title: The Cementless Spotorno stem in THA: 10 year results.
abstract: BACKGROUND
  The clinical results of total hip arthroplasty (THA) with a cementless prosthesis have been constantly improving due to progress in the area of stem design and surface finish. Cementless Spotorno stem (CLS stem; Zimmer, Warsaw, USA) is a double-tapered rectangular straight stem. The purpose of this study is to investigate the mean 10 year results of CLS stem and to evaluate the press-fit stability of CLS stem.
  
  
  METHODS
  One hundred and eighty-six consecutive patients (194 hips) were evaluated at more than five years after THA using CLS stems. The mean follow-up period was 111 months. The radiographic stability of the femoral stem was determined by Engh's criteria. The ascertained period of spot welds was noted by Gruen zones on the femoral side. The presence of stress shielding, and subsidence was also evaluated.
  
  
  RESULTS
  A stable stem with bony on growth was identified in all cases. The mean period of expression of spot welds was 10.8 months in zone 2, 9.9 months in zone 3, 8.5 months in zone 5, and 8.8 months in zone 6. Stress shielding of more than grade 2 was observed in only three hips, which was non-progressive at one year after surgery. Subsidence of more than 2 mm was not observed in any of the hips.
  
  
  CONCLUSIONS
  Excellent stability of CLS stem has been maintained without abnormal bone reaction at the proximal femur. CLS stem is considered to achieve not only press-fit stability at trochanteric and subtrochanteric level, but bony fixation by osseointegration within one year after THA.
authors.affiliation: 1 Department of Orthopaedic Surgery, Graduate School of Biomedical Sciences, Hiroshima University, Hiroshima - Japan.
authors.forename: Takuma
authors.initials: T
authors.lastname: Yamasaki
authors.forename: Yuji
authors.initials: Y
authors.lastname: Yasunaga
authors.forename: Ryo
authors.initials: R
authors.lastname: Mori
authors.forename: Michio
authors.initials: M
authors.lastname: Hamanishi
authors.forename: Takeshi
authors.initials: T
authors.lastname: Shoji
authors.forename: Mitsuo
authors.initials: M
authors.lastname: Ochi
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D005260:Female; D005500:Follow-Up Studies; D005544:Forecasting; D006622:Hip Prosthesis; D006801:Humans; D008297:Male; D008875:Middle Aged; D015207:Osteoarthritis, Hip / Q000601:surgery*; D011474:Prosthesis Design; D012189:Retrospective Studies; D016896:Treatment Outcome