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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.i1.40
pages 27-34

Technique to Quantify Subsurface Cracks in Retrieved Polyethylene Components Using Micro-CT

Matthew G Teeter
Division of Orthopaedic Surgery, London Health Sciences Centre, London, Ontario, N6A 5A5, Canada
Xunhua Yuan
Imaging Research Laboratories, Robarts Research Institute; Department of Medical Biophysics, The University of Western 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

No current method to study delamination and subsurface cracking in polyethylene joint replacement components provides accurate, nondestructive, and quantitative measurements. A technique to study damage both at and below the surface could be of great benefit. We report the development of a micro-CT technique to nondestructively examine and quantify subsurface cracking in retrieved polyethylene tibial inserts. Five severely delaminated inserts and two never-implanted inserts were obtained from our institution's implant retrieval library and scanned with micro-CT. The insert subsurface was examined for cracks, and their location and widths were measured using a digital line tool. Subsurface cracks were readily apparent only in the images of the delaminated inserts. Cracks ran horizontally, just below the articular and back-side surfaces, and vertically at the center and lateral edges of the inserts and at the tibial post. Cracks ranged from 0.12 to 6.01 mm below the surface, with widths of 0.06-0.97 mm. Micro-CT can nondestructively visualize and quantify subsurface cracks. This is an enhancement to its previously reported use to quantify surface deviations from wear. Micro-CT is well suited for longitudinal pin-on-disk and wear simulator trials, in addition to studies of retrieved components.