title: [Possibilities for interpreting digital migration analysis of cement-free PM total hip endoprostheses].
abstract: OBJECTIVE
  Aim of this study was the validation of a digital measurement device for hip implants.
  
  
  METHODS
  From 43 patients with a minimum of four subsequent roentgenograms 246 roentgenograms of PM-shafts (an average 5.72/shaft) and 142 roentgenograms of PM-cups (an average 6.45/cup) were digitized on a DiagnostiX 2048 basis station (Pace Systems, Germany). Modified Sutherland/Nunn methods were chosen for measuring purposes. Regression analysis was done and the results were correlated to implant loosening.
  
  
  RESULTS
  Concerning the total vertical migration of the cup there is a significant (p < 0.04) difference between the loosened components (6.02 +/- 2.59 mm) and the fixed cups (2.26 +/- 2.89 mm). The average annual vertical migration rate of the stem shows a highly significant difference (p < 0.007) when comparing loosened stems (0.82 +/- 0.43 mm, total migration 4.78 +/- 2.89 mm) and fixed ones (0.20 +/- 0.54 mm, total migration 1.72 +/- 3.02 mm)
  
  
  CONCLUSIONS
  Using the regression analysis and a sufficient number of pictures the system allows us to give migration values that make loosening likely. However for the single implant an individual prognosis of loosening is not possible.
authors.affiliation: Orthopädische Universitätsklinik Würzburg, König-Ludwig-Haus.
authors.forename: C
authors.initials: C
authors.lastname: Hendrich
authors.forename: C P
authors.initials: CP
authors.lastname: Rader
authors.forename: G
authors.initials: G
authors.lastname: Klein
authors.forename: B
authors.initials: B
authors.lastname: Oswald
authors.forename: C
authors.initials: C
authors.lastname: Kramer
mesh_terms: D005500:Follow-Up Studies; D006622:Hip Prosthesis; D006801:Humans; D008432:Mathematical Computing; D011183:Postoperative Complications / Q000000981:diagnostic imaging*; D011474:Prosthesis Design; D011475:Prosthesis Failure; D011857:Radiographic Image Interpretation, Computer-Assisted; D012307:Risk Factors; D012984:Software