 257 were in breech presentation after 36 wk of pregnancy. Sixty-two were vaginally delivered following an external version to vertex presentation and 195 were delivered by caesarean section, 75 of these following unsuccessful attempts to perform a version. Treatment for congenital hip-joint dislocation was performed on 0.2%. Out of the breech presentations, 1.0% of those delivered by caesarean section were treated, while in those with vaginal delivery following an external version the treatment frequency was 3.2%. No case of late diagnosed hip dislocation was recorded. Significant differences in frequency of hip-joint instability and treatment were found between (i) neonates delivered in breech presentation and those delivered with vertex presentation, (ii) infants delivered in vertex presentation, naturally or after successful version, and (iii) those delivered by caesarean section with or without attempted external version and those delivered with vortex presentation.
  
  
  CONCLUSIONS
  Breech presentation predisposes to increased hip instability. The instability is present prior to delivery and is certainly not a primary result of delivery forces. Both breech and vertex presentations following an external or spontaneous version should be considered as risk factors for neonatal hip instability.
authors.affiliation: Department of Paediatrics, Blekingesjukhuset, Karlskrona, University of Gothenberg, Sweden. john.andersson@ltblekinge.se
authors.forename: J E
authors.initials: JE
authors.lastname: Andersson
authors.forename: A
authors.initials: A
authors.lastname: Odén
mesh_terms: D001946:Breech Presentation; D002585:Cesarean Section; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging; D006801:Humans; D007231:Infant, Newborn; D007593:Joint Instability / Q000151:congenital / Q000209:etiology* / Q000628:therapy; D008297:Male; D015997:Neonatal Screening; D011247:Pregnancy; D012307:Risk Factors; D014463:Ultrasonography; D014710:Version, Fetal / Q000379:methods