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Patrícia R Pinto,1,2 Teresa McIntyre,3 Vera Araújo-Soares,4 Patrício Costa,1,2,5 Ramón Ferrero,6 Armando Almeida1,2 1Life and Health Sciences Research Institute (ICVS), School of Medicine, University of Minho, Braga, 2ICVS/3B’s – PT Government Associate Laboratory, Braga/Guimarães, Portugal; 3Department of Psychology, Houston Baptist University, Houston, TX, USA; 4Institute of Health and Society, Faculty of Medical Sciences, Newcastle University, Newcastle upon Tyne, UK; 5Faculty of Psychology and Education Sciences, University of Porto, Porto, Portugal; 6Orthopedics Unit, Alto Ave Hospital Center, Guimarães, Portugal Background: Acute pain is an expected result after surgery. Nevertheless, when not appropriately controlled, acute pain has a very negative impact on individual clinical outcomes, impairing healing and recovery, and has clear consequences on health care system costs. Augmenting knowledge on predictors and potentially modifiable determinants of acute postsurgical pain can facilitate early identification of and intervention in patients at risk. However, only a few studies have examined and compared acute pain after total hip arthroplasty (THA) and total knee arthroplasty (TKA). The aim of this study was to compare THA and TKA in acute postsurgical pain intensity and its predictors.Methods: A consecutive sample of 124 patients with osteoarthritis (64 undergoing THA and 60 TKA) was assessed 24 hours before (T1) and 48 hours after (T2) surgery. Demographic, clinical, and psychological factors were assessed at T1, and acute postsurgical pain experience was examined at T2. Additionally, the same hierarchical regression analysis was performed separately for each arthroplasty type.Results: TKA patients reported higher levels of acute postsurgical pain compared with THA (t=8.490, p=0.004, d=0.527, 95% confidence interval, 0.196–0.878). In the final THA predictive model, presurgical pain was the only variable approaching significant results (t[57]=1.746, β=0.254, p=0.086). In the final TKA predictive model, optimism was the only predictor of pain (t[51]=–2.518, β=–0.339, p=0.015), with emotional representation (t[51]=1.895, β=0.254, p=0.064) presenting a trend toward significance.Conclusion: The current study is the first examining THA and TKA differences on acute postsurgical pain intensity and its predictors using a multivariate approach. Results from this study could prove useful for the design of distinct interventions targeting acute postsurgical pain management depending on whether the site of arthroplasty is the hip or the knee. Finally, the current results also support the argument that these two surgeries, at least with regard to acute pain, should be approached separately. Keywords: acute post-surgical pain, total knee arthroplasty, total hip arthroplasty, psychological factors, multivariate analyses, presurgical psychological intervention

Patrícia R Pinto,1–3 Teresa McIntyre,4,5 Ramón Ferrero,6 Vera Araújo-Soares,3,7 Armando Almeida1,2 1Life and Health Sciences Research Institute, School of Health Sciences, University of Minho, Braga, Portugal; 2Life and Health Sciences Research Institute/3Bs, PT Government Associate, Braga/Guimarães, Portugal; 3Health Psychology Group, Newcastle University, Newcastle, UK; 4Texas Institute for Measurement, Evaluation and Statistics, 5Department of Psychology, University of Houston, TX, USA; 6Alto Ave Hospital Center, Orthopedics Unit, Guimarães, Portugal; 7Institute of Health and Society, Faculty of Medical Sciences, Newcastle University, Newcastle, UK Abstract: This study compares the incidence, nature, and impact of persistent post-surgical pain after total knee arthroplasty (TKA) and total hip arthroplasty (THA) and investigates differences between these procedures, with the focus on potential presurgical and post-surgical issues that could be related to the distinct persistent post-surgical pain outcomes between these two groups. A consecutive sample of 92 patients was assessed prospectively 24 hours before, 48 hours, and 4–6 months after surgery. The data show that TKA patients had a higher likelihood of developing persistent post-surgical pain, of reporting higher pain levels, and of using more neuropathic descriptors when classifying their pain. In addition, TKA patients more often reported interference from pain on functional domains, including general activity, walking ability, and normal work. Demographic factors, like gender and age, along with presurgical clinical factors like disease onset, existence of medical comorbidities, and other pain problems, may have contributed to these differences, whereas baseline psychologic factors and functionality levels did not seem to exert an influence. Heightened acute post-surgical pain experience among TKA patients could also be related to distinct outcomes for persistent post-surgical pain. Future prospective studies should therefore collect TKA and THA samples wherein patients are homogeneous for demographic and presurgical clinical issues. Overall, these findings contribute to a small but growing body of literature documenting persistent post-surgical pain after major arthroplasty, conducted in different countries and across different health care settings. Keywords: total knee arthroplasty, total hip arthroplasty, persistent post-surgical pain, demographic factors, clinical factors, psychologic factors

In this paper we present two simulations designed with GeoGebra that illustrate dynamically a key concept in Vector Calculus: line integrals of vector fields, along with other associated mathematical properties and applications. Students are not required to know the GeoGebra environment: a user-friendly interface with buttons, functionalities and online help and exemplar problems allows immediate use of the simulations. The goal of the simulations is to enhance student insight, in the spirit of learning by experimentation, by analysing the dynamic representations provided by the simulations and by dragging objects and changing the parameters involved. The numerical results can be confirmed for special cases by standard undergraduate calculations.