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Clouthier A.L.,Queen's University | Clouthier A.L.,Human Mobility Research Center | Hetzler M.A.,Queen's University | Hetzler M.A.,Human Mobility Research Center | And 8 more authors.
Journal of Shoulder and Elbow Surgery | Year: 2013

Background: Despite the success of reverse shoulder arthroplasty (RSA) in treating patients with painful pseudoparalytic shoulders, instability is a common complication and currently the factors affecting stability are not well understood. The objective of this study was to investigate a number of factors as well as the interactions between factors to determine how they affect the stability of the prosthesis. These factors included: active arm posture (abduction and abduction plane angles), loading direction, glenosphere diameter and eccentricity, and humeral socket constraint. Methods: Force required to dislocate the joint, determined using a biomechanical shoulder simulator, was used as a measure of stability. A factorial design experiment was implemented to examine the factors and interactions. Results: Actively increasing the abduction angle by 15° leads to a 30% increase in stability and use of an inferior-offset rather than a centered glenosphere improved stability by 17%. Use of a more constrained humeral socket also increased stability; but the effect was dependent on loading direction, with a 88% improvement for superior loading, 66% for posterior, 36% for anterior, and no change for inferior loading. Abduction plane angle and glenosphere diameter had no effect on stability. Conclusion: Increased glenohumeral abduction and the use of an inferior-offset glenosphere were found to increase the stability of RSA. Additionally, use of a more constrained humeral socket increased stability for anterior, posterior, and superior loading. These identified factor effects have the potential to decrease the risk of dislocation following RSA. © 2013 Journal of Shoulder and Elbow Surgery Board of Trustees.


Cunic D.,Queen's University | Lacombe S.,Queen's University | Mohajer K.,Queen's University | Grant H.,Human Mobility Research Center | And 2 more authors.
Canadian Journal of Surgery | Year: 2014

Background: Knee and hip arthroplasty constitutes a large percentage of hospital elective surgical procedures. The Blaylock Risk Assessment Screening Score (BRASS) was designed to identify patients in need of discharge planning. The purpose of this study was to evaluate whether the BRASS was associated with length of stay (LOS) in hospital following elective arthroplasty.Methods: We retrospectively reviewed the charts of individuals undergoing primary elective arthroplasty for knee or hip osteoarthritis who had a documented BRASS score.Results: In our study cohort of 241, both BRASS (p < 0.001) and replacement type (hip v. knee; p = 0.048) were predictive of LOS. Higher BRASS was associated with older patients (p < 0.001), higher American Society of Anesthesiologists score (p < 0.001) and longer LOS (p < 0.001). We found a specificity of 83% for a BRASS greater than 8 and a hospital stay longer than 5 days and a specificity of 92% for a BRASS greater than 10.Conclusion: The BRASS represents a novel and significant predictor of LOS following elective arthroplasty. Patients with higher BRASS are more likely to stay in hospital 5 days or more and should receive pre-emptive social work consultations to facilitate timely discharge planning and hospital resources. © 2014 Association médicale canadienne.

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