title: Valgus hip with high antetorsion causes pain through posterior extraarticular FAI.
abstract: BACKGROUND
  Valgus hips with increased antetorsion present with lack of external rotation and posterior hip pain that is aggravated with hip extension and external rotation. This may be the result of posterior femoroacetabular impingement (FAI).
  
  
  OBJECTIVE
  We asked whether (1) the range of motion (ROM); (2) the location of anterior and posterior bony collision zones; and (3) the prevalence of extraarticular impingement differ between valgus hips with increased antetorsion compared with normal hips and hips with idiopathic FAI.
  
  
  METHODS
  Surface models based on CT scan reconstructions of 13 valgus hips with increased antetorsion, 22 hips with FAI, and 27 normal hips were included. Validated three-dimensional collision detection software was used to quantify the simulated hip ROM and the location of impingement on the acetabular and the femoral sides.
  
  
  RESULTS
  Hips with coxa valga and antetorsion showed decreased extension, external rotation, and adduction, whereas internal rotation in 90° of flexion was increased. Impingement zones were more anteroinferior on the femur and posteroinferior on the acetabular (pelvic) side; and the zones were more frequently extraarticular, posterior, or to a lesser degree anterior against the inferior iliac spine. We found a higher prevalence of extraarticular impingement for valgus hips with increased antetorsion.
  
  
  CONCLUSIONS
  Valgus hips with increased antetorsion predispose to posterior extraarticular FAI and to a lesser degree anteroinferior spine impingement.
authors: Department of Orthopaedic Surgery, Inselspital, University of Bern, Freiburgstrasse, 3010, Bern, Switzerland, klaus.siebenrock@insel.ch.
authors: Klaus A
authors: KA
authors: Siebenrock
authors: Simon Damian
authors: SD
authors: Steppacher
authors: Pascal Cyrill
authors: PC
authors: Haefeli
authors: Joseph Michael
authors: JM
authors: Schwab
authors: Moritz
authors: M
authors: Tannast
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D060906:Coxa Valga / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D005260:Female; D057925:Femoracetabular Impingement / Q000150:complications / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006615:Hip / Q000000981:diagnostic imaging / Q000503:physiopathology; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D010146:Pain / Q000000981:diagnostic imaging* / Q000209:etiology / Q000503:physiopathology; D011859:Radiography; D016059:Range of Motion, Articular / Q000502:physiology*; D012189:Retrospective Studies