Aims The purpose of this study was to determine the sensitivity, specificity and predictive values of previously reported thresholds of proximal translation and sagittal rotation of cementless acetabular components used for revision total hip arthroplasty (THA) at various times during early follow-up.
Patients and Methods Migration of cementless acetabular components was measured retrospectively in 84 patients (94 components) using Ein-Bild-Rontgen-Analyse (EBRA-Cup) in two groups of patients. In Group A, components were recorded as not being loose intra-operatively at re-revision THA (52 components/48 patients) and Group B components were recorded to be loose at re-revision (42 components/36 patients).
Results The mean proximal translation and sagittal rotation were significantly higher in Group B than in Group A from three months onwards (p < 0.02). Proximal translation > 1.0 mm within 24 months had a positive predictive value (PPV) of 90% and a specificity of 94%, but a sensitivity of 64%. Proximal translation > 1.0 mm within the first 24 months correctly identified 76 of 94 (81%) of components to be either loose or not loose. However, ten components in Group B (24%) did not migrate proximally above 1.0 mm within the first 60 months.
Conclusion The high PPV of EBRA-Cup measurements of proximal translation (90%) shows that this can be used in early follow-up to identify patients at risk of aseptic loosening. The absence of proximal translation within the first 60 months indicates a component is not likely to be loose at re-revision THA although it does not exclude late aseptic loosening as a cause of failure.
Cite this article: Bone Joint J 2017;99-B:465–74.
- Revision total hip arthroplasty
- Acetabular component migration
- Aseptic loosening
Y. S. Kim: Data collection, Analysis of results, Edited manuscript to publication.
J. M. Abrahams: Ethics submission, Study design, Analysis of results, Wrote initial draft.
S. A. Callary: Planned the study, Analysis of results, Edited manuscript through to publication.
C. De Ieso: Data collection, Analysis of results, Critical review of manuscript.
K. Costi: Assisted with data collection, Critical review of manuscript.
D. W. Howie: Planned the study, Interpretation of results, Critical review of manuscript.
L. B. Solomon: Planned the study, Ethics submission, Interpretation of results, Edited manuscript through to publication.
The authors wish to thank V. Kamalesh (Principal Statistician and Head, Health Statistics Unit, Epidemiology, SA Department for Health and Ageing) for his invaluable statistical support for this project.
The authors also wish to acknowledge the non-commercial project grant funding received from the Royal Adelaide Hospital Research Fund (Callary et al, 2014; $AU40,000).
No benefits in any form have been received or will be received from a commercial party related directly or indirectly to the subject of this article.
This article was primary edited by A. C. Ross.
Supplementary material. A table showing the type of acetabular component used in the index revision for all cases in each group and a figure showing proximal translation over time for ten cases in Group B can be found alongside the online version of this article at www.bjj.boneandjoint.org.uk
- Received August 11, 2016.
- Accepted December 8, 2016.
- ©2017 The British Editorial Society of Bone & Joint Surgery