title: The direct lateral approach: impact on gait patterns, foot  progression angle and pain in comparison with a minimally  invasive anterolateral approach.
abstract: BACKGROUND
  Minimally invasive total hip arthroplasty has been successfully introduced in the past decade. Nevertheless, standard approaches such as the direct lateral approach are still commonly used in orthopaedic surgery due to easy handling, good intra-operative overview and low complication rates. However, a frequent occurrence of fatty atrophy within the anterior third of the gluteus medius muscle has been demonstrated when using the modified direct-lateral approach (mDL), which may be associated with a reduction in function, limitation of internal leg rotation, gait disorders and pain. The question addressed in this study is whether mDL-approach leads to unfavourable changes in foot progression angle (FPA), gait and to more postoperative pain compared with a minimally invasive anterolateral approach (ALMI).
  
  
  METHODS
  Thirty patients with primary osteoarthritis of the hip were recruited for this study. All subjects received an uncemented THA (Alloclassic-Zweymüller stem, Allofit Cup, FA Zimmer), 15 through an ALMI-approach and 15 via the mDL-approach. Gait analyses were performed both preoperatively and 3 months after surgery to measure FPA, step length, stance duration, cadence and walking speed. Additionally, the Harris-Hip Score, pain according to the visual analogue scale and the Trendelenburg sign were evaluated.
  
  
  RESULTS
  No influence of the surgical approach could be observed on the gait patterns or FPA. Furthermore, neither increased external rotation of the limb nor restriction of internal rotation during walking could be established. Pain and Harris-Hip Score did not diVer significantly between the two groups.
  
  
  CONCLUSIONS
  In comparison with an ALMI approach, the mDL approach did not lead to a change in FPA postoperatively. No detrimental effect could be found on the gait pattern or pain after surgery. Based on these measurements, the minimally invasive anterolateral approach did not appear to provide functional benefits in outcome over the mDL approach. Consequently, both surgical approaches seem to be equally applicable approaches with good to very good functional results.
authors.affiliation: Department of Orthopedics, Center for Musculoskeletal Surgery, Charité-Universitätsmedizin Berlin, Berlin, Germany. michael.mueller@charite.de
authors.forename: Michael
authors.initials: M
authors.lastname: Müller
authors.forename: Verena
authors.initials: V
authors.lastname: Schwachmeyer
authors.forename: Stephan
authors.initials: S
authors.lastname: Tohtz
authors.forename: William R
authors.initials: WR
authors.lastname: Taylor
authors.forename: Georg N
authors.initials: GN
authors.lastname: Duda
authors.forename: Carsten
authors.initials: C
authors.lastname: Perka
authors.forename: Markus O
authors.initials: MO
authors.lastname: Heller
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D001696:Biomechanical Phenomena; D005260:Female; D005684:Gait; D006621:Hip Joint / Q000503:physiopathology; D006801:Humans; D008297:Male; D008875:Middle Aged; D019060:Minimally Invasive Surgical Procedures; D015207:Osteoarthritis, Hip / Q000601:surgery; D010149:Postoperative Pain; D016059:Range of Motion, Articular; D016138:Walking