title: Influence of surgical approach on component positioning in primary total hip arthroplasty.
abstract: BACKGROUND
  Minimal invasive surgery (MIS) has gained growing popularity in total hip arthroplasty (THA) but concerns exist regarding component malpositioning. The aim of the present study was to evaluate femoral and acetabular component positioning in primary cementless THA comparing a lateral to a MIS anterolateral approach.
  
  
  METHODS
  We evaluated 6 week postoperative radiographs of 52 hips with a minimal invasive anterolateral approach compared to 54 hips with a standard lateral approach. All hips had received the same type of implant for primary cementless unilateral THA and had a healthy hip contralaterally.
  
  
  RESULTS
  Hip offset was equally restored comparing both approaches. No influence of the approach was observed with regard to reconstruction of acetabular offset, femoral offset, vertical placement of the center of rotation, stem alignment and leg length discrepancy. However, with the MIS approach, a significantly higher percentage of cups (38.5 %) was malpositioned compared to the standard approach (16.7 %) (p = 0.022).
  
  
  CONCLUSIONS
  The MIS anterolateral approach allows for comparable reconstruction of stem position, offset and center of rotation compared to the lateral approach. However, surgeons must be aware of a higher risk of cup malpositioning for inclination and anteversion using the MIS anterolateral approach.
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Heidelberg, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany. Moritz.Innmann@med.uni-heidelberg.de.
authors.forename: Moritz M
authors.initials: MM
authors.lastname: Innmann
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Heidelberg, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany. marcus.streit@arcor.de.
authors.forename: Marcus R
authors.initials: MR
authors.lastname: Streit
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Heidelberg, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany. jeannette.kolb@web.de.
authors.forename: Jeanette
authors.initials: J
authors.lastname: Kolb
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Heidelberg, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany. jochenheiland@gmx.de.
authors.forename: Jochen
authors.initials: J
authors.lastname: Heiland
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Karl-Olga-Krankenhaus, Hackstraße 61, 70190, Stuttgart, Germany. Dominik.Parsch@sana.de.
authors.forename: Dominik
authors.initials: D
authors.lastname: Parsch
authors.affiliation: Department of Orthopaedic and Trauma Surgery, Paulinenhilfe, Diakonieklinikum, Rosenbergstrasse 38, 70192, Stuttgart, Germany. Peter.Aldinger@diak-stuttgart.de.
authors.forename: Peter R
authors.initials: PR
authors.lastname: Aldinger
authors.affiliation: Chirurgische Universitätsklinik und Poliklinik, Berufsgenossenschaftliches Universitätsklinikum Bergmannsheil, Bürkle-de-la-Camp-Platz 1, 44789, Bochum, Germany. Matthias.Koenigshausen@bergmannsheil.de.
authors.forename: Matthias
authors.initials: M
authors.lastname: Königshausen
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Heidelberg, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany. Tobias.Gotterbarm@med.uni-heidelberg.de.
authors.forename: Tobias
authors.initials: T
authors.lastname: Gotterbarm
authors.affiliation: Department of Orthopaedic and Trauma Surgery, University of Heidelberg, Schlierbacher Landstrasse 200a, 69118, Heidelberg, Germany. Christian.Merle@med.uni-heidelberg.de.
authors.forename: Christian
authors.initials: C
authors.lastname: Merle
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D015331:Cohort Studies; D005260:Female; D006621:Hip Joint / Q000000981:diagnostic imaging* / Q000601:surgery*; D006801:Humans; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures / Q000379:methods*; D056888:Patient Positioning / Q000379:methods*; D011859:Radiography; D012189:Retrospective Studies; D055815:Young Adult