title: Does stem design influence component positioning in total hip arthroplasty using a minimal invasive posterolateral approach?
abstract: OBJECTIVE
  Limited data exist for the reconstructive potential of short bone-preserving stems in THA using a minimal invasive posterolateral approach. Our study aim was to assess the effect of stem design on the reconstruction of hip offset and leg length in MIS posterolateral THA.
  
  
  METHODS
  This retrospective consecutive single-surgeon study compares hip offset and leg length, as well as acetabular component positioning (cup anteversion; inclination) of 129 THAs with a cementless standard-length stem (Synergy®) and 143 THAs with a cementless short bone-preserving stem (Trilock®).
  
  
  RESULTS
  In reference to the contralateral side, the mean difference in hip offset was 0.9 mm (p = 0.067) for the standard stem and 0.1 mm (p = 0.793) for the short stem, respectively. Leg-length discrepancy was 0.7 mm (Synergy®) and 0.9 mm (Trilock®), respectively. A total of 233 (86 %) acetabular components fell within the target zone for anteversion and inclination.
  
  
  CONCLUSIONS
  Accurate component positioning in MIS posterolateral approach THA is possible and is not influenced by the type of stem.
authors.affiliation: Orthopaedic Surgery, Hospital for Special Surgery, New York, NY, USA.
authors.forename: Wenzel
authors.initials: W
authors.lastname: Waldstein
authors.forename: Christian
authors.initials: C
authors.lastname: Merle
authors.forename: Tom
authors.initials: T
authors.lastname: Schmidt-Braekling
authors.forename: Friedrich
authors.initials: F
authors.lastname: Boettner
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip; D005260:Female; D006621:Hip Joint / Q000601:surgery*; D006622:Hip Prosthesis; D006801:Humans; D007592:Joint Diseases / Q000601:surgery*; D007870:Leg Length Inequality / Q000601:surgery; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D011474:Prosthesis Design; D012189:Retrospective Studies; D055815:Young Adult