title: The etiology of femoroacetabular impingement: what we know and what we don't.
abstract: BACKGROUND
  Several risk factors may cause femoroacetabular impingement (FAI). Knowledge of causation would identify patients for early intervention, prior to the development of painful intra-articular damage.
  
  
  METHODS
  PubMed, MEDLINE, EMBASE, and related article reference lists were screened for relevant studies published between January 2000 and December 2013.
  
  
  METHODS
  Inclusion criteria were (1) etiology of FAI, (2) original FAI clinical data, and (3) English language. Case reports of fewer than 3 patients were excluded.
  
  
  METHODS
  Systematic review.
  
  
  METHODS
  Level 4.
  
  
  RESULTS
  In all, 754 studies were screened, with 18 meeting the eligibility criteria. There were 13 comparative observational studies and 5 case series. The studies pertained to intrinsic patient factors (n = 2), activity/developmental factors (n = 8), hip disease (n = 5), postsurgical changes (n = 2), and malunion after hip fracture (n = 1).
  
  
  CONCLUSIONS
  A combination of intrinsic patient and developmental factors, activities involving repetitive hip motion, pediatric hip disease, and hip-related surgical procedures may contribute to the development of FAI.
authors.affiliation: Division of Orthopaedic Surgery, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Harman
authors.initials: H
authors.lastname: Chaudhry
authors.affiliation: Division of Orthopaedic Surgery, McMaster University, Hamilton, Ontario, Canada.
authors.forename: Olufemi R
authors.initials: OR
authors.lastname: Ayeni
keywords: etiology; femoroacetabular impingement; hip; systematic review