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A computerized analysis‐by‐synthesis algorithm improves precision of linear wear measurements in total hip replacements
Author(s) -
Dora Claudio,
Burckhardt Kathrin,
Székely Gábor,
Rousson Valentin,
Hodler Juerg,
Gerber Christian
Publication year - 2008
Publication title -
journal of orthopaedic research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.041
H-Index - 155
eISSN - 1554-527X
pISSN - 0736-0266
DOI - 10.1002/jor.20643
Subject(s) - wilcoxon signed rank test , cad , algorithm , accuracy and precision , total hip replacement , implant , computer science , biomedical engineering , mathematics , statistics , engineering drawing , medicine , engineering , surgery , mann–whitney u test
Precision is important if small polyethylene wear rates are to be detected early and in small sample sizes. Using an automatic, computerized algorithm relying on a synthetic X‐ray generated from a computer‐assisted design (CAD) model of the implant may significantly improve precision of linear wear measurements. We compared this method to provide improved in vivo precision compared to the widely used Hip Analysis Suite™ software (version 8.0.1.7). Two anterior–posterior pelvic X‐rays were taken on the same day of 18 total hip implants, and wear was measured by three observers using the two methods. Expected real wear was zero and defined as a reference value. Two sources of variability were estimated: one due to the instrument, and one due to different operators. A Wilcoxon Signed Rank Test was used for statistical comparisons. The overall precision (instrument variability and multioperator variability) given a 95% precision limit was significantly higher ( p < 0.001) using the proposed method (±0.15 mm) when compared to the Hip Analysis Suite (±0.84 mm). Due to the availability of the full CAD data of the implant and to further automation of the measuring process, the newly proposed method provided improved precision in measuring polyethylene wear. © 2008 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 26:1121–1126, 2008