Archives of Orthopaedic and Trauma Surgery

, Volume 125, Issue 5, pp 291–297

Inter- and intraobserver assessment of periacetabular osteodensitometry after cemented and uncemented total hip arthroplasty using computed tomography


    • Department of OrthopaedicsUniversity of Erlangen-Nuernberg
  • Rocco Paolo Pitto
    • Department of Orthopaedic SurgeryUniversity of Auckland, Middlemore Hospital
  • Alexander Kress
    • Department of OrthopaedicsUniversity of Erlangen-Nuernberg
  • Cornelia Ehremann
    • Department of OrthopaedicsUniversity of Erlangen-Nuernberg
  • Tobias Eckhard Nowak
    • Department of OrthopaedicsUniversity of Erlangen-Nuernberg
  • Udo Reulbach
    • Institut für Medizininformatik, Biometrie und EpidemiologieUniversity of Erlangen-Nuernberg
  • Raimund Forst
    • Department of OrthopaedicsUniversity of Erlangen-Nuernberg
  • Lutz Müller
    • Department of OrthopaedicsUniversity of Erlangen-Nuernberg
Original Article

DOI: 10.1007/s00402-005-0812-8

Cite this article as:
Schmidt, R., Pitto, R.P., Kress, A. et al. Arch Orthop Trauma Surg (2005) 125: 291. doi:10.1007/s00402-005-0812-8



This study was initiated to evaluate the reproducibility of a novel method for measuring the periacetabular bone density after insertion of cemented and uncemented acetabular cups using CT in vivo.

Materials and methods

CT scans were obtained from 20 patients after cemented polyethylene cup implantation (ZCA, Zimmer, USA) and 20 patients after uncemented titanium alloy cup fixation (Cerafit, Ceraver, France). A manual segmentation of cancellous and cortical pelvic bone ventral, dorsal and cranial to the cup was undertaken. Values are given in Hounsfield units. Inter- and intraobserver studies were conducted using a special analysis software tool. To define the reproducibility of the method, all measurements were evaluated according to Bland and Altman.


For both cemented and uncemented acetabular cups, reproducibility of bone density measurement for cortical and cancellous bone cranial, ventral and dorsal to the cup was high. There was no significant difference between the intraobsever study (two repeated measurements) and the interobserver study (two investigators), indicating the reproducibility of the method independent of the investigator.


In conclusion, the periacetabular bone density measurement as conducted in this CT study is a new reproducible method for in vivo evaluation of cortical and cancellous pelvic bone after cemented and uncemented acetabular cup implantation. In vivo CT measurements will allow a thorough assessment of periacetabular stress-shielding phenomena.


ReproducibilityOsteodensitometryBone densityTotal hip arthroplastyComputed tomography

Copyright information

© Springer-Verlag 2005