title: Early subsidence of shape-closed hip arthroplasty stems is associated with late revision. A systematic review and meta-analysis of 24 RSA studies and 56 survival studies.
abstract: OBJECTIVE
  Few studies have addressed the association between early migration of femoral stems and late aseptic revision in total hip arthroplasty. We performed a meta-regression analysis on 2 parallel systematic reviews and meta-analyses to determine the association between early migration and late aseptic revision of femoral stems.
  
  
  METHODS
  Of the 2 reviews, one covered early migration data obtained from radiostereometric analysis (RSA) studies and the other covered long-term aseptic revision rates obtained from survival studies with endpoint revision for aseptic loosening. Stems were stratified according to the design concept: cemented shape-closed, cemented force-closed, and uncemented. A weighted regression model was used to assess the association between early migration and late aseptic revision, and to correct for confounders. Thresholds for acceptable and unacceptable migration were determined in accordance with the national joint registries (≤ 5% revision at 10 years) and the NICE criteria (≤ 10% revision at 10 years).
  
  
  RESULTS
  24 studies (731 stems) were included in the RSA review and 56 studies (20,599 stems) were included in the survival analysis review. Combining both reviews for the 3 design concepts showed that for every 0.1-mm increase in 2-year subsidence, as measured with RSA, there was a 4% increase in revision rate for the shape-closed stem designs. This association remained after correction for age, sex, diagnosis, hospital type, continent, and study quality. The threshold for acceptable migration of shape-closed designs was defined at 0.15 mm; stems subsiding less than 0.15 mm in 2 years had revision rates of less than 5% at 10 years, while stems exceeding 0.15 mm subsidence had revision rates of more than 5%.
  
  
  CONCLUSIONS
  There was a clinically relevant association between early subsidence of shape-closed femoral stems and late revision for aseptic loosening. This association can be used to assess the safety of shape-closed stem designs. The published research is not sufficient to allow us to make any conclusions regarding such an association for the force-closed and uncemented stems.
authors.affiliation: a 1 Department of Orthopaedics, Biomechanics and Imaging Group , Leiden University Medical Center, Leiden.
authors.forename: Paul
authors.initials: P
authors.lastname: van der Voort
authors.affiliation: a 1 Department of Orthopaedics, Biomechanics and Imaging Group , Leiden University Medical Center, Leiden.
authors.forename: Bart G
authors.initials: BG
authors.lastname: Pijls
authors.affiliation: a 1 Department of Orthopaedics, Biomechanics and Imaging Group , Leiden University Medical Center, Leiden.
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Nieuwenhuijse
authors.affiliation: a 1 Department of Orthopaedics, Biomechanics and Imaging Group , Leiden University Medical Center, Leiden.
authors.forename: Jorrit
authors.initials: J
authors.lastname: Jasper
authors.affiliation: d 4 Department of Medical Statistics and Bioinformatics , Leiden University Medical Center, Leiden.
authors.forename: Marta
authors.initials: M
authors.lastname: Fiocco
authors.affiliation: c 3 Walaeus Library.
authors.forename: Josepha W M
authors.initials: JW
authors.lastname: Plevier
authors.affiliation: e 5 Academic Medical Center, Department of Vascular Medicine , Amsterdam.|f 6 Department of Clinical Epidemiology , Leiden University Medical Center, Leiden, the Netherlands.
authors.forename: Saskia
authors.initials: S
authors.lastname: Middeldorp
authors.affiliation: a 1 Department of Orthopaedics, Biomechanics and Imaging Group , Leiden University Medical Center, Leiden.|b 2 Department of Biomechanical Engineering, Faculty of Mechanical, Maritime and Materials Engineering , University of Technology, Delft.
authors.forename: Edward R
authors.initials: ER
authors.lastname: Valstar
authors.affiliation: a 1 Department of Orthopaedics, Biomechanics and Imaging Group , Leiden University Medical Center, Leiden.
authors.forename: Rob G H H
authors.initials: RG
authors.lastname: Nelissen
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000009:adverse effects*; D006622:Hip Prosthesis / Q000009:adverse effects*; D006801:Humans; D011474:Prosthesis Design / Q000009:adverse effects*; D011475:Prosthesis Failure; D059869:Radiostereometric Analysis; D012086:Reoperation / Q000379:methods; D012307:Risk Factors; D016896:Treatment Outcome