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Brandt J.-M.,Concordia Joint Replacement Group | Mahmoud K.K.,University of Western Ontario | Mahmoud K.K.,City University of New York | Koval S.F.,University of Western Ontario | And 2 more authors.
Tribology International | Year: 2013

A series of eight wear tests with six different calf serum lubricants were performed on a displacement-controlled knee simulator. The calf serum lubricants varied in constituent fractions, dilutive media, and antimicrobial agent. The difference in low-molecular weight polypeptide concentration was determined in all calf serum lubricants and this allowed exploration of its role in the PE wear process. Sodium azide was not an effective antimicrobial agent. The subsequently used antibiotic-antimycotic mixture was initially effective in eliminating bacterial growth but its efficacy became exhausted as the testing period progressed. In the present pilot study, a predator bacterium Bdellovibrio bacteriovorus was shown to prey on the antibiotic resistant bacterium, suggesting its potential use in knee simulator wear testing. © 2013 Elsevier Ltd. All rights reserved.

Biant L.C.,Royal Infirmary | Gascoyne T.C.,Orthopaedic Innovation Center | Gascoyne T.C.,Concordia Joint Replacement Group | Bohm E.R.,Concordia Joint Replacement Group | Moran M.,Royal Infirmary
Proceedings of the Institution of Mechanical Engineers, Part H: Journal of Engineering in Medicine | Year: 2016

The purpose of this research was to determine the failure mechanisms and damage features of a TriboFit acetabular buffer implanted directly against a native, prepared acetabulum which was revised after 11months. Retrieval analyses were carried out via light microscopy, gravimetric wear assessment, and observer scoring of visible damage features on the buffer. The volume of material abraded from the backside of the buffer was estimated via three-dimensional reconstruction using a laser scanner. Scanning electron microscopy was used to confirm damage features and mechanisms. Severe abrasion to the backside of the buffer was the primary damage feature, while stippling damage was seen on the articular surface of the buffer. Material loss due to backside abrasion was approximated to be between 0.13360.085 g (gravimetric analyses) and 0.19360.053 g (three-dimensional reconstruction). Implantation of the TriboFit buffer against the patient's native acetabulum without a metal backing allowed for significant movement of the buffer against the bone, resulting in the abrasion seen on this implant. The stippling damage on the articular surface indicates an adhesive wear mechanism which exacerbates movement of the buffer against the acetabulum, thereby increasing backside abrasion. © Institution of Mechanical Engineers.

Gascoyne T.C.,Orthopaedic Innovation Center | Teeter M.G.,London Health Sciences Center | Guenther L.E.,Orthopaedic Innovation Center | Burnell C.D.,Concordia Joint Replacement Group | And 2 more authors.
Journal of Arthroplasty | Year: 2016

This study examines the damage and wear on the polyethylene (PE) inserts from 52 retrieved Genesis II total knee replacements to identify differences in tribological performance between matched pairs of cobalt-chromium (CoCr) and oxidized zirconium (OxZr) femoral components. Observer damage scoring and microcomputed tomography were used to quantify PE damage and wear, respectively. No significant differences were found between CoCr and OxZr groups in terms of PE insert damage, surface penetration, or wear. No severe damage such as cracking or delamination was noted on any of the 52 PE inserts. Observer damage scoring did not correlate with penetrative or volumetric PE wear. The more costly OxZr femoral component does not demonstrate clear tribological benefit over the standard CoCr component in the short term with this total knee replacement design. © 2016 Elsevier Inc.

Hawker G.,University of Toronto | Bohm E.R.,University of Manitoba | Conner-Spady B.,University of Calgary | De Coster C.,University of Calgary | And 7 more authors.
Arthritis and Rheumatology | Year: 2015

Objective As rates of total joint arthroplasty (TJA) for osteoarthritis (OA) rise, there is a need to ensure appropriate use. We undertook this study to develop criteria for appropriate use of TJA. Methods In prior work, we used qualitative methods to separately assess OA patients' and arthroplasty surgeons' perceptions regarding appropriateness of patient candidates for TJA. The current study reviewed the appropriateness themes that emerged from each group, and a series of statements were developed to reflect each unique theme or criterion. A group of arthroplasty surgeons then indicated their level of agreement with each statement using electronic voting. Where ≤70% agreed or disagreed, the criterion was discussed and revised, and revoting occurred. In standardized telephone interviews, OA patient focus group participants indicated their level of agreement with each revised criterion. Results Qualitative research in 58 OA patients and 14 arthroplasty surgeons identified 11 appropriateness criteria. Member-checking in 15 surgeons (including 5 who had participated in the qualitative study) resulted in agreement on 6 revised criteria. These included evidence of arthritis on joint examination, patient-reported symptoms negatively impacting quality of life, an adequate trial of appropriate nonsurgical treatment, realistic patient expectations of surgery, mental and physical readiness of patient for surgery, and patient-surgeon agreement that potential benefits exceed risks. Thirty-six of the original 58 OA patient focus group participants (62.1%) participated in the member-check interviews and endorsed all 6 criteria. Conclusion Patients and surgeons jointly endorsed 6 criteria for assessment of TJA appropriateness in OA patients. Prospective validation of these criteria (assessed preoperatively) as predictive of postoperative patient-reported outcomes is under way and will inform development of a surgeon-patient decision-support tool for assessment of TJA appropriateness. © 2015, American College of Rheumatology.

Anderson D.R.,Street Capital | Dunbar M.J.,Queen Elizabeth Health Science Center | Bohm E.R.,Concordia Joint Replacement Group | Belzile E.,University of Quebec | And 18 more authors.
Annals of Internal Medicine | Year: 2013

Background: The role of aspirin in thromboprophylaxis after total hip arthroplasty (THA) is controversial. Objective: To compare extended prophylaxis with aspirin and dalteparin for prevention of symptomatic venous thromboembolism (VTE) after THA. Design: Multicenter randomized, controlled trial with a noninferiority design based on a minimal clinically important difference of 2.0%. Randomization was electronically generated; patients were assigned to a treatment group through a Web-based program. Patients, physicians, study coordinators, health care team members, outcome adjudicators, and data analysts were blinded to interventions. (Current Controlled Trials: ISRCTN11902170) Setting: 12 tertiary care orthopedic referral centers in Canada. Patients: 778 patients who had elective unilateral THA between 2007 and 2010. Intervention: After an initial 10 days of dalteparin prophylaxis after elective THA, patients were randomly assigned to 28 days of dalteparin (n = 400) or aspirin (n = 386). Measurements: Symptomatic VTE confirmed by objective testing (primary efficacy outcome) and bleeding. Results: Five of 398 patients (1.3%) randomly assigned to dalteparin and 1 of 380 (0.3%) randomly assigned to aspirin had VTE (absolute difference, 1.0 percentage point [95% CI, -0.5 to 2.5 percentage points]). Aspirin was noninferior (P < 0.001) but not superior (P = 0.22) to dalteparin. Clinically significant bleeding occurred in 5 patients (1.3%) receiving dalteparin and 2 (0.5%) receiving aspirin. The absolute between-group difference in a composite of all VTE and clinically significant bleeding events was 1.7 percentage points (CI, -0.3 to 3.8 percentage points; P = 0.091) in favor of aspirin. Limitation: The study was halted prematurely because of difficulty with patient recruitment. Conclusion: Extended prophylaxis for 28 days with aspirin was noninferior to and as safe as dalteparin for the prevention of VTE after THA in patients who initially received dalteparin for 10 days. Given its low cost and greater convenience, aspirin may be considered a reasonable alternative for extended thromboprophylaxis after THA. Primary Funding Source: Canadian Institutes of Health Research. © 2013 American College of Physicians.

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