Library Subscription: Guest
Begell Digital Portal Begell Digital Library eBooks Journals References & Proceedings Research Collections
Journal of Long-Term Effects of Medical Implants

ISSN Print: 1050-6934
ISSN Online: 1940-4379

Journal of Long-Term Effects of Medical Implants

DOI: 10.1615/JLongTermEffMedImplants.v20.i1.70
pages 49-56

Regional Measurements of Surface Deviation Volume in Worn Polyethylene Joint Replacement Components

Matthew G Teeter
Division of Orthopaedic Surgery, London Health Sciences Centre, London, Ontario, N6A 5A5, Canada
Jaques S. Milner
Imaging Research Laboratories, Robarts Research Institute, London, Ontario
Jennifer L. Au
Imaging Research Laboratories, Robarts Research Institute, London, Ontario
Daniel Lorusso
Imaging Research Laboratories, Robarts Research Institute, London, Ontario
Douglas D. R. Naudie
Division of Orthopaedic Surgery, The University of Western Ontario, London, ON
David W. Holdsworth
Imaging Research Laboratories, Robarts Research Institute; Department of Medical Biophysics; Division of Orthopaedic Surgery, The University of Western Ontario

ABSTRACT

Total joint replacements can be subject to the loss of polyethylene material due to wear, leading to osteolysis and decreased implant longevity. Micro-computed tomography (micro-CT) techniques have recently been developed to calculate 3D surface deviations in worn implant components. We describe a micro-CT technique to measure the volume of the surface deviations (volume of wear plus creep) within a specific region or compartment, and report its repeatability and reproducibility. Six worn polyethylene tibial inserts were scanned using a laboratory micro-CT scanner and subsequently reconstructed at 50 μm voxel spacing. A previously developed custom software application was used to quantify the 3D surface deviations between the worn tibial inserts and an unworn reference geometry. Three observers (two trained and one expert) used new custom software to manually outline the localized regions of surface deviation (three times for each of the worn inserts) and calculate the volume of the deviations. The overall intrao- bserver variability in the surface deviation volumes was 3.6% medially and 1.1% laterally. The overall in- terobserver variability was 4.8% medially and 1.7% laterally. Placement of points in outlining the region of deviation contributed the greatest variability to the measurements. Repeatability and reproducibility of the volume measurements are similar to measurements of total (nonregional) wear volume including a previous micro-CT technique (10%), fluid displacement (4.8%), and radiographic measurements (15.7%). The principles of this technique can likely be used to measure regional wear and creep volume in knee and hip joint replacement components from wear simulator, pin-on-disk, and retrieval studies.