Class of 2017 Abstract / Objectives: The first aim is to assess efficacy of aspirin versus enoxaparin in preventing a venous thromboembolism (VTE) after a total knee arthroplasty (TKA) or total hip arthroplasty (THA) within 30 days after discharge. The second aim is to assess the safety of aspirin versus enoxaparin in preventing major bleeding events after a TKA or THA within 30 days after discharge. Methods: This study was a retrospective cohort study with data obtained from an online Veterans Affairs (VA) hospital database. For analysis, the primary outcome was assessed with a Chi-Square test, and the secondary outcome was reported with descriptive statistics.Results: Results: Demographics for 374 patients (TKA, n = 275; THA, n = 99): 90% male, average age of 65, average body mass index (BMI) of 32, 26% smokers, 72% had a history of hypertension, and 60% had a history of dyslipidemia. VTE events 30 days post-operatively: enoxaparin (n = 2), enoxaparin/aspirin (n = 1), and aspirin (n = 2) (P-value = 0.78). Safety events (major bleeding events): enoxaparin (n = 42), enoxaparin/aspirin (n = 7), and aspirin (n = 4). Conclusions: There was no significant difference between the treatment groups for VTE rate 30 days post- operation. The enoxaparin treatment group had the greatest number of safety events compared to the other groups.

Class of 2013 Abstract / Specific Aims:  To determine the efficacy of apixaban when compared to LMWH (enoxaparin) when used as thromboprophylaxis for patients undergoing total hip arthroplasty (THA), total knee arthroplasty (TKA), and medically ill patients  To determine the safety of apixaban when compared to LMWH (enoxaparin) when used as thromboprophylaxis for patients undergoing total hip arthroplasty (THA), total knee arthroplasty (TKA), and medically ill patients Methods: A systematic search of the literature for randomized controlled trials of apixaban thromboprophylaxis therapy versus enoxaparin was conducted using three databases: PubMed, EMBASE, and the Cochrane library. Data from five studies with 12,938 total patients were analyzed using Bayesian random effects meta-analysis. To evaluate efficacy, a composite of venous thromboembolism and death during follow-up was measured. To evaluate safety, major and total bleeding events were considered. Main Results: The odds ratio (OR) for the composite outcome of thromboembolism/death was 0.66 (95% CI: 0.33 to 1.29) for apixaban compared to enoxaparin, while there was a similar risk of major bleeding (OR=1.03, 95%CI: 0.36 to 3.73) and total bleeding (OR=0.92, 95%CI: 0.64 to 1.20). Conclusion: These results suggest a lack of clear superiority of apixaban relative to enoxaparin. Apixaban is an oral alternative with similar efficacy and safety to existing anticoagulant therapies.

<p><strong>Background: </strong>Total joint arthroplasty (TJA) is considered the treatment of choice to alleviate pain and improve function of patients with osteoarthritis. However,recent evidence suggests that a significant proportion of patients continue to report pain, or worsening of their symptoms well after their joint replacement. We call this chronic pain “<em>phantom joint pain</em>” as it persists despite the fact hat the affected joint has been replaced.</p> <p>Chronic pain of neuropathic origin may be a consequence of surgery or in patients with osteoarthritis (OA); there may be a combination of nociceptive and neuropathic pain (NP) mechanisms. As there are no definitive physiological indicators for NP or gold standards for diagnosis, Guidelines on Neuropathic Pain Assessment advocate the use of screening tools to evaluate the patient’s pain experiences and potentially characterize various pain features.</p> <p>Despite suggestions that phantom joint pain post TJA is a common problem there is limited information about its prevalence among Canadians. To date there are no studies that have characterized neuropathic vs. non- neuropathic chronic pain features in a TJA population.</p> <p><strong>Purpose: </strong>The purpose of this work was to determine the<em> </em>prevalence of chronic pain following total hip (THA) or knee (TKA) arthroplasty, and to identify the proportion of the cohort with chronic pain whose symptoms suggested the pain was of neuropathic origin. In addition we evaluated the ability of the NP Subscale of the McGill pain questionnaire [NP-MPQ (SF-2)] to identify individuals with NP vs. Non NP in the TJA population.</p> <p><strong>Methods:</strong> A retrospective cohort study (2-4 years post joint replacement) of 148 participants with primary unilateral TJAidentified from a large joint arthroplasty database (n=1143). Chronic pain was defined as post surgical pain reported 6-12 months following surgery to be 3 or higher (out of 5) on the Oxford Hip/Knee Scores, and that pain was the same or worse than reported preoperatively. A postal survey was used to administer the NP-MPQ (SF-2)and the Self-Administered Leeds Assessment of Neuropathic Signs and Symptoms (S–LANSS) (1.5-3.5 years post TJA). S-LANSS was the “non reference standard” for classification of neuropathic pain. Human research ethics approvals from Sunnybrook Health Sciences Centre and McMaster University/Hamilton Health Sciences were obtained prior to the study.</p> <p><strong>Results</strong>: The response rate to the postal survey to identify those with chronic pain of neuropathic origin was 53%. Thirteen percent of individuals experienced chronic pain; among individuals with chronic pain, neuropathic subtype was found in 28% (S-LANSS ≥ 12) - 43% [NP-MPQ (SF-2) ≥ 0.91]. Receiver Operating Characteristic (ROC) analysis for NP-MPQ (SF-2) yielded an area under the curve of 0.89 (95% CI: 0.82, 0.97). A cut off score of 0.91 NP-MPQ (SF-2),<strong> </strong>maximized sensitivity (89.5%) and specificity (75.0%). Our results revealed moderate correlation (r=0.56; 95% CI: 0.40, 0.68) between the S-LANSS and NP-MPQ (SF-2)scores in patients with NP post TJA.</p> <p><strong>Conclusion: </strong>Based on our results, a considerable percentage of individuals (13%) experience chronic pain following TKA and THA. Moreover, among individuals with chronic pain symptoms, a significant proportion (28-43%) of those experience pain that appears to have a neuropathic component, even 1.5 to 3.5 years following surgery.Overall prevalence of NP in TJA was 3.3 to 4.5%. The NP-MPQ (SF-2)subscale demonstrated “good” discriminatory ability, thus it might be useful in identifying patients with NP following TJA. Moderate association exists between the scales and this could affect prevalence rates in studies; or diagnosis of NP of individual patients based on the criterion used.</p> / Master of Science (MSc)