title: A new automated way to measure polyethylene wear in THA using a high resolution CT scanner: method and analysis.
abstract: As the most advantageous total hip arthroplasty (THA) operation is the first, timely replacement of only the liner is socially and economically important because the utilization of THA is increasing as younger and more active patients are receiving implants and they are living longer. Automatic algorithms were developed to infer liner wear by estimating the separation between the acetabular cup and femoral component head given a computed tomography (CT) volume. Two series of CT volumes of a hip phantom were acquired with the femoral component head placed at 14 different positions relative to the acetabular cup. The mean and standard deviation (SD) of the diameter of the acetabular cup and femoral component head, in addition to the range of error in the expected wear values and the repeatability of all the measurements, were calculated. The algorithms resulted in a mean (± SD) for the diameter of the acetabular cup of 54.21 (± 0.011) mm and for the femoral component head of 22.09 (± 0.02) mm. The wear error was ± 0.1 mm and the repeatability was 0.077 mm. This approach is applicable clinically as it utilizes readily available computed tomography imaging systems and requires only five minutes of human interaction.
authors.affiliation: School of Information and Communication Technology, KTH Royal Institute of Technology, Isafjordsgatan 26, 418 164-40 Stockholm, Sweden.
authors.forename: Gerald Q
authors.initials: GQ
authors.lastname: Maguire
authors.affiliation: Department of Radiology, New York University, 550 First Avenue TSHW232, New York, NY 10016, USA.
authors.forename: Marilyn E
authors.initials: ME
authors.lastname: Noz
authors.affiliation: Department of Molecular Medicine and Surgery, Section of Orthopaedics and Sports Medicine, Karolinska Institute, A2:07, 171 76 Stockholm, Sweden.
authors.forename: Henrik
authors.initials: H
authors.lastname: Olivecrona
authors.affiliation: School of Computing, University of Utah, College of Engineering, 50 Central Campus Dr., Room 3190, Salt Lake City, UT 84112, USA.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Zeleznik
authors.affiliation: Department of Molecular Medicine and Surgery, Section of Orthopaedics and Sports Medicine, Karolinska Institute, A2:07, 171 76 Stockholm, Sweden.
authors.forename: Lars
authors.identifier: 0000-0002-4280-1178
authors.initials: L
authors.lastname: Weidenhielm
mesh_terms: D019644:Arthroplasty, Replacement, Hip / Q000379:methods*; D003627:Data Interpretation, Statistical; D006621:Hip Joint / Q000000981:diagnostic imaging*; D006622:Hip Prosthesis; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000379:methods; D008422:Materials Testing / Q000379:methods*; D019047:Phantoms, Imaging; D020959:Polyethylene / Q000737:chemistry* / Q000627:therapeutic use; D011475:Prosthesis Failure; D014057:Tomography, X-Ray Computed / Q000379:methods*
chemical_list: D020959:Polyethylene