title: Preoperative Planning and Operative Techniques of the Shorter Tapered Stem Compared to the Metaphyseal Fit Stem in Cementless Total Hip Arthroplasty.
abstract: In order to prevent postoperative dislocation due to prosthetic impingement as a result of total hip arthroplasty (THA), the combined anteversion (CA) theory, which combines the anteversion of the femoral stem and the acetabular socket, has been revised in recent years. Particularly, it is necessary to keep CA within the target zone.
  
  
  
  The aim of this study was to investigate whether postoperative CA can be kept within the target zone while using the operative technique which prepares the socket first in cementless THA, by estimating the anteversion of the metaphyseal fit stem or the shorter, tapered wedge stem using preoperative 3-dimensional computerized planning, and by adjusting the anteversion of the socket using a navigation system that considers CA. One hundred fourteen patients (118 hips) were recruited for the study.
  
  
  
  Postoperative CA in THA using the metaphyseal fit stem was kept within the target zone for 56 of the 60 hips (93.3%). Using the shorter, tapered wedge stem, 49 of the 58 hips (84.4%) were within the target zone. No postoperative dislocations were observed in any hips.
  
  
  
  We found that the metaphyseal fit stem worked better than the shorter, tapered wedge stem in terms of meeting the planned CA. The shorter, tapered wedge stems were flexible in rotation according to the anatomical configuration of the proximal femur. Therefore, the stem could be placed second with the metaphyseal fit stem, but we recommend placing the stem first with the shorter, tapered wedge stem.
authors.affiliation: Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Imai
authors.affiliation: Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.
authors.forename: Joji
authors.initials: J
authors.lastname: Miyawaki
authors.affiliation: Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Kamada
authors.affiliation: Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Maruishi
authors.affiliation: Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Takeba
authors.affiliation: Department of Bone and Joint Surgery, Ehime University Graduate School of Medicine, Toon, Ehime, Japan.
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Miura
mesh_terms: D000077:Acetabulum / Q000601:surgery; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000295:instrumentation / Q000379:methods*; D005260:Female; D005269:Femur / Q000601:surgery; D006621:Hip Joint / Q000601:surgery; D006622:Hip Prosthesis; D006801:Humans; D021621:Imaging, Three-Dimensional; D008297:Male; D008875:Middle Aged; D011184:Postoperative Period; D055815:Young Adult
keywords: cementless total hip arthroplasty; combined anteversion; metaphyseal fit stem; operative technique which prepared stem first; shorter tapered wedge stem