Time filter

Source Type

Brandt J.-M.,Concordia Joint Replacement Group | Gascoyne T.C.,Concordia Joint Replacement Group | Guenther L.E.,Concordia Joint Replacement Group | Allen A.,Dalhousie University | And 4 more authors.
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine | Year: 2013

The present study investigates the performance of ceramic-on-ceramic total hip replacements by combining a retrieval analysis with a survivorship analysis to elucidate mechanisms that led to clinical failure. Semiquantitative surface damage assessment, contact profilometry, contour measurements, and scanning electron microscopy were performed to characterize the types and quantify the extent of surface damage on the retrieved ceramic components. The implantation period was positively correlated with both damage scores of the femoral heads (R = 0.573, p < 0.001) and the acetabular cups (R = 0.592, p < 0.001). Increased maximal out-of-roundness values of the femoral heads correlated with both increased metal transfer damage score (R = 0.384, p = 0.023) and increased stripe damage score (R = 0.729, p≤ 0.001) of the acetabular liners. The damage rate (damage score/year) for both the retrieved heads and acetabular liners was at least 2.2-fold greater at inclination angles of >45° than the damage rate at inclination angles of ≤45°. For the retrieved femoral heads only, the linear wear rate of 25.5 ± 21.3 μm/year at inclination angles of >45° was 6-fold greater than the linear wear rate of 4.2 ± 2.3 μm/year at inclination angles of ≤45°. Metal transfer on the ceramic bearing surface could possibly contribute to fluid-film starvation and, in combination with an increased inclination angle, may facilitate an adhesive wear mechanism associated with stripe surface damage. At our institution, the clinical survivorship of ceramicon-ceramic total hip replacements was 98.9% (a total of 9 out of 815 patients were revised within 10 years after total hip arthroplasty) with revision as the end point, suggesting their safe use in younger patients. © IMechE 2013.

O'Brien S.,University of Manitoba | O'Brien S.,Concordia Hip and Knee Institute | Luo Y.,University of Manitoba | Wu C.,University of Manitoba | And 5 more authors.
Tribology International | Year: 2013

A computational model to predict polyethylene wear in modular total knee replacements was developed. The results from knee simulator wear tests were implemented with finite element simulations to identify the wear factors of Archard's wear law. The calculated wear factor for the articular and backside surface was 1.03±0.22×10-7 mm3/Nm and 2.43±0.52×10-10 mm3/Nm, respectively. The difference in wear factors was attributed to differences in wear mode and wear mechanisms between the articular (mainly two-body rolling/sliding wear mode with an abrasive/adhesive wear mechanism) and the backside surfaces (mainly fretting wear mode with an adhesive wear mechanism). © 2012 Elsevier Ltd.

Brandt J.-M.,Concordia Joint Replacement Group | Guenther L.,Concordia Joint Replacement Group | O'Brien S.,Concordia Joint Replacement Group | Vecherya A.,Concordia Joint Replacement Group | And 3 more authors.
Knee | Year: 2013

Background: The surface characteristics of the femoral component affect polyethylene wear in modular total knee replacements. In the present retrieval study, the surface characteristics of cobalt-chromium (CoCr) alloy and oxidized zirconium (OxZr) femoral components were assessed and compared. Methods: Twenty-six retrieved CoCr alloy femoral components were matched with twenty-six retrieved OxZr femoral components for implantation period, body-mass index, patient gender, implant type, and polyethylene insert thickness. The surface damage on the retrieved femoral components was evaluated using a semi-quantitative assessment method, scanning electron microscopy, and contact profilometry. Results: The retrieved CoCr alloy femoral components showed less posterior surface gouging than OxZr femoral components; however, at a higher magnification, the grooving damage features on the retrieved CoCr alloy femoral components confirmed an abrasive wear mechanism. The surface roughness values Rp, Rpm, and Rpk for the retrieved CoCr alloy femoral components were found to be significantly higher than those of the retrieved OxZr femoral components (p ≤ 0.031). The surface roughness values were higher on the medial condyles than on the lateral condyles of the retrieved CoCr alloy femoral components; such a difference was not observed on the retrieved OxZr femoral components. Conclusions: The surface roughness of CoCr alloy femoral components increased while the surface roughness of the OxZr femoral components remained unchanged after in vivo service. Therefore, the OxZr femoral components' resistance to abrasive wear may enable lower polyethylene wear and ensure long-term durability in vivo. Level of Evidence: Level IV. © 2013.

ORTHOPAEDIC INNOVATION Center INC. | Date: 2013-11-14

An antibiotic-eluting article for implantation into a mammalian subject, produced by an additive manufacturing process wherein a polymeric material is concurrently deposited with a selected antibiotic. The additive manufacturing process may be a fused deposition modeling process, a selective laser sintering process, a selective heat sintering process, a digital light processing process, or a stereolithography process. The antibiotic-eluting article may be temporary or permanent orthopaedic skeletal component, an orthopaedic articulating joint replacement component, and/or an external hard-shell casing for an implantable device. One or more bone-growth-promoting compositions may be concurrently deposited with the polymeric material. The implantable device may be a cardiac pacemaker, a spinal cord stimulator, a neurostimulation system, an intrathecal drug pump for delivery of medicants into the spinal fluid, and infusion pump for delivery of chemotherapeutics and/or anti-spasmodics, an insulin pump, an osmotic pump, and a heparin pump.

Orthopaedic Innovation Center Inc. | Date: 2015-11-24

Knee implants. Custom implant and orthopaedic sizing services.

Discover hidden collaborations