Background: Total knee arthroplasty (TKA) is the treatment of choice for end-stage knee osteoarthritis. Growth in the number of procedures performed annually in the United States is expected to increase steadily. Post-operative rehabilitation settings vary and include both institutional and community based physical therapy (PT) services. Despite access to PT, deficits in gait often persist for months and even years after surgery. Slow gait speed, asymmetrical walking patterns, and prolonged time in double-limb support following the TKA often lead to the need for an assistive device for walking and prolong the rehabilitation phase. Purpose: The purpose of this study is to analyze early gait during inpatient rehabilitation to quantify both the improvements made and deficits that remain in important gait variables. This study identifies predictor variables that contribute to the variance in discharge ambulation device use and IRF length of stay. Subjects: A convenience sample of 230 patients discharged to an IRF following a TKA (160 following a single TKA and 70 following a bilateral procedure) was used for this analysis. Method: Paired t-tests were used to compare temporal and spatial gait variables from the initial gait assessment compared to the discharge gait assessment in patients following single TKA to determine remaining deficits. Right vs left comparisons were made for patients following a bilateral procedure. A binary logistic regression was used to identify predictors associated with the need for a two-handed ambulation device at discharge. A multiple linear regression developed a model to assess predictors of the inpatient rehabilitation length of stay. Finally, a self-assessment to evaluate patient confidence with walking (mGES scale) was correlated to actual gait speed performed on the gait analysis in a sample of patients from our study population. Findings: Deficits in step length, step time and percent of single limb support remained in the involved limb compared to uninvolved limb at discharge from inpatient rehabilitation following single TKA; no limb differences between the right and left side were noted in patients after bilateral TKA. The discharge gait speed of 54.6 cm/sec for single TKA patients and discharge speed of 61.5 cm/sec for bilateral TKA patients is within the classification of limited community ambulators and making them appropriate for a home discharge. But despite improvement from admission to discharge, the gait speed for both groups in our study remain below the gait speed identified by prior studies 3-months following TKA surgery where speed reached 135 cm/sec. The need for a two-handed ambulation device, such as bilateral canes or a walker, was associated with slow walking speed and prior use of a device before surgery. A longer rehabilitation length of stay was associated with slower initial gait speed, lower motor FIM scores and reduced knee extension at admission. The mGES patient self-report conducted at the time of the discharge gait assessment showed a moderate correlation to the discharge gait speed; however, the pairing of the admission mGES with the admission gait speed was not significantly correlated.

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Knee osteoarthritis is a growing problem due to increasing risk factors such as age and obesity. It is a common task for a radiologist to grade osteoarthritis in three compartments (medial tibiofemoral (MTF), lateral tibiofemoral (LTF) and patellofemoral (PF)) in a knee from different image views of X-ray images, to decide if osteoarthritis is the cause of pain for the patient. Reasons for automating this process are to decrease subjectivity, time for diagnosis and reduce workload for radiologists. The aim with this project was to grade osteoarthritis using machine learning by training convolutional neural networks on around 5000 double annotated examinations by radiologists and one orthopaedic surgeon at Nyköping Hospital. Different methods were evaluated and the models were then optimised with hyperparameter tuning. The aim with the project is to contribute to a future software that could be tested at Nyköping Hospital. The project found that using transfer learning with DenseNet for MTF and PF, and using a MTF model as transfer learning model for the LTF model was the best performing transfer learning networks to use. Also, cropping the images around the region of interest for MTF and LTF improved the models. The best method to make predictions from the model outputs appeared to be to train a model on a merged set of training- and validation data for making predictions. Comparisons of final models with the radiologist initial annotations showed that the MTF and LTF models give fewer misclassifications of more than one grade, if compared to the disagreements of more than one grade by the two radiologists. While for the PF model the radiologists still have an advantage and more data is probably needed for both the PF model and the LTF model since grade 0 is very overrepresented for those grades.

With an increasing prevalence of osteoarthritis, total knee (TKA) and hip (THA) arthroplasty are the second-and third-most common surgeries in Canada. Although these procedures improve pain and function for a majority of patients, some patients report persistent postoperative pain. Opioids are conventionally used for these patients even though they are associated with addiction, falls, overdose, and death. Recently, many strategies have been proposed to decrease reliance on opioids after TKA and THA, including opioid-free and opioid-reduced multimodal protocols for pain management. Our findings demonstrate that Canadian patients’ receptivity to opioid-free or reduced postoperative protocols is associated with their perception of the efficacy and safety of opioids compared to non-opioid alternatives, and current opioid use. More patients are open to opioid-reduced postoperative care as they perceive that pain will be intolerable without opioids. This overlaps with many Canadian surgeons’ perception that opioids cannot be completely eliminated from postoperative pain management regimens and that patients expect an intolerable level of pain after surgery, warranting opioid use. This highlights a need for enhanced patient education on the safety and efficacy of opioids and alternatives, while managing patients’ expectations of postoperative pain control. Most Canadian and Dutch surgeons reported that they prescribe opioids to nearly all of their patients postoperatively. However, our cross-sectional study indicates that 40% of Canadian patients would be open to receiving no opioids postoperatively. In contrast, Japanese surgeons believed that opioids are unnecessary for managing postoperative pain. Variations observed among orthopaedic surgeons in Canada, the Netherlands, and Japan can be attributed to differences at the surgeon-level (individual practices and beliefs), patient-level (patient characteristics and preferences), and system-level (regulatory frameworks and healthcare systems). Further research is required on surgeon-centered approaches to mitigating opioid use, focusing on education and guidelines/policies for opioid prescribing. / Thesis / Master of Science (MSc) / Opioid analgesics are routinely prescribed to manage pain after total knee and hip replacement surgery. However, opioids are not typically more effective than alternatives and are associated with addiction, overdose, and death. This thesis aims to understand the perceptions of patients and orthopaedic surgeons on opioid use after total knee and hip replacement surgery. The findings demonstrate that more patients are open to receiving opioid-reduced surgery compared to opioid-free surgery, with receptivity being associated with patients’ perceptions of opioid efficacy and safety and current opioid use, highlighting a need for improved patient education. Additionally, orthopaedic surgeons identified challenges and facilitators to postoperative opioid reduction in six key areas: opioid prescribing practices, patient factors, collaborative care, policies/guidelines, surgeon education and training, and personal perceptions/beliefs. Compared to Canadian and Dutch surgeons, Japanese surgeons heavily relied on non-opioid medications as they believed that opioids are unnecessary for managing postoperative pain.

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Magnetic resonance imaging (MRI) has become the most important modality for assessment of pathological changes in the knee cartilage. The assessment of the cartilage is usually made by a set of anatomical MRI images with different sequences. Newer techniques, that map various in MRI parameters, have been developed and allows changes in an earlier stage of the disease. One of these techniques is T2 mapping. The goal of this thesis was to compare this newer technique, T2 mapping, with the standard MRI assessment for assessment of articular cartilage on distal femur in the knee. The purpose was to assess the cartilage with these two different methods and analyze its outcomes. Eight subjects were included in this study and scanned with a 3.0 T or 1.5 T MRI machine. A specific MRI knee protocol was used for the standard MRI assessment, and a multi-echo sequence was used for the T2 mapping. The T2 map was created and analyzed in the program IntelliSpace Portal. Both the standard MRI assessment and the T2 map showed changes in the knee cartilage. The result showed either indication for damage cartilage or healthy cartilage. The standard assessment showed cartilage lesion in three subjects and no lesion in five subjects. The same outcomes were with the T2 mapping. However, not all results were equal. The T2 mapping also showed higher values in the trochlea area where no indications for changes were found in the standard assessment. This study showed similar results for both the standard assessment and the T2 map. Both methods could identify damage and is, therefore, useful for assessment of the knee cartilage. The outcomes of the different methods differ, and the assessment is therefore made in different ways. The T2 mapping can be analyzed both visual and quantitative. The outcomes were both a color map of the knee but also results in graphs and values. The standard assessment is only assessed from grayscale images. The best outcomes from the T2 mapping was when it only was changes within the cartilage and not when the cartilage lesion was adjacent to an underlying bone lesion. Based on what was examined in this work, the best result was when T2 mapping was used together with the anatomical images used in the standard assessment. The conclusion is that the standard assessment is necessary when it comes to make a damage assessment and perform damage marking as for Episurf. The T2 mapping is, however, an interesting method and will be more useful with more applications in the future. It is therefore exciting to keep an eye on the technology and its development. / Magnetisk resonanstomografi (MR) har blivit den viktigaste modaliteten vid bedömning av patologiska förändingar i knäbrosket. Bedömningen av brosket görs vanligtvis med hjälp av anatomiska MR bilder som är skannade med olika sekvenser för att få olika viktningar på bilderna. En nyare teknik, T2 mappning, som kartlägger olika MR prameterar, har utvecklats för att med hjälp av andra parametrar analysera knäbrosket. Den här tekniken har resulterat i att förändringar i brosket kan upptäckas vid ett tidigare stadie i sjukdomsförloppet. Målet med det här examensarbetet var att jämföra de olika teknikerna, T2 mappning och MR-standardbedömningen, för att bedöma ledbrosket på distala lårbenet i knäet. Syftet var att bedöma brosket utifrån dessa olika metoder samt att analysera och jämföra dess resultat. Åtta subjekt ingick i studien och skannades med en 3,0 T eller 1,5 T MR-maskin. Ett specifikt MR-knäprotokoll användes för att skanna sekvenserna som ingick i standard bedömningen och en multi-ekosekvens användes för T2 mappningen. T2-mappningen skapades och analyserades sedan i programmet IntelliSpace Portal. Både standard MR-bedömningen och T2-mappningen visade tydliga förändringar i brosket. Resultatet visade antingen indikationer på skadat eller friskt brosk. Standardbedömningen visade broskskador hos tre subjekt och inga broskskador hos fem subjekt. Samma resultat visades med T2-mappningen. Däremot skilde sig vissa resultat mellan T2 mappningen och standardbedömningen. Då denna studie visade liknande resultat för både standardbedömningen och T2-mappningen, är båda metoderna användbara för bedömning av knäbrosket. De olika metoderna har olika utfall vilket gör att bedömningen sker på olika sätt. I T2 mapping får man ut både en färgkarta över knät men också grafter och värden som kan användas. I standardbedömningen görs bedömningen bara utifrån olika gråskalebilder. T2 mappningen var mest användbar när det var tydliga förändingar i bara brosket och inte när skadan mest var i benet. Det bästa resultatet var däremot när T2 mappning användes tillsammans med standardbedömningen. Slutsatsen är att standardbedömningen är nödvändig när det kommer till att bedömma skador och göra en skademarkering så som för Episurf. T2 mapping är däremot en väldigt intressant teknik men är idag inte en vanlig teknik inom diagnostiken och saknar just nu något tydligt användningsområde. Däremot, finns det stor potential och kommer troligtvis bli vanligare och få fler användingsområden i framtiden.

Introduction: Lower extremity (LE) work-related musculoskeletal disorders (WMSDs) are known to occur with cumulative exposure to occupational and personal risks. The objective of this dissertation study was to find if creating a quantifiable risk detection model for the LE was feasible. The primary product of the literature review conducted for this study resulted in focusing the attention of the model development process onto creating the initial model of the LE for assessing knee disorder risk factors. Literature Review: LE occupational disorders affect numerous industries and thousands of people each year by affecting any one of the musculoskeletal systems deemed susceptible by the occupational and personal risk factors involved. Industries known to be affected tend to have labor intensive job descriptions. Some of the numerous industry examples include mining, manufacturing, firefighting, and carpet laying. Types of WMSDs noticed by the literature include bursitis, osteoarthritis, stress fractures, tissue inflammation, and nerve entrapment. In addition to the occupationally related disorders that may develop, occupationally related discomforts were also taken into consideration by this study. Generally, both the disorders and the discomforts can be traced to either a personal or occupational risk factor or both. Personal risk factors noted by the literature include a person's physical fitness and health history (such as past injuries). Meanwhile, occupational risks can be generalized to physical postures, activities, and even joint angles. Prevalence data over a three year interval (2003-2005) has found that LE WMSDs make up on average approximately 7.5% of all the WMSD cases reported to the US Occupational Safety and Health Administration (OSHA). When the literature is refined to the information pertaining to occupational knee disorders, the mean prevalence percentage of the same three year range is about 5%. Mean cost for knee injuries were found to be $18,495 (for the year between 2003 and 2004). Methodology: Developing a risk model for the knee meant using groups of subject matter experts for model development and task hazard analysis. Sample occupational risk data also needed to be gathered for each of a series of tasks so that the model could be validated. These sample data were collected from a sample aircraft assembly plant of a US aerospace manufacturer. Results: Based on the disorder and risk data found in the literature, a knee risk assessment model was developed to utilize observational, questionnaire, and direct measure data collection methods. The final version of this study's knee model has an inventory of 11 risk factors (8 occupational and 3 personal) each with varying degrees of risk exposure thresholds (e.g., high risk, moderate risk, or minimal risk). For the occupational risk assessment portion of the model, the results of task evaluations include both an occupational risk resultant score (risk score) and a task risk level (safe or hazardous). This set of results is also available for a cumulative (whole day) assessment. The personal risk assessment portion only produces a risk resultant score. Validation of the knee risk model reveals statistically (t (34) = 1.512, p = 0.156), that it is functioning as it should and can decide between hazardous and safe tasks. Additionally, the model is also capable of analyzing tasks as a series of cumulative daily events and providing an occupational and personal risk overview for individuals. Conclusion: While the model proved to be functional to the given sample site and hypothetical situations, further studies are needed outside of the aerospace manufacturing environment to continue testing both the model's validity and applicability to other industrial environments. The iterative adjustments generated for the occupational risk portion of the model (to reduce false positives and negatives) will need additional studies that will further evaluate professional human judgment of knee risk against this model's results. Future investigations must also make subject matter experts aware of the minimal risk levels of this knee risk assessment model so that task observational results are equally comparable. Additional studies are moreover needed to assess the intimate nature between variable interactions; especially multiple model defined minimal risks within a single task.

Articular cartilage is a specialized connective soft tissue that resides onthe ends of long-bones, transfers the load smoothly between the bones in diarthrodialjoints by providing almost frictionless, wear resistant sliding surfacesduring joint articulation. Focal chondral or osteochondral defects in articularcartilage are common and show limited capacity for biological repair. Furthermore,changes in the bio-mechanical forces at the defect site may makethe tissue more susceptible to continued degeneration. Alternatively, the contouredfocal resurfacing metal implant can be used to treat such full thicknesscartilage defects. Physiological and biomechanical studies on animal modelswith metal implant have shown good clinical outcomes. However, the mechanicalbehavior of cartilage surrounding the implant is not clearly known withrespect to the joint function after treating such defects with metal implantsand also to improve the implant design. We developed a simple 3-dimensionalfinite element model by approximating one of the condyles of the sheep kneejoint. Parametric study was conducted in the simulations to verify differentprofiles for the implant, positioning of the implant with respect to cartilagesurface, defect size and to show the mechanical sealing effect due to the wedgeshape of the implant. We found the maximal deformations, contact pressuresand stresses which constitute the mechanical behavior of cartilages. We alsoconfirmed that using a metal implant to fill the full thickness chondral defectsis more beneficial than to leave the defect untreated from mechanical point ofview. The implant should be positioned slightly sunk into the cartilage basedon the defect size, in order to avoid damage to the opposing surface. The largerthe defect size, the closer the implant should be to the flush. We also simulatedthe time dependent behavior of the cartilages. In all the simulations, a staticaxial loading was considered. The wedge shape of the implant provided themechanical sealing of the cartilage surrounding the implant. The determineddeformations in the cartilages immediately surrounding the implant are instrumentalin predicting the sticking-up of the implant into the joint cavity whichmay damage opposing soft tissues. / <p>QC 20101125</p>