title: Measurement of polyethylene wear - a new three-dimensional methodology.
abstract: Studies in the field of polyethylene wear of the acetabular cup have been generally discussed using a two-dimensional assumption on the coronal plane; significant errors thus appear. The present study proposes a new, advanced methodology in order to accurately estimate the polyethylene wear. Through the usage of the distance between X-ray focus and film and only one follow-up, anteroposterior (AP) radiograph, a three-dimensional (3D) algorithm is introduced here. Here, 91 primary total hip joint replacements in 67 patients have been examined and three findings are obtained. Results show that the mean rate of 3D linear wear of the polyethylene estimated by the current method is 0.230+/-0.036 mm per year, that of the 2D linear wear is 0.148+/-0.028 mm per year. Moreover, the wear depth of the femoral head on the sagittal plane is 0.173+/-0.043 mm per year by the current method. This study also shows that the adoption of only one AP radiograph in the evaluation of the 3D penetration of femoral head is possible. Furthermore, the methodology proposed here is more convenient than others.
authors.affiliation: Department of Physical Therapy, Chung Shan Medical and Dental College, Taichung, Taiwan, ROC.
authors.forename: Jian-Horng
authors.initials: JH
authors.lastname: Chen
authors.forename: James
authors.initials: J
authors.lastname: Shih-Shyn Wu
mesh_terms: D000328:Adult; D000465:Algorithms; D001672:Biocompatible Materials; D006621:Hip Joint / Q000000981:diagnostic imaging; D006622:Hip Prosthesis; D006801:Humans; D008422:Materials Testing / Q000706:statistics & numerical data*; D008875:Middle Aged; D020959:Polyethylene; D011475:Prosthesis Failure; D011856:Radiographic Image Enhancement
chemical_list: D001672:Biocompatible Materials; D020959:Polyethylene