Work

Sliding Direction Dependence of Polyethylene Wear for Metal Counterface Traverse of Severe Scratches

Year: 2008

Type: article

Abstract: Third-body effects appear to be responsible for an appreciable portion of the wear rate variability within cohorts of patients with metal-on-polyethylene joint replacements. The parameters dominating the rate of polyethylene debris liberation by counterface scratches are not fully understood, but one seemingly contributory factor is the scratch's orientation relative to the direction of instantaneous local surface sliding. To study this influence, arrays of 550 straight parallel scratches each representative of the severe end of the clinical range were diamond stylus-ruled onto the surface of polished stainless steel plates. These ruled plates were then worn reciprocally against polyethylene pins (both conventional and highly cross-linked) at traverse angles varied parametrically relative to the scratch direction. Wear was measured gravimetrically, and particulate debris was harvested and morphologically characterized. Both of the polyethylene variants tested showed pronounced wear rate peaks at acute scratch traverse angles (15 deg for conventional and 5 deg for cross-linked), and had nominally comparable absolute wear rate magnitudes. The particulate debris from this very aggressive test regime primarily consisted of extremely large and elongated strands, often tens or even hundreds of microns in length. These data suggest that counterface damage regions with preferential scratch directionality can liberate large amounts of polyethylene debris, apparently by a slicing/shearing mechanism, at critical (acute) attack angles. However, the predominant manifestation of this wear volume was in the form of particles far beyond the most osteolytically potent size range.

Source: Journal of Biomechanical Engineering

DOI: 10.1115/1.2947157

Authors: Liam P. Glennon, Thomas E. Baer, James A. Martin, William D. Lack, Thomas D. Brown

Institution: University of Iowa

Language: English

Topic: Orthopaedic implants and arthroplasty

Subfield: Surgery

Field: Medicine

Domain: Health Sciences

Open Access status: green

Funders: Hospital for Special Surgery, National Institutes of Health, National Institute of Arthritis and Musculoskeletal and Skin Diseases

Awards: G1287966776, Mechanisms of Third Body Acceleration of THA Wear, NONLINEAR COMPUTATIONAL BIOMECHANICS OF THE HIP, G878232636, NONLINEAR COMPUTATIONAL BIOMECHANICS OF THE HIP