title: Cementless Hip Stem Anteversion in the Dysplastic Hip: A Comparison of Tapered Wedge vs Metaphyseal Filling.
abstract: Appropriate stem anteversion is important for achieving stability of the prosthetic joint in total hip arthroplasty. Anteversion of a cementless femoral stem is affected by the femoral canal morphology and varies according to stem geometry. We investigated the difference and variation of the increase in anteversion between 2 types of cementless stems, and the correlation between each stem and the preoperative femoral anteversion.
  
  
  
  We retrospectively compared 2 groups of hips that underwent total hip arthroplasty using a metaphyseal filling stem (78 hips) or a tapered wedge stem (83 hips). All the patients had osteoarthritis due to hip dysplasia. Computed tomography was used to measure preoperative femoral anteversion at 5 levels and postoperative stem anteversion.
  
  
  
  The increase in anteversion of the tapered wedge stem group (22.7° ± 11.6°) was more than that of the metaphyseal filling stem group (17.2° ± 8.3°; P = .0007). The variation of the increase in the tapered wedge stem group was significantly larger than that in the metaphyseal filling stem group (P = .0016). The metaphyseal filling stem group was more highly and positively correlated with femoral anteversion than the tapered wedge stem group.
  
  
  
  Femoral anteversion affects stem anteversion differently according to stem geometry. The tapered wedge stems had greater variation of the increase in anteversion than did the metaphyseal filling stems. Based on the results of this study, it is difficult to preoperatively estimate the increase in stem anteversion for tapered wedge stems.
authors.affiliation: Department of Orthopaedic Surgery, University of Yamanashi, Chuo-shi, Yamanashi, Japan; Department of Orthopaedic Surgery, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
authors.forename: Naofumi
authors.initials: N
authors.lastname: Taniguchi
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Jinno
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Koga
authors.affiliation: Department of Orthopaedic Surgery, Kofu National Hospital, Kofu-shi, Yamanashi, Japan.
authors.forename: Tetsuo
authors.initials: T
authors.lastname: Hagino
authors.affiliation: Department of Orthopaedic Surgery, Tokyo Medical and Dental University, Bunkyo-ku, Tokyo, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Okawa
authors.affiliation: Department of Orthopaedic Surgery, University of Yamanashi, Chuo-shi, Yamanashi, Japan.
authors.forename: Hirotaka
authors.initials: H
authors.lastname: Haro
mesh_terms: D000368:Aged; D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects* / Q000295:instrumentation / Q000379:methods*; D001843:Bone Cements; D017760:Bone Malalignment / Q000209:etiology / Q000517:prevention & control*; D002484:Cementation; D005260:Female; D005269:Femur / Q000000981:diagnostic imaging / Q000601:surgery; D006618:Hip Dislocation, Congenital / Q000150:complications / Q000601:surgery*; D006622:Hip Prosthesis / Q000009:adverse effects; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000209:etiology / Q000601:surgery*; D011474:Prosthesis Design; D012189:Retrospective Studies; D014057:Tomography, X-Ray Computed
chemical_list: D001843:Bone Cements
keywords: Level III; cementless stem; dislocation; femoral canal; impingement; instability; stem geometry; therapeutic study